2010-12-07 08:29:22 +08:00
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/*
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* Xen leaves the responsibility for maintaining p2m mappings to the
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* guests themselves, but it must also access and update the p2m array
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* during suspend/resume when all the pages are reallocated.
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*
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* The p2m table is logically a flat array, but we implement it as a
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* three-level tree to allow the address space to be sparse.
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*
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* Xen
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* |
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* p2m_top p2m_top_mfn
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* / \ / \
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* p2m_mid p2m_mid p2m_mid_mfn p2m_mid_mfn
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* / \ / \ / /
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* p2m p2m p2m p2m p2m p2m p2m ...
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*
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* The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
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*
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* The p2m_top and p2m_top_mfn levels are limited to 1 page, so the
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* maximum representable pseudo-physical address space is:
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* P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
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*
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* P2M_PER_PAGE depends on the architecture, as a mfn is always
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* unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
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* 512 and 1024 entries respectively.
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xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
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p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
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*
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* In short, these structures contain the Machine Frame Number (MFN) of the PFN.
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*
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* However not all entries are filled with MFNs. Specifically for all other
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* leaf entries, or for the top root, or middle one, for which there is a void
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* entry, we assume it is "missing". So (for example)
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* pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
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*
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* We also have the possibility of setting 1-1 mappings on certain regions, so
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* that:
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* pfn_to_mfn(0xc0000)=0xc0000
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*
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* The benefit of this is, that we can assume for non-RAM regions (think
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* PCI BARs, or ACPI spaces), we can create mappings easily b/c we
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* get the PFN value to match the MFN.
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*
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* For this to work efficiently we have one new page p2m_identity and
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* allocate (via reserved_brk) any other pages we need to cover the sides
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* (1GB or 4MB boundary violations). All entries in p2m_identity are set to
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* INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
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* no other fancy value).
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*
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* On lookup we spot that the entry points to p2m_identity and return the
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* identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
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* If the entry points to an allocated page, we just proceed as before and
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* return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
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* appropriate functions (pfn_to_mfn).
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*
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* The reason for having the IDENTITY_FRAME_BIT instead of just returning the
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* PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
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* non-identity pfn. To protect ourselves against we elect to set (and get) the
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* IDENTITY_FRAME_BIT on all identity mapped PFNs.
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*
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* This simplistic diagram is used to explain the more subtle piece of code.
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* There is also a digram of the P2M at the end that can help.
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* Imagine your E820 looking as so:
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*
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* 1GB 2GB
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* /-------------------+---------\/----\ /----------\ /---+-----\
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* | System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
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* \-------------------+---------/\----/ \----------/ \---+-----/
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* ^- 1029MB ^- 2001MB
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*
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* [1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100),
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* 2048MB = 524288 (0x80000)]
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*
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* And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
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* is actually not present (would have to kick the balloon driver to put it in).
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*
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* When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
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* Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
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* of the PFN and the end PFN (263424 and 512256 respectively). The first step
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* is to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
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* covers 512^2 of page estate (1GB) and in case the start or end PFN is not
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* aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn
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* to end pfn. We reserve_brk top leaf pages if they are missing (means they
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* point to p2m_mid_missing).
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*
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* With the E820 example above, 263424 is not 1GB aligned so we allocate a
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* reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
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* Each entry in the allocate page is "missing" (points to p2m_missing).
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*
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* Next stage is to determine if we need to do a more granular boundary check
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* on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
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* We check if the start pfn and end pfn violate that boundary check, and if
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* so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
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* granularity of setting which PFNs are missing and which ones are identity.
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* In our example 263424 and 512256 both fail the check so we reserve_brk two
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* pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing"
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* values) and assign them to p2m[1][2] and p2m[1][488] respectively.
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*
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* At this point we would at minimum reserve_brk one page, but could be up to
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* three. Each call to set_phys_range_identity has at maximum a three page
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* cost. If we were to query the P2M at this stage, all those entries from
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* start PFN through end PFN (so 1029MB -> 2001MB) would return
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* INVALID_P2M_ENTRY ("missing").
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*
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* The next step is to walk from the start pfn to the end pfn setting
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* the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity.
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* If we find that the middle leaf is pointing to p2m_missing we can swap it
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* over to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this
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* point we do not need to worry about boundary aligment (so no need to
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* reserve_brk a middle page, figure out which PFNs are "missing" and which
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* ones are identity), as that has been done earlier. If we find that the
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* middle leaf is not occupied by p2m_identity or p2m_missing, we dereference
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* that page (which covers 512 PFNs) and set the appropriate PFN with
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* IDENTITY_FRAME_BIT. In our example 263424 and 512256 end up there, and we
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* set from p2m[1][2][256->511] and p2m[1][488][0->256] with
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* IDENTITY_FRAME_BIT set.
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*
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* All other regions that are void (or not filled) either point to p2m_missing
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* (considered missing) or have the default value of INVALID_P2M_ENTRY (also
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* considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
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* contain the INVALID_P2M_ENTRY value and are considered "missing."
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*
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* This is what the p2m ends up looking (for the E820 above) with this
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* fabulous drawing:
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*
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* p2m /--------------\
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* /-----\ | &mfn_list[0],| /-----------------\
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* | 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
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* |-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
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* | 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
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* |-----| \ | [p2m_identity]+\\ | .... |
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* | 2 |--\ \-------------------->| ... | \\ \----------------/
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* |-----| \ \---------------/ \\
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* | 3 |\ \ \\ p2m_identity
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* |-----| \ \-------------------->/---------------\ /-----------------\
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* | .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
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* \-----/ / | [p2m_identity]+-->| ..., ~0 |
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* / /---------------\ | .... | \-----------------/
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* / | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
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* / | IDENTITY[@256]|<----/ \---------------/
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* / | ~0, ~0, .... |
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* | \---------------/
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* |
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* p2m_missing p2m_missing
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* /------------------\ /------------\
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* | [p2m_mid_missing]+---->| ~0, ~0, ~0 |
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* | [p2m_mid_missing]+---->| ..., ~0 |
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* \------------------/ \------------/
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*
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* where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
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2010-12-07 08:29:22 +08:00
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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2010-12-15 21:19:33 +08:00
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#include <linux/list.h>
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#include <linux/hash.h>
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2010-12-13 22:42:30 +08:00
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#include <linux/sched.h>
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2010-12-22 21:57:30 +08:00
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#include <linux/seq_file.h>
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2010-12-07 08:29:22 +08:00
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#include <asm/cache.h>
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#include <asm/setup.h>
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#include <asm/xen/page.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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#include "xen-ops.h"
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2010-12-15 21:19:33 +08:00
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static void __init m2p_override_init(void);
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2010-12-07 08:29:22 +08:00
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unsigned long xen_max_p2m_pfn __read_mostly;
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#define P2M_PER_PAGE (PAGE_SIZE / sizeof(unsigned long))
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#define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *))
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#define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **))
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#define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
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/* Placeholders for holes in the address space */
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static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
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static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
|
|
|
|
|
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
|
|
|
|
|
|
2010-12-07 08:29:22 +08:00
|
|
|
RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
|
|
|
|
|
RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
|
|
|
|
|
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
/* We might hit two boundary violations at the start and end, at max each
|
|
|
|
|
* boundary violation will require three middle nodes. */
|
|
|
|
|
RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
|
|
|
|
|
|
2010-12-07 08:29:22 +08:00
|
|
|
static inline unsigned p2m_top_index(unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
BUG_ON(pfn >= MAX_P2M_PFN);
|
|
|
|
|
return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static inline unsigned p2m_mid_index(unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static inline unsigned p2m_index(unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
return pfn % P2M_PER_PAGE;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void p2m_top_init(unsigned long ***top)
|
|
|
|
|
{
|
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < P2M_TOP_PER_PAGE; i++)
|
|
|
|
|
top[i] = p2m_mid_missing;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void p2m_top_mfn_init(unsigned long *top)
|
|
|
|
|
{
|
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < P2M_TOP_PER_PAGE; i++)
|
|
|
|
|
top[i] = virt_to_mfn(p2m_mid_missing_mfn);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void p2m_top_mfn_p_init(unsigned long **top)
|
|
|
|
|
{
|
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < P2M_TOP_PER_PAGE; i++)
|
|
|
|
|
top[i] = p2m_mid_missing_mfn;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void p2m_mid_init(unsigned long **mid)
|
|
|
|
|
{
|
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < P2M_MID_PER_PAGE; i++)
|
|
|
|
|
mid[i] = p2m_missing;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void p2m_mid_mfn_init(unsigned long *mid)
|
|
|
|
|
{
|
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < P2M_MID_PER_PAGE; i++)
|
|
|
|
|
mid[i] = virt_to_mfn(p2m_missing);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void p2m_init(unsigned long *p2m)
|
|
|
|
|
{
|
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < P2M_MID_PER_PAGE; i++)
|
|
|
|
|
p2m[i] = INVALID_P2M_ENTRY;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Build the parallel p2m_top_mfn and p2m_mid_mfn structures
|
|
|
|
|
*
|
|
|
|
|
* This is called both at boot time, and after resuming from suspend:
|
|
|
|
|
* - At boot time we're called very early, and must use extend_brk()
|
|
|
|
|
* to allocate memory.
|
|
|
|
|
*
|
|
|
|
|
* - After resume we're called from within stop_machine, but the mfn
|
|
|
|
|
* tree should alreay be completely allocated.
|
|
|
|
|
*/
|
2011-02-12 00:37:41 +08:00
|
|
|
void __ref xen_build_mfn_list_list(void)
|
2010-12-07 08:29:22 +08:00
|
|
|
{
|
|
|
|
|
unsigned long pfn;
|
|
|
|
|
|
|
|
|
|
/* Pre-initialize p2m_top_mfn to be completely missing */
|
|
|
|
|
if (p2m_top_mfn == NULL) {
|
|
|
|
|
p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_mid_mfn_init(p2m_mid_missing_mfn);
|
|
|
|
|
|
|
|
|
|
p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_top_mfn_p_init(p2m_top_mfn_p);
|
|
|
|
|
|
|
|
|
|
p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_top_mfn_init(p2m_top_mfn);
|
|
|
|
|
} else {
|
|
|
|
|
/* Reinitialise, mfn's all change after migration */
|
|
|
|
|
p2m_mid_mfn_init(p2m_mid_missing_mfn);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
|
|
|
|
|
unsigned topidx = p2m_top_index(pfn);
|
|
|
|
|
unsigned mididx = p2m_mid_index(pfn);
|
|
|
|
|
unsigned long **mid;
|
|
|
|
|
unsigned long *mid_mfn_p;
|
|
|
|
|
|
|
|
|
|
mid = p2m_top[topidx];
|
|
|
|
|
mid_mfn_p = p2m_top_mfn_p[topidx];
|
|
|
|
|
|
|
|
|
|
/* Don't bother allocating any mfn mid levels if
|
|
|
|
|
* they're just missing, just update the stored mfn,
|
|
|
|
|
* since all could have changed over a migrate.
|
|
|
|
|
*/
|
|
|
|
|
if (mid == p2m_mid_missing) {
|
|
|
|
|
BUG_ON(mididx);
|
|
|
|
|
BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
|
|
|
|
|
p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
|
|
|
|
|
pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
|
|
|
|
|
continue;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (mid_mfn_p == p2m_mid_missing_mfn) {
|
|
|
|
|
/*
|
|
|
|
|
* XXX boot-time only! We should never find
|
|
|
|
|
* missing parts of the mfn tree after
|
|
|
|
|
* runtime. extend_brk() will BUG if we call
|
|
|
|
|
* it too late.
|
|
|
|
|
*/
|
|
|
|
|
mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_mid_mfn_init(mid_mfn_p);
|
|
|
|
|
|
|
|
|
|
p2m_top_mfn_p[topidx] = mid_mfn_p;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
|
|
|
|
|
mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
void xen_setup_mfn_list_list(void)
|
|
|
|
|
{
|
|
|
|
|
BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
|
|
|
|
|
|
|
|
|
|
HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
|
|
|
|
|
virt_to_mfn(p2m_top_mfn);
|
|
|
|
|
HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* Set up p2m_top to point to the domain-builder provided p2m pages */
|
|
|
|
|
void __init xen_build_dynamic_phys_to_machine(void)
|
|
|
|
|
{
|
|
|
|
|
unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
|
|
|
|
|
unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
|
|
|
|
|
unsigned long pfn;
|
|
|
|
|
|
|
|
|
|
xen_max_p2m_pfn = max_pfn;
|
|
|
|
|
|
|
|
|
|
p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_init(p2m_missing);
|
|
|
|
|
|
|
|
|
|
p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_mid_init(p2m_mid_missing);
|
|
|
|
|
|
|
|
|
|
p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_top_init(p2m_top);
|
|
|
|
|
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_init(p2m_identity);
|
|
|
|
|
|
2010-12-07 08:29:22 +08:00
|
|
|
/*
|
|
|
|
|
* The domain builder gives us a pre-constructed p2m array in
|
|
|
|
|
* mfn_list for all the pages initially given to us, so we just
|
|
|
|
|
* need to graft that into our tree structure.
|
|
|
|
|
*/
|
|
|
|
|
for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
|
|
|
|
|
unsigned topidx = p2m_top_index(pfn);
|
|
|
|
|
unsigned mididx = p2m_mid_index(pfn);
|
|
|
|
|
|
|
|
|
|
if (p2m_top[topidx] == p2m_mid_missing) {
|
|
|
|
|
unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
p2m_mid_init(mid);
|
|
|
|
|
|
|
|
|
|
p2m_top[topidx] = mid;
|
|
|
|
|
}
|
|
|
|
|
|
xen: p2m: correctly initialize partial p2m leaf
After changing the p2m mapping to a tree by
commit 58e05027b530ff081ecea68e38de8d59db8f87e0
xen: convert p2m to a 3 level tree
and trying to boot a DomU with 615MB of memory, the following crash was
observed in the dump:
kernel direct mapping tables up to 26f00000 @ 1ec4000-1fff000
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<c0107397>] xen_set_pte+0x27/0x60
*pdpt = 0000000000000000 *pde = 0000000000000000
Adding further debug statements showed that when trying to set up
pfn=0x26700 the returned mapping was invalid.
pfn=0x266ff calling set_pte(0xc1fe77f8, 0x6b3003)
pfn=0x26700 calling set_pte(0xc1fe7800, 0x3)
Although the last_pfn obtained from the startup info is 0x26700, which
should in turn not be hit, the additional 8MB which are added as extra
memory normally seem to be ok. This lead to looking into the initial
p2m tree construction, which uses the smaller value and assuming that
there is other code handling the extra memory.
When the p2m tree is set up, the leaves are directly pointed to the
array which the domain builder set up. But if the mapping is not on a
boundary that fits into one p2m page, this will result in the last leaf
being only partially valid. And as the invalid entries are not
initialized in that case, things go badly wrong.
I am trying to fix that by checking whether the current leaf is a
complete map and if not, allocate a completely new page and copy only
the valid pointers there. This may not be the most efficient or elegant
solution, but at least it seems to allow me booting DomUs with memory
assignments all over the range.
BugLink: http://bugs.launchpad.net/bugs/686692
[v2: Redid a bit of commit wording and fixed a compile warning]
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-20 22:38:23 +08:00
|
|
|
/*
|
|
|
|
|
* As long as the mfn_list has enough entries to completely
|
|
|
|
|
* fill a p2m page, pointing into the array is ok. But if
|
|
|
|
|
* not the entries beyond the last pfn will be undefined.
|
|
|
|
|
*/
|
|
|
|
|
if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
|
|
|
|
|
unsigned long p2midx;
|
2011-01-27 23:03:14 +08:00
|
|
|
|
|
|
|
|
p2midx = max_pfn % P2M_PER_PAGE;
|
|
|
|
|
for ( ; p2midx < P2M_PER_PAGE; p2midx++)
|
|
|
|
|
mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
|
|
|
|
|
}
|
|
|
|
|
p2m_top[topidx][mididx] = &mfn_list[pfn];
|
2010-12-07 08:29:22 +08:00
|
|
|
}
|
2010-12-15 21:19:33 +08:00
|
|
|
|
|
|
|
|
m2p_override_init();
|
2010-12-07 08:29:22 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
unsigned long get_phys_to_machine(unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
unsigned topidx, mididx, idx;
|
|
|
|
|
|
|
|
|
|
if (unlikely(pfn >= MAX_P2M_PFN))
|
|
|
|
|
return INVALID_P2M_ENTRY;
|
|
|
|
|
|
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
|
|
|
mididx = p2m_mid_index(pfn);
|
|
|
|
|
idx = p2m_index(pfn);
|
|
|
|
|
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
/*
|
|
|
|
|
* The INVALID_P2M_ENTRY is filled in both p2m_*identity
|
|
|
|
|
* and in p2m_*missing, so returning the INVALID_P2M_ENTRY
|
|
|
|
|
* would be wrong.
|
|
|
|
|
*/
|
|
|
|
|
if (p2m_top[topidx][mididx] == p2m_identity)
|
|
|
|
|
return IDENTITY_FRAME(pfn);
|
|
|
|
|
|
2010-12-07 08:29:22 +08:00
|
|
|
return p2m_top[topidx][mididx][idx];
|
|
|
|
|
}
|
|
|
|
|
EXPORT_SYMBOL_GPL(get_phys_to_machine);
|
|
|
|
|
|
|
|
|
|
static void *alloc_p2m_page(void)
|
|
|
|
|
{
|
|
|
|
|
return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static void free_p2m_page(void *p)
|
|
|
|
|
{
|
|
|
|
|
free_page((unsigned long)p);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Fully allocate the p2m structure for a given pfn. We need to check
|
|
|
|
|
* that both the top and mid levels are allocated, and make sure the
|
|
|
|
|
* parallel mfn tree is kept in sync. We may race with other cpus, so
|
|
|
|
|
* the new pages are installed with cmpxchg; if we lose the race then
|
|
|
|
|
* simply free the page we allocated and use the one that's there.
|
|
|
|
|
*/
|
|
|
|
|
static bool alloc_p2m(unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
unsigned topidx, mididx;
|
|
|
|
|
unsigned long ***top_p, **mid;
|
|
|
|
|
unsigned long *top_mfn_p, *mid_mfn;
|
|
|
|
|
|
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
|
|
|
mididx = p2m_mid_index(pfn);
|
|
|
|
|
|
|
|
|
|
top_p = &p2m_top[topidx];
|
|
|
|
|
mid = *top_p;
|
|
|
|
|
|
|
|
|
|
if (mid == p2m_mid_missing) {
|
|
|
|
|
/* Mid level is missing, allocate a new one */
|
|
|
|
|
mid = alloc_p2m_page();
|
|
|
|
|
if (!mid)
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
p2m_mid_init(mid);
|
|
|
|
|
|
|
|
|
|
if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
|
|
|
|
|
free_p2m_page(mid);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
top_mfn_p = &p2m_top_mfn[topidx];
|
|
|
|
|
mid_mfn = p2m_top_mfn_p[topidx];
|
|
|
|
|
|
|
|
|
|
BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
|
|
|
|
|
|
|
|
|
|
if (mid_mfn == p2m_mid_missing_mfn) {
|
|
|
|
|
/* Separately check the mid mfn level */
|
|
|
|
|
unsigned long missing_mfn;
|
|
|
|
|
unsigned long mid_mfn_mfn;
|
|
|
|
|
|
|
|
|
|
mid_mfn = alloc_p2m_page();
|
|
|
|
|
if (!mid_mfn)
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
p2m_mid_mfn_init(mid_mfn);
|
|
|
|
|
|
|
|
|
|
missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
|
|
|
|
|
mid_mfn_mfn = virt_to_mfn(mid_mfn);
|
|
|
|
|
if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
|
|
|
|
|
free_p2m_page(mid_mfn);
|
|
|
|
|
else
|
|
|
|
|
p2m_top_mfn_p[topidx] = mid_mfn;
|
|
|
|
|
}
|
|
|
|
|
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
if (p2m_top[topidx][mididx] == p2m_identity ||
|
|
|
|
|
p2m_top[topidx][mididx] == p2m_missing) {
|
2010-12-07 08:29:22 +08:00
|
|
|
/* p2m leaf page is missing */
|
|
|
|
|
unsigned long *p2m;
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
unsigned long *p2m_orig = p2m_top[topidx][mididx];
|
2010-12-07 08:29:22 +08:00
|
|
|
|
|
|
|
|
p2m = alloc_p2m_page();
|
|
|
|
|
if (!p2m)
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
p2m_init(p2m);
|
|
|
|
|
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
|
2010-12-07 08:29:22 +08:00
|
|
|
free_p2m_page(p2m);
|
|
|
|
|
else
|
|
|
|
|
mid_mfn[mididx] = virt_to_mfn(p2m);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return true;
|
|
|
|
|
}
|
|
|
|
|
|
2011-03-25 04:34:32 +08:00
|
|
|
static bool __init __early_alloc_p2m(unsigned long pfn)
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
{
|
|
|
|
|
unsigned topidx, mididx, idx;
|
|
|
|
|
|
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
|
|
|
mididx = p2m_mid_index(pfn);
|
|
|
|
|
idx = p2m_index(pfn);
|
|
|
|
|
|
|
|
|
|
/* Pfff.. No boundary cross-over, lets get out. */
|
|
|
|
|
if (!idx)
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
WARN(p2m_top[topidx][mididx] == p2m_identity,
|
|
|
|
|
"P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n",
|
|
|
|
|
topidx, mididx);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Could be done by xen_build_dynamic_phys_to_machine..
|
|
|
|
|
*/
|
|
|
|
|
if (p2m_top[topidx][mididx] != p2m_missing)
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
/* Boundary cross-over for the edges: */
|
|
|
|
|
if (idx) {
|
|
|
|
|
unsigned long *p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
|
|
|
|
|
p2m_init(p2m);
|
|
|
|
|
|
|
|
|
|
p2m_top[topidx][mididx] = p2m;
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
return idx != 0;
|
|
|
|
|
}
|
2011-03-25 04:34:32 +08:00
|
|
|
unsigned long __init set_phys_range_identity(unsigned long pfn_s,
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
unsigned long pfn_e)
|
|
|
|
|
{
|
|
|
|
|
unsigned long pfn;
|
|
|
|
|
|
|
|
|
|
if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN))
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
|
|
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
|
|
|
|
|
return pfn_e - pfn_s;
|
|
|
|
|
|
|
|
|
|
if (pfn_s > pfn_e)
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
|
|
for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1));
|
|
|
|
|
pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE));
|
|
|
|
|
pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE)
|
|
|
|
|
{
|
|
|
|
|
unsigned topidx = p2m_top_index(pfn);
|
|
|
|
|
if (p2m_top[topidx] == p2m_mid_missing) {
|
|
|
|
|
unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
|
|
|
|
|
|
|
|
|
|
p2m_mid_init(mid);
|
|
|
|
|
|
|
|
|
|
p2m_top[topidx] = mid;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
__early_alloc_p2m(pfn_s);
|
|
|
|
|
__early_alloc_p2m(pfn_e);
|
|
|
|
|
|
|
|
|
|
for (pfn = pfn_s; pfn < pfn_e; pfn++)
|
|
|
|
|
if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn)))
|
|
|
|
|
break;
|
|
|
|
|
|
|
|
|
|
if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s),
|
|
|
|
|
"Identity mapping failed. We are %ld short of 1-1 mappings!\n",
|
|
|
|
|
(pfn_e - pfn_s) - (pfn - pfn_s)))
|
|
|
|
|
printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn);
|
|
|
|
|
|
|
|
|
|
return pfn - pfn_s;
|
|
|
|
|
}
|
|
|
|
|
|
2010-12-07 08:29:22 +08:00
|
|
|
/* Try to install p2m mapping; fail if intermediate bits missing */
|
|
|
|
|
bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
|
|
|
|
|
{
|
|
|
|
|
unsigned topidx, mididx, idx;
|
|
|
|
|
|
2011-01-19 09:09:41 +08:00
|
|
|
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
|
|
|
|
|
BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
|
|
|
|
|
return true;
|
|
|
|
|
}
|
2010-12-07 08:29:22 +08:00
|
|
|
if (unlikely(pfn >= MAX_P2M_PFN)) {
|
|
|
|
|
BUG_ON(mfn != INVALID_P2M_ENTRY);
|
|
|
|
|
return true;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
topidx = p2m_top_index(pfn);
|
|
|
|
|
mididx = p2m_mid_index(pfn);
|
|
|
|
|
idx = p2m_index(pfn);
|
|
|
|
|
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
/* For sparse holes were the p2m leaf has real PFN along with
|
|
|
|
|
* PCI holes, stick in the PFN as the MFN value.
|
|
|
|
|
*/
|
|
|
|
|
if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) {
|
|
|
|
|
if (p2m_top[topidx][mididx] == p2m_identity)
|
|
|
|
|
return true;
|
|
|
|
|
|
|
|
|
|
/* Swap over from MISSING to IDENTITY if needed. */
|
|
|
|
|
if (p2m_top[topidx][mididx] == p2m_missing) {
|
2011-01-19 09:17:10 +08:00
|
|
|
WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
|
|
|
|
|
p2m_identity) != p2m_missing);
|
xen/mmu: Add the notion of identity (1-1) mapping.
Our P2M tree structure is a three-level. On the leaf nodes
we set the Machine Frame Number (MFN) of the PFN. What this means
is that when one does: pfn_to_mfn(pfn), which is used when creating
PTE entries, you get the real MFN of the hardware. When Xen sets
up a guest it initially populates a array which has descending
(or ascending) MFN values, as so:
idx: 0, 1, 2
[0x290F, 0x290E, 0x290D, ..]
so pfn_to_mfn(2)==0x290D. If you start, restart many guests that list
starts looking quite random.
We graft this structure on our P2M tree structure and stick in
those MFN in the leafs. But for all other leaf entries, or for the top
root, or middle one, for which there is a void entry, we assume it is
"missing". So
pfn_to_mfn(0xc0000)=INVALID_P2M_ENTRY.
We add the possibility of setting 1-1 mappings on certain regions, so
that:
pfn_to_mfn(0xc0000)=0xc0000
The benefit of this is, that we can assume for non-RAM regions (think
PCI BARs, or ACPI spaces), we can create mappings easily b/c we
get the PFN value to match the MFN.
For this to work efficiently we introduce one new page p2m_identity and
allocate (via reserved_brk) any other pages we need to cover the sides
(1GB or 4MB boundary violations). All entries in p2m_identity are set to
INVALID_P2M_ENTRY type (Xen toolstack only recognizes that and MFNs,
no other fancy value).
On lookup we spot that the entry points to p2m_identity and return the identity
value instead of dereferencing and returning INVALID_P2M_ENTRY. If the entry
points to an allocated page, we just proceed as before and return the PFN.
If the PFN has IDENTITY_FRAME_BIT set we unmask that in appropriate functions
(pfn_to_mfn).
The reason for having the IDENTITY_FRAME_BIT instead of just returning the
PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
non-identity pfn. To protect ourselves against we elect to set (and get) the
IDENTITY_FRAME_BIT on all identity mapped PFNs.
This simplistic diagram is used to explain the more subtle piece of code.
There is also a digram of the P2M at the end that can help.
Imagine your E820 looking as so:
1GB 2GB
/-------------------+---------\/----\ /----------\ /---+-----\
| System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
\-------------------+---------/\----/ \----------/ \---+-----/
^- 1029MB ^- 2001MB
[1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100), 2048MB = 524288 (0x80000)]
And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
is actually not present (would have to kick the balloon driver to put it in).
When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
of the PFN and the end PFN (263424 and 512256 respectively). The first step is
to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
covers 512^2 of page estate (1GB) and in case the start or end PFN is not
aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn to
end pfn. We reserve_brk top leaf pages if they are missing (means they point
to p2m_mid_missing).
With the E820 example above, 263424 is not 1GB aligned so we allocate a
reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
Each entry in the allocate page is "missing" (points to p2m_missing).
Next stage is to determine if we need to do a more granular boundary check
on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
We check if the start pfn and end pfn violate that boundary check, and if
so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
granularity of setting which PFNs are missing and which ones are identity.
In our example 263424 and 512256 both fail the check so we reserve_brk two
pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing" values)
and assign them to p2m[1][2] and p2m[1][488] respectively.
At this point we would at minimum reserve_brk one page, but could be up to
three. Each call to set_phys_range_identity has at maximum a three page
cost. If we were to query the P2M at this stage, all those entries from
start PFN through end PFN (so 1029MB -> 2001MB) would return INVALID_P2M_ENTRY
("missing").
The next step is to walk from the start pfn to the end pfn setting
the IDENTITY_FRAME_BIT on each PFN. This is done in 'set_phys_range_identity'.
If we find that the middle leaf is pointing to p2m_missing we can swap it over
to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this point we
do not need to worry about boundary aligment (so no need to reserve_brk a middle
page, figure out which PFNs are "missing" and which ones are identity), as that
has been done earlier. If we find that the middle leaf is not occupied by
p2m_identity or p2m_missing, we dereference that page (which covers
512 PFNs) and set the appropriate PFN with IDENTITY_FRAME_BIT. In our example
263424 and 512256 end up there, and we set from p2m[1][2][256->511] and
p2m[1][488][0->256] with IDENTITY_FRAME_BIT set.
All other regions that are void (or not filled) either point to p2m_missing
(considered missing) or have the default value of INVALID_P2M_ENTRY (also
considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
contain the INVALID_P2M_ENTRY value and are considered "missing."
This is what the p2m ends up looking (for the E820 above) with this
fabulous drawing:
p2m /--------------\
/-----\ | &mfn_list[0],| /-----------------\
| 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
|-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
| 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
|-----| \ | [p2m_identity]+\\ | .... |
| 2 |--\ \-------------------->| ... | \\ \----------------/
|-----| \ \---------------/ \\
| 3 |\ \ \\ p2m_identity
|-----| \ \-------------------->/---------------\ /-----------------\
| .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
\-----/ / | [p2m_identity]+-->| ..., ~0 |
/ /---------------\ | .... | \-----------------/
/ | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
/ | IDENTITY[@256]|<----/ \---------------/
/ | ~0, ~0, .... |
| \---------------/
|
p2m_missing p2m_missing
/------------------\ /------------\
| [p2m_mid_missing]+---->| ~0, ~0, ~0 |
| [p2m_mid_missing]+---->| ..., ~0 |
\------------------/ \------------/
where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
[v5: Changed code to use ranges, added ASCII art]
[v6: Rebased on top of xen->p2m code split]
[v4: Squished patches in just this one]
[v7: Added RESERVE_BRK for potentially allocated pages]
[v8: Fixed alignment problem]
[v9: Changed 1<<3X to 1<<BITS_PER_LONG-X]
[v10: Copied git commit description in the p2m code + Add Review tag]
[v11: Title had '2-1' - should be '1-1' mapping]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-01-19 09:15:21 +08:00
|
|
|
return true;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
2010-12-07 08:29:22 +08:00
|
|
|
if (p2m_top[topidx][mididx] == p2m_missing)
|
|
|
|
|
return mfn == INVALID_P2M_ENTRY;
|
|
|
|
|
|
|
|
|
|
p2m_top[topidx][mididx][idx] = mfn;
|
|
|
|
|
|
|
|
|
|
return true;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
|
|
|
|
|
{
|
|
|
|
|
if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
|
|
|
|
|
if (!alloc_p2m(pfn))
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
if (!__set_phys_to_machine(pfn, mfn))
|
|
|
|
|
return false;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return true;
|
|
|
|
|
}
|
2010-12-15 21:19:33 +08:00
|
|
|
|
|
|
|
|
#define M2P_OVERRIDE_HASH_SHIFT 10
|
|
|
|
|
#define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT)
|
|
|
|
|
|
|
|
|
|
static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
|
|
|
|
|
static DEFINE_SPINLOCK(m2p_override_lock);
|
|
|
|
|
|
|
|
|
|
static void __init m2p_override_init(void)
|
|
|
|
|
{
|
|
|
|
|
unsigned i;
|
|
|
|
|
|
|
|
|
|
m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
|
|
|
|
|
sizeof(unsigned long));
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < M2P_OVERRIDE_HASH; i++)
|
|
|
|
|
INIT_LIST_HEAD(&m2p_overrides[i]);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static unsigned long mfn_hash(unsigned long mfn)
|
|
|
|
|
{
|
|
|
|
|
return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* Add an MFN override for a particular page */
|
2011-03-01 06:58:48 +08:00
|
|
|
int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte)
|
2010-12-15 21:19:33 +08:00
|
|
|
{
|
|
|
|
|
unsigned long flags;
|
2010-12-13 22:42:30 +08:00
|
|
|
unsigned long pfn;
|
2011-02-11 23:23:58 +08:00
|
|
|
unsigned long uninitialized_var(address);
|
2010-12-13 22:42:30 +08:00
|
|
|
unsigned level;
|
|
|
|
|
pte_t *ptep = NULL;
|
|
|
|
|
|
|
|
|
|
pfn = page_to_pfn(page);
|
|
|
|
|
if (!PageHighMem(page)) {
|
|
|
|
|
address = (unsigned long)__va(pfn << PAGE_SHIFT);
|
|
|
|
|
ptep = lookup_address(address, &level);
|
|
|
|
|
if (WARN(ptep == NULL || level != PG_LEVEL_4K,
|
|
|
|
|
"m2p_add_override: pfn %lx not mapped", pfn))
|
|
|
|
|
return -EINVAL;
|
|
|
|
|
}
|
|
|
|
|
|
2010-12-15 21:19:33 +08:00
|
|
|
page->private = mfn;
|
2010-12-10 22:52:45 +08:00
|
|
|
page->index = pfn_to_mfn(pfn);
|
2010-12-15 21:19:33 +08:00
|
|
|
|
2011-03-24 20:10:07 +08:00
|
|
|
if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
|
|
|
|
|
return -ENOMEM;
|
|
|
|
|
|
2011-03-01 06:58:48 +08:00
|
|
|
if (clear_pte && !PageHighMem(page))
|
2010-12-13 22:42:30 +08:00
|
|
|
/* Just zap old mapping for now */
|
|
|
|
|
pte_clear(&init_mm, address, ptep);
|
2010-12-15 21:19:33 +08:00
|
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
|
|
|
list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
|
|
|
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
2010-12-13 22:42:30 +08:00
|
|
|
|
|
|
|
|
return 0;
|
2010-12-15 21:19:33 +08:00
|
|
|
}
|
|
|
|
|
|
2011-03-01 06:58:48 +08:00
|
|
|
int m2p_remove_override(struct page *page, bool clear_pte)
|
2010-12-15 21:19:33 +08:00
|
|
|
{
|
|
|
|
|
unsigned long flags;
|
2010-12-10 22:52:45 +08:00
|
|
|
unsigned long mfn;
|
|
|
|
|
unsigned long pfn;
|
2011-02-11 23:23:58 +08:00
|
|
|
unsigned long uninitialized_var(address);
|
2010-12-13 22:42:30 +08:00
|
|
|
unsigned level;
|
|
|
|
|
pte_t *ptep = NULL;
|
2010-12-10 22:52:45 +08:00
|
|
|
|
|
|
|
|
pfn = page_to_pfn(page);
|
|
|
|
|
mfn = get_phys_to_machine(pfn);
|
|
|
|
|
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
|
2010-12-13 22:42:30 +08:00
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
|
|
if (!PageHighMem(page)) {
|
|
|
|
|
address = (unsigned long)__va(pfn << PAGE_SHIFT);
|
|
|
|
|
ptep = lookup_address(address, &level);
|
|
|
|
|
|
|
|
|
|
if (WARN(ptep == NULL || level != PG_LEVEL_4K,
|
|
|
|
|
"m2p_remove_override: pfn %lx not mapped", pfn))
|
|
|
|
|
return -EINVAL;
|
|
|
|
|
}
|
2010-12-10 22:52:45 +08:00
|
|
|
|
2010-12-15 21:19:33 +08:00
|
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
|
|
|
list_del(&page->lru);
|
|
|
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
2011-03-24 20:10:07 +08:00
|
|
|
set_phys_to_machine(pfn, page->index);
|
2010-12-13 22:42:30 +08:00
|
|
|
|
2011-03-01 06:58:48 +08:00
|
|
|
if (clear_pte && !PageHighMem(page))
|
2010-12-13 22:42:30 +08:00
|
|
|
set_pte_at(&init_mm, address, ptep,
|
|
|
|
|
pfn_pte(pfn, PAGE_KERNEL));
|
|
|
|
|
/* No tlb flush necessary because the caller already
|
|
|
|
|
* left the pte unmapped. */
|
|
|
|
|
|
|
|
|
|
return 0;
|
2010-12-15 21:19:33 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
struct page *m2p_find_override(unsigned long mfn)
|
|
|
|
|
{
|
|
|
|
|
unsigned long flags;
|
|
|
|
|
struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
|
|
|
|
|
struct page *p, *ret;
|
|
|
|
|
|
|
|
|
|
ret = NULL;
|
|
|
|
|
|
|
|
|
|
spin_lock_irqsave(&m2p_override_lock, flags);
|
|
|
|
|
|
|
|
|
|
list_for_each_entry(p, bucket, lru) {
|
|
|
|
|
if (p->private == mfn) {
|
|
|
|
|
ret = p;
|
|
|
|
|
break;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
spin_unlock_irqrestore(&m2p_override_lock, flags);
|
|
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
struct page *p = m2p_find_override(mfn);
|
|
|
|
|
unsigned long ret = pfn;
|
|
|
|
|
|
|
|
|
|
if (p)
|
|
|
|
|
ret = page_to_pfn(p);
|
|
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
|
}
|
2011-01-12 04:09:16 +08:00
|
|
|
EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
|
2010-12-22 21:57:30 +08:00
|
|
|
|
|
|
|
|
#ifdef CONFIG_XEN_DEBUG_FS
|
|
|
|
|
|
|
|
|
|
int p2m_dump_show(struct seq_file *m, void *v)
|
|
|
|
|
{
|
|
|
|
|
static const char * const level_name[] = { "top", "middle",
|
|
|
|
|
"entry", "abnormal" };
|
|
|
|
|
static const char * const type_name[] = { "identity", "missing",
|
|
|
|
|
"pfn", "abnormal"};
|
|
|
|
|
#define TYPE_IDENTITY 0
|
|
|
|
|
#define TYPE_MISSING 1
|
|
|
|
|
#define TYPE_PFN 2
|
|
|
|
|
#define TYPE_UNKNOWN 3
|
|
|
|
|
unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0;
|
|
|
|
|
unsigned int uninitialized_var(prev_level);
|
|
|
|
|
unsigned int uninitialized_var(prev_type);
|
|
|
|
|
|
|
|
|
|
if (!p2m_top)
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
|
|
for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) {
|
|
|
|
|
unsigned topidx = p2m_top_index(pfn);
|
|
|
|
|
unsigned mididx = p2m_mid_index(pfn);
|
|
|
|
|
unsigned idx = p2m_index(pfn);
|
|
|
|
|
unsigned lvl, type;
|
|
|
|
|
|
|
|
|
|
lvl = 4;
|
|
|
|
|
type = TYPE_UNKNOWN;
|
|
|
|
|
if (p2m_top[topidx] == p2m_mid_missing) {
|
|
|
|
|
lvl = 0; type = TYPE_MISSING;
|
|
|
|
|
} else if (p2m_top[topidx] == NULL) {
|
|
|
|
|
lvl = 0; type = TYPE_UNKNOWN;
|
|
|
|
|
} else if (p2m_top[topidx][mididx] == NULL) {
|
|
|
|
|
lvl = 1; type = TYPE_UNKNOWN;
|
|
|
|
|
} else if (p2m_top[topidx][mididx] == p2m_identity) {
|
|
|
|
|
lvl = 1; type = TYPE_IDENTITY;
|
|
|
|
|
} else if (p2m_top[topidx][mididx] == p2m_missing) {
|
|
|
|
|
lvl = 1; type = TYPE_MISSING;
|
|
|
|
|
} else if (p2m_top[topidx][mididx][idx] == 0) {
|
|
|
|
|
lvl = 2; type = TYPE_UNKNOWN;
|
|
|
|
|
} else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) {
|
|
|
|
|
lvl = 2; type = TYPE_IDENTITY;
|
|
|
|
|
} else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) {
|
|
|
|
|
lvl = 2; type = TYPE_MISSING;
|
|
|
|
|
} else if (p2m_top[topidx][mididx][idx] == pfn) {
|
|
|
|
|
lvl = 2; type = TYPE_PFN;
|
|
|
|
|
} else if (p2m_top[topidx][mididx][idx] != pfn) {
|
|
|
|
|
lvl = 2; type = TYPE_PFN;
|
|
|
|
|
}
|
|
|
|
|
if (pfn == 0) {
|
|
|
|
|
prev_level = lvl;
|
|
|
|
|
prev_type = type;
|
|
|
|
|
}
|
|
|
|
|
if (pfn == MAX_DOMAIN_PAGES-1) {
|
|
|
|
|
lvl = 3;
|
|
|
|
|
type = TYPE_UNKNOWN;
|
|
|
|
|
}
|
|
|
|
|
if (prev_type != type) {
|
|
|
|
|
seq_printf(m, " [0x%lx->0x%lx] %s\n",
|
|
|
|
|
prev_pfn_type, pfn, type_name[prev_type]);
|
|
|
|
|
prev_pfn_type = pfn;
|
|
|
|
|
prev_type = type;
|
|
|
|
|
}
|
|
|
|
|
if (prev_level != lvl) {
|
|
|
|
|
seq_printf(m, " [0x%lx->0x%lx] level %s\n",
|
|
|
|
|
prev_pfn_level, pfn, level_name[prev_level]);
|
|
|
|
|
prev_pfn_level = pfn;
|
|
|
|
|
prev_level = lvl;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
return 0;
|
|
|
|
|
#undef TYPE_IDENTITY
|
|
|
|
|
#undef TYPE_MISSING
|
|
|
|
|
#undef TYPE_PFN
|
|
|
|
|
#undef TYPE_UNKNOWN
|
|
|
|
|
}
|
|
|
|
|
#endif
|