Commit Graph

16 Commits

Author SHA1 Message Date
Robin Murphy 2984f7f3bb Revert "iommu/io-pgtable: Avoid redundant TLB syncs"
The tlb_sync_pending flag was necessary for correctness in the Mediatek
M4U driver, but since it offered a small theoretical optimisation for
all io-pgtable users it was implemented as a high-level thing. However,
now that some users may not be using a synchronising lock, there are
several ways this flag can go wrong for them, and at worst it could
result in incorrect behaviour.

Since we've addressed the correctness issue within the Mediatek driver
itself, and fixing the optimisation aspect to be concurrency-safe would
be quite a headache (and impose extra overhead on every operation for
the sake of slightly helping one case which will virtually never happen
in typical usage), let's just retire it.

This reverts commit 88492a4700.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-07-20 10:30:27 +01:00
Robin Murphy 81b3c25218 iommu/io-pgtable: Introduce explicit coherency
Once we remove the serialising spinlock, a potential race opens up for
non-coherent IOMMUs whereby a caller of .map() can be sure that cache
maintenance has been performed on their new PTE, but will have no
guarantee that such maintenance for table entries above it has actually
completed (e.g. if another CPU took an interrupt immediately after
writing the table entry, but before initiating the DMA sync).

Handling this race safely will add some potentially non-trivial overhead
to installing a table entry, which we would much rather avoid on
coherent systems where it will be unnecessary, and where we are stirivng
to minimise latency by removing the locking in the first place.

To that end, let's introduce an explicit notion of cache-coherency to
io-pgtable, such that we will be able to avoid penalising IOMMUs which
know enough to know when they are coherent.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-06-23 17:58:00 +01:00
Yong Wu 1afe23194d iommu/io-pgtable: Add MTK 4GB mode in Short-descriptor
In MT8173, Normally the first 1GB PA is for the HW SRAM and Regs,
so the PA will be 33bits if the dram size is 4GB. We have a
"DRAM 4GB mode" toggle bit for this. If it's enabled, from CPU's
point of view, the dram PA will be from 0x1_00000000~0x1_ffffffff.

In short descriptor, the pagetable descriptor is always 32bit.
Mediatek extend bit9 in the lvl1 and lvl2 pgtable descriptor
as the 4GB mode.

In the 4GB mode, the bit9 must be set, then M4U help add 0x1_00000000
based on the PA in pagetable. Thus the M4U output address to EMI is
always 33bits(the input address is still 32bits).

We add a special quirk for this MTK-4GB mode. And in the standard
spec, Bit9 in the lvl1 is "IMPLEMENTATION DEFINED", while it's AP[2]
in the lvl2, therefore if this quirk is enabled, NO_PERMS is also
expected.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2016-04-05 15:39:37 +02:00
Robin Murphy 3850db49da iommu/io-pgtable: Rationalise quirk handling
As the number of io-pgtable implementations grows beyond 1, it's time
to rationalise the quirks mechanism before things have a chance to
start getting really ugly and out-of-hand.

To that end:
- Indicate exactly which quirks each format can/does support.
- Fail creating a table if a caller wants unsupported quirks.
- Properly document where each quirk applies and why.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-02-17 14:15:09 +00:00
Robin Murphy 88492a4700 iommu/io-pgtable: Avoid redundant TLB syncs
In certain unmapping situations it is quite possible to end up issuing
back-to-back TLB synchronisations, which at best is a waste of time and
effort, and at worst causes some hardware to get rather confused. Whilst
the pagetable implementations, or the IOMMU drivers, or both, could keep
track of things to avoid this happening, it seems to make the most sense
to prevent code duplication and add some simple state tracking in the
common interface between the two.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-02-17 14:15:09 +00:00
Robin Murphy 507e4c9d19 iommu/io-pgtable: Add helper functions for TLB ops
Add some simple wrappers to avoid having the guts of the TLB operations
spilled all over the page table implementations, and to provide a point
to implement extra common functionality.

Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-02-17 14:15:08 +00:00
Robin Murphy e5fc9753b1 iommu/io-pgtable: Add ARMv7 short descriptor support
Add a nearly-complete ARMv7 short descriptor implementation, omitting
only a few legacy and CPU-centric aspects which shouldn't be necessary
for IOMMU API use anyway.

Reviewed-by: Yong Wu <yong.wu@mediatek.com>
Tested-by: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2016-02-17 14:14:57 +00:00
Robin Murphy fdc3896763 iommu/io-pgtable: Make io_pgtable_ops_to_pgtable() macro common
There is no need to keep a useful accessor for a public structure hidden
away in a private implementation. Move it out alongside the structure
definition so that other implementations may reuse it.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-12-17 12:05:35 +00:00
Robin Murphy 06c610e8f3 iommu/io-pgtable: Indicate granule for TLB maintenance
IOMMU hardware with range-based TLB maintenance commands can work
happily with the iova and size arguments passed via the tlb_add_flush
callback, but for IOMMUs which require separate commands per entry in
the range, it is not straightforward to infer the necessary granularity
when it comes to issuing the actual commands.

Add an additional argument indicating the granularity for the benefit
of drivers needing to know, and update the ARM LPAE code appropriately
(for non-leaf invalidations we currently just assume the worst-case
page granularity rather than walking the table to check).

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-12-17 12:05:34 +00:00
Joerg Roedel 2e169bb3cc iommu/io-pgtable-arm: Move init-fn declarations to io-pgtable.h
Avoid extern declarations in c files.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
2015-08-13 19:51:04 +02:00
Robin Murphy f5b831907d iommu/io-pgtable: Remove flush_pgtable callback
With the users fully converted to DMA API operations, it's dead, Jim.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-08-06 14:35:40 +01:00
Robin Murphy 87a91b15d6 iommu/io-pgtable-arm: Centralise sync points
With all current users now opted in to DMA API operations, make the
iommu_dev pointer mandatory, rendering the flush_pgtable callback
redundant for cache maintenance. However, since the DMA calls could be
nops in the case of a coherent IOMMU, we still need to ensure the page
table updates are fully synchronised against a subsequent page table
walk. In the unmap path, the TLB sync will usually need to do this
anyway, so just cement that requirement; in the map path which may
consist solely of cacheable memory writes (in the coherent case),
insert an appropriate barrier at the end of the operation, and obviate
the need to call flush_pgtable on every individual update for
synchronisation.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: slight clarification to tlb_sync comment]
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-08-06 14:35:39 +01:00
Robin Murphy f8d5496131 iommu/io-pgtable-arm: Allow appropriate DMA API use
Currently, users of the LPAE page table code are (ab)using dma_map_page()
as a means to flush page table updates for non-coherent IOMMUs. Since
from the CPU's point of view, creating IOMMU page tables *is* passing
DMA buffers to a device (the IOMMU's page table walker), there's little
reason not to use the DMA API correctly.

Allow IOMMU drivers to opt into DMA API operations for page table
allocation and updates by providing their appropriate device pointer.
The expectation is that an LPAE IOMMU should have a full view of system
memory, so use streaming mappings to avoid unnecessary pressure on
ZONE_DMA, and treat any DMA translation as a warning sign.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-08-06 14:35:38 +01:00
Laurent Pinchart c896c132b0 iommu: io-pgtable-arm: add non-secure quirk
The quirk causes the Non-Secure bit to be set in all page table entries.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-01-19 14:46:45 +00:00
Will Deacon e1d3c0fd70 iommu: add ARM LPAE page table allocator
A number of IOMMUs found in ARM SoCs can walk architecture-compatible
page tables.

This patch adds a generic allocator for Stage-1 and Stage-2 v7/v8
long-descriptor page tables. 4k, 16k and 64k pages are supported, with
up to 4-levels of walk to cover a 48-bit address space.

Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-01-19 14:46:44 +00:00
Will Deacon fdb1d7be7c iommu: introduce generic page table allocation framework
This patch introduces a generic framework for allocating page tables for
an IOMMU. There are a number of reasons we want to do this:

  - It avoids duplication of complex table management code in IOMMU
    drivers that use the same page table format

  - It removes any coupling with the CPU table format (and even the
    architecture!)

  - It defines an API for IOMMU TLB maintenance

Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-01-19 14:46:43 +00:00