Virtual machines can be run with CPUID such that there are no MTRRs.
In that case, the firmware will never enable MTRRs and it is obviously
undesirable to run the guest entirely with UC memory. Check out guest
CPUID, and use WB memory if MTRR do not exist.
Cc: qemu-stable@nongnu.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=107561
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Conversion of MTRRs to ranges used the maxphyaddr from the boot CPU.
This is wrong, because var_mtrr_range's mask variable then is discontiguous
(like FF00FFFF000, where the first run of 0s corresponds to the bits
between host and guest maxphyaddr). Instead always set up the masks
to be full 64-bit values---we know that the reserved bits at the top
are zero, and we can restore them when reading the MSR. This way
var_mtrr_range gets a mask that just works.
Fixes: a13842dc66
Cc: qemu-stable@nongnu.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=107561
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This fixes the slow-down of VM running with pci-passthrough, since some MTRR
range changed from MTRR_TYPE_WRBACK to MTRR_TYPE_UNCACHABLE. Memory in the
0K-640K range was incorrectly treated as uncacheable.
Fixes: f7bfb57b3e
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=107561
Cc: qemu-stable@nongnu.org
Signed-off-by: Alexis Dambricourt <alexis.dambricourt@gmail.com>
[Use correct BZ for "Fixes" annotation. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The patch was munged on commit to re-order these tests resulting in
excessive warnings when trying to do device assignment. Return to
original ordering: https://lkml.org/lkml/2015/7/15/769
Fixes: 3e5d2fdced ("KVM: MTRR: simplify kvm_mtrr_get_guest_memory_type")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
kvm_mtrr_get_guest_memory_type never returns -1 which is implied
in the current code since if @type = -1 (means no MTRR contains the
range), iter.partial_map must be true
Simplify the code to indicate this fact
Signed-off-by: Xiao Guangrong <guangrong.xiao@intel.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently code uses default memory type if MTRR is fully disabled,
fix it by using UC instead.
Signed-off-by: Xiao Guangrong <guangrong.xiao@intel.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Based on Intel's SDM, mapping huge page which do not have consistent
memory cache for each 4k page will cause undefined behavior
In order to avoiding this kind of undefined behavior, we force to use
4k pages under this case
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
mtrr_for_each_mem_type() is ready now, use it to simplify
kvm_mtrr_get_guest_memory_type()
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It walks all MTRRs and gets all the memory cache type setting for the
specified range also it checks if the range is fully covered by MTRRs
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
[Adjust for range_size->range_shift change. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Two functions are introduced:
- fixed_mtrr_addr_to_seg() translates the address to the fixed
MTRR segment
- fixed_mtrr_addr_seg_to_range_index() translates the address to
the index of kvm_mtrr.fixed_ranges[]
They will be used in the later patch
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
[Adjust for range_size->range_shift change. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Sort all valid variable MTRRs based on its base address, it will help us to
check a range to see if it's fully contained in variable MTRRs
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
[Fix list insertion sort, simplify var_mtrr_range_is_valid to just
test the V bit. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It gets the range for the specified variable MTRR
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
[Simplify boolean operations. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This table summarizes the information of fixed MTRRs and introduce some APIs
to abstract its operation which helps us to clean up the code and will be
used in later patches
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
[Change range_size to range_shift, in order to avoid udivdi3 errors.
- Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- kvm_mtrr_get_guest_memory_type() only checks one page in MTRRs so
that it's unnecessary to check to see if the range is partially
covered in MTRR
- optimize the check of overlap memory type and add some comments
to explain the precedence
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Variable MTRR MSRs are 64 bits which are directly accessed with full length,
no reason to split them to two 32 bits
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop kvm_mtrr->enable, omit the decode/code workload and get rid of
all the hard code
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
vMTRR does not depend on any host MTRR feature and fixed MTRRs have always
been implemented, so drop this field
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MSR_MTRRcap is a MTRR msr so move the handler to the common place, also
add some comments to make the hard code more readable
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MTRR code locates in x86.c and mmu.c so that move them to a separate file to
make the organization more clearer and it will be the place where we fully
implement vMTRR
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo Bonzini