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KVM: MTRR: do not map huge page for non-consistent range

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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>
This commit is contained in:
Xiao Guangrong
2015-06-15 16:55:35 +08:00
committed by Paolo Bonzini
parent fa61213746
commit 6a39bbc5da
3 changed files with 50 additions and 1 deletions
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20
arch/x86/kvm/mmu.c
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@@ -3446,6 +3446,16 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
return false;
}
static bool
check_hugepage_cache_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, int level)
{
int page_num = KVM_PAGES_PER_HPAGE(level);
gfn &= ~(page_num - 1);
return kvm_mtrr_check_gfn_range_consistency(vcpu, gfn, page_num);
}
static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
bool prefault)
{
@@ -3471,9 +3481,17 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
if (r)
return r;
force_pt_level = mapping_level_dirty_bitmap(vcpu, gfn);
if (mapping_level_dirty_bitmap(vcpu, gfn) ||
!check_hugepage_cache_consistency(vcpu, gfn, PT_DIRECTORY_LEVEL))
force_pt_level = 1;
else
force_pt_level = 0;
if (likely(!force_pt_level)) {
level = mapping_level(vcpu, gfn);
if (level > PT_DIRECTORY_LEVEL &&
!check_hugepage_cache_consistency(vcpu, gfn, level))
level = PT_DIRECTORY_LEVEL;
gfn &= ~(KVM_PAGES_PER_HPAGE(level) - 1);
} else
level = PT_PAGE_TABLE_LEVEL;