KVM: MTRR: do not map huge page for non-consistent range
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>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 532aad2..f807496 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3446,6 +3446,16 @@
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 @@
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;