diff options
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 5957c3e66b77..7c0b10aac3ed 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4296,14 +4296,26 @@ EXPORT_SYMBOL_GPL(kvm_handle_page_fault); int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { - while (fault->max_level > PG_LEVEL_4K) { - int page_num = KVM_PAGES_PER_HPAGE(fault->max_level); - gfn_t base = (fault->addr >> PAGE_SHIFT) & ~(page_num - 1); - - if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num)) - break; + /* + * If the guest's MTRRs may be used to compute the "real" memtype, + * restrict the mapping level to ensure KVM uses a consistent memtype + * across the entire mapping. If the host MTRRs are ignored by TDP + * (shadow_memtype_mask is non-zero), and the VM has non-coherent DMA + * (DMA doesn't snoop CPU caches), KVM's ABI is to honor the memtype + * from the guest's MTRRs so that guest accesses to memory that is + * DMA'd aren't cached against the guest's wishes. + * + * Note, KVM may still ultimately ignore guest MTRRs for certain PFNs, + * e.g. KVM will force UC memtype for host MMIO. + */ + if (shadow_memtype_mask && kvm_arch_has_noncoherent_dma(vcpu->kvm)) { + for ( ; fault->max_level > PG_LEVEL_4K; --fault->max_level) { + int page_num = KVM_PAGES_PER_HPAGE(fault->max_level); + gfn_t base = (fault->addr >> PAGE_SHIFT) & ~(page_num - 1); - --fault->max_level; + if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num)) + break; + } } return direct_page_fault(vcpu, fault); |