From: Sean Christopherson seanjc@google.com
[ Upstream commit 272b0a998d084e7667284bdd2d0c675c6a2d11de ]
Drop bogus logic that incorrectly clobbers the accessed/dirty enabling status of the nested MMU on an EPTP switch. When nested EPT is enabled, walk_mmu points at L2's _legacy_ page tables, not L1's EPT for L2.
This is likely a benign bug, as mmu->ept_ad is never consumed (since the MMU is not a nested EPT MMU), and stuffing mmu_role.base.ad_disabled will never propagate into future shadow pages since the nested MMU isn't used to map anything, just to walk L2's page tables.
Note, KVM also does a full MMU reload, i.e. the guest_mmu will be recreated using the new EPTP, and thus any change in A/D enabling will be properly recognized in the relevant MMU.
Fixes: 41ab93727467 ("KVM: nVMX: Emulate EPTP switching for the L1 hypervisor") Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20210609234235.1244004-4-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/vmx/nested.c | 7 ------- 1 file changed, 7 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index ba82b8563b07..2e63171864a7 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5488,8 +5488,6 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu, { u32 index = kvm_rcx_read(vcpu); u64 new_eptp; - bool accessed_dirty; - struct kvm_mmu *mmu = vcpu->arch.walk_mmu;
if (!nested_cpu_has_eptp_switching(vmcs12) || !nested_cpu_has_ept(vmcs12)) @@ -5498,13 +5496,10 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu, if (index >= VMFUNC_EPTP_ENTRIES) return 1;
- if (kvm_vcpu_read_guest_page(vcpu, vmcs12->eptp_list_address >> PAGE_SHIFT, &new_eptp, index * 8, 8)) return 1;
- accessed_dirty = !!(new_eptp & VMX_EPTP_AD_ENABLE_BIT); - /* * If the (L2) guest does a vmfunc to the currently * active ept pointer, we don't have to do anything else @@ -5513,8 +5508,6 @@ static int nested_vmx_eptp_switching(struct kvm_vcpu *vcpu, if (!nested_vmx_check_eptp(vcpu, new_eptp)) return 1;
- mmu->ept_ad = accessed_dirty; - mmu->mmu_role.base.ad_disabled = !accessed_dirty; vmcs12->ept_pointer = new_eptp;
kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu);