From: Sean Christopherson <seanjc@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Message-Id: <20210609234235.1244004-4-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 d3774d79916d..618dcf11d688 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5472,8 +5472,6 @@ 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))
@@ -5482,13 +5480,10 @@ 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
@@ -5497,8 +5492,6 @@ 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);
--
2.30.2
