[PATCH] KVM: x86: Zap EPT on CD changes when KVM has non-coherent DMA

[Yan Zhao]

Always zap EPT on CD changes when a VM has non-coherent DMA devices
attached, no matter quirk KVM_X86_QUIRK_CD_NW_CLEARED is turned on or not.

Previously when kvm_arch_has_noncoherent_dma() is true, EPT is zapped when
CD is toggled only if quirk KVM_X86_QUIRK_CD_NW_CLEARED is off.

However, EPT should also be zapped when quirk KVM_X86_QUIRK_CD_NW_CLEARED
is on because the EPT memtype would switch bewteen
- "MTRR_TYPE_WRBACK | VMX_EPT_IPAT_BIT", and
- "guest MTRR type (without VMX_EPT_IPAT_BIT)".

Fixes: 879ae1880449 ("KVM: x86: obey KVM_X86_QUIRK_CD_NW_CLEARED in kvm_set_cr0()")
Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
---
 arch/x86/kvm/x86.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 93b0bd45ac73..3e874cfaf059 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -792,8 +792,7 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
                kvm_mmu_reset_context(vcpu);

        if (((cr0 ^ old_cr0) & X86_CR0_CD) &&
-           kvm_arch_has_noncoherent_dma(vcpu->kvm) &&
-           !kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED))
+           kvm_arch_has_noncoherent_dma(vcpu->kvm))
                kvm_zap_gfn_range(vcpu->kvm, 0, ~0ULL);

        return 0;

base-commit: d45331b00ddb179e291766617259261c112db872
--
2.27.0