From e18a9cc8001ee53c3225f102cfc3510cbcf4cc93 Mon Sep 17 00:00:00 2001 From: Marc Orr Date: Mon, 1 Apr 2019 23:56:00 -0700 Subject: [PATCH] KVM: x86: nVMX: fix x2APIC VTPR read intercept Referring to the "VIRTUALIZING MSR-BASED APIC ACCESSES" chapter of the SDM, when "virtualize x2APIC mode" is 1 and "APIC-register virtualization" is 0, a RDMSR of 808H should return the VTPR from the virtual APIC page. However, for nested, KVM currently fails to disable the read intercept for this MSR. This means that a RDMSR exit takes precedence over "virtualize x2APIC mode", and KVM passes through L1's TPR to L2, instead of sourcing the value from L2's virtual APIC page. This patch fixes the issue by disabling the read intercept, in VMCS02, for the VTPR when "APIC-register virtualization" is 0. The issue described above and fix prescribed here, were verified with a related patch in kvm-unit-tests titled "Test VMX's virtualize x2APIC mode w/ nested". Signed-off-by: Marc Orr Reviewed-by: Jim Mattson Fixes: 424113db115f1 ("KVM: vmx: speed up MSR bitmap merge") Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/nested.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 897d70e3d291d..7ec9bb1dd7231 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -578,7 +578,7 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu, nested_vmx_disable_intercept_for_msr( msr_bitmap_l1, msr_bitmap_l0, X2APIC_MSR(APIC_TASKPRI), - MSR_TYPE_W); + MSR_TYPE_R | MSR_TYPE_W); if (nested_cpu_has_vid(vmcs12)) { nested_vmx_disable_intercept_for_msr( -- 2.39.5