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authorMarc Orr <marcorr@google.com>2019-04-01 23:56:00 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-04-17 08:38:55 +0200
commit59bf185ae6b7d1a7ec2d7ff312b94df787ebcb11 (patch)
tree940c50890e91f2983f8871e72cee7e4663e5b607
parent119031be7b0a2ce4ff4cd5525bec6d42817ff53d (diff)
KVM: x86: nVMX: fix x2APIC VTPR read intercept
commit c73f4c998e1fd4249b9edfa39e23f4fda2b9b041 upstream. 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 <marcorr@google.com> Reviewed-by: Jim Mattson <jmattson@google.com> Fixes: c992384bde84f ("KVM: vmx: speed up MSR bitmap merge") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/vmx.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 440b9587bedb..6b6bcafd1d2c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11660,7 +11660,7 @@ 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(