[PATCH] KVM: VMX: Raise #GP when guest read/write forbidden IA32_XSS

[Wanpeng Li <kernellwp@gmail.com>]

From: Wanpeng Li <wanpengli@tencent.com>

Raise #GP when guest read/write forbidden IA32_XSS.  

Fixes: 203000993de5 (kvm: vmx: add MSR logic for XSAVES) 
Reported-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
Reported-by: Tao Xu <tao3.xu@intel.com>
Cc: Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
 arch/x86/kvm/vmx/vmx.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b939a68..d174b62 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1732,7 +1732,10 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		return vmx_get_vmx_msr(&vmx->nested.msrs, msr_info->index,
 				       &msr_info->data);
 	case MSR_IA32_XSS:
-		if (!vmx_xsaves_supported())
+		if (!vmx_xsaves_supported() ||
+			(!msr_info->host_initiated &&
+			!(guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) &&
+			guest_cpuid_has(vcpu, X86_FEATURE_XSAVES))))
 			return 1;
 		msr_info->data = vcpu->arch.ia32_xss;
 		break;
@@ -1962,7 +1965,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 			return 1;
 		return vmx_set_vmx_msr(vcpu, msr_index, data);
 	case MSR_IA32_XSS:
-		if (!vmx_xsaves_supported())
+		if (!vmx_xsaves_supported() ||
+			(!msr_info->host_initiated &&
+			!(guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) &&
+			guest_cpuid_has(vcpu, X86_FEATURE_XSAVES))))
 			return 1;
 		/*
 		 * The only supported bit as of Skylake is bit 8, but
-- 
2.7.4