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Subject[PATCH AUTOSEL 4.19 135/167] KVM: VMX: check CPUID before allowing read/write of IA32_XSS
Date
From: Wanpeng Li <wanpengli@tencent.com>

[ Upstream commit 4d763b168e9c5c366b05812c7bba7662e5ea3669 ]

Raise #GP when guest read/write IA32_XSS, but the CPUID bits
say that it shouldn't exist.

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: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kvm/vmx.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 82253d31842a2..2938b4bcc9684 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4135,7 +4135,10 @@ 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;
@@ -4302,7 +4305,10 @@ 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
--
2.20.1
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