The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4d763b168e9c5c366b05812c7bba7662e5ea3669 Mon Sep 17 00:00:00 2001

From: Wanpeng Li wanpengli@tencent.com Date: Thu, 20 Jun 2019 17:00:02 +0800 Subject: [PATCH] KVM: VMX: check CPUID before allowing read/write of IA32_XSS MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index b939a688ae83..a35459ce7e29 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