Userspace that does not know about the AMD_IBRS bit might still
allow the guest to protect itself with MSR_IA32_SPEC_CTRL using
the Intel SPEC_CTRL bit. However, svm.c disallows this and will
cause a #GP in the guest when writing to the MSR. Fix this by
loosening the test and allowing the Intel CPUID bit, and in fact
allow the AMD_STIBP bit as well since it allows writing to
MSR_IA32_SPEC_CTRL too.
Reported-by: Zhiyi Guo <zhguo@redhat.com>
Analyzed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Analyzed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
break;
case MSR_IA32_SPEC_CTRL:
if (!msr_info->host_initiated &&
break;
case MSR_IA32_SPEC_CTRL:
if (!msr_info->host_initiated &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
return 1;
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
return 1;
break;
case MSR_IA32_SPEC_CTRL:
if (!msr->host_initiated &&
break;
case MSR_IA32_SPEC_CTRL:
if (!msr->host_initiated &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL) &&
+ !guest_cpuid_has(vcpu, X86_FEATURE_AMD_STIBP) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
return 1;
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_IBRS) &&
!guest_cpuid_has(vcpu, X86_FEATURE_AMD_SSBD))
return 1;