@@ -3798,8 +3798,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
vcpu->arch.microcode_version = data;
break;
case MSR_IA32_ARCH_CAPABILITIES:
- if (!msr_info->host_initiated)
- return 1;
+ if (!msr_info->host_initiated ||
+ !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))
+ return KVM_MSR_RET_UNSUPPORTED;
vcpu->arch.arch_capabilities = data;
break;
case MSR_IA32_PERF_CAPABILITIES:
@@ -4259,9 +4260,8 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
msr_info->data = vcpu->arch.microcode_version;
break;
case MSR_IA32_ARCH_CAPABILITIES:
- if (!msr_info->host_initiated &&
- !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))
- return 1;
+ if (!guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))
+ return KVM_MSR_RET_UNSUPPORTED;
msr_info->data = vcpu->arch.arch_capabilities;
break;
case MSR_IA32_PERF_CAPABILITIES:
Reject userspace accesses to ARCH_CAPABILITIES if the MSR isn't supposed to exist, according to guest CPUID. However, "reject" accesses with KVM_MSR_RET_UNSUPPORTED, so that reads get '0' and writes of '0' are ignored if KVM advertised support ARCH_CAPABILITIES. KVM's ABI is that userspace must set guest CPUID prior to setting MSRs, and that setting MSRs that aren't supposed exist is disallowed (modulo the '0' exemption). Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/x86.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)