Commit b467ab82 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: expose MSR_PLATFORM_INFO as a feature MSR 



For userspace that wants to disable KVM_X86_QUIRK_STUFF_FEATURE_MSRS, it
is useful to know what bits can be set to 1 in MSR_PLATFORM_INFO (apart
from the TSC ratio).  The right way to do that is via /dev/kvm's
feature MSR mechanism.

In fact, MSR_PLATFORM_INFO is already a feature MSR for the purpose of
blocking updates after the vCPU is run, but KVM_GET_MSRS did not return
a valid value for it.

Just like in a VM that leaves KVM_X86_QUIRK_STUFF_FEATURE_MSRS enabled,
the TSC ratio field is left to 0.  Only bit 31 is set.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent a0423af9

arch/x86/kvm/x86.c

+3 −0
Original line number Diff line number Diff line
@@ -1675,6 +1675,9 @@ static int kvm_get_feature_msr(struct kvm_vcpu *vcpu, u32 index, u64 *data, 
	case MSR_IA32_PERF_CAPABILITIES:

		*data = kvm_caps.supported_perf_cap;

		break;

	case MSR_PLATFORM_INFO:

		*data = MSR_PLATFORM_INFO_CPUID_FAULT;

		break;

	case MSR_IA32_UCODE_REV:

		rdmsrl_safe(index, data);

		break;