[PATCH RFC 12/22] KVM: x86: hyper-v: Honor HV_ACCESS_FREQUENCY_MSRS privilege bit

[Vitaly Kuznetsov]

HV_X64_MSR_TSC_FREQUENCY/HV_X64_MSR_APIC_FREQUENCY are only available to
guest when HV_ACCESS_FREQUENCY_MSRS bit is exposed.

Note, writing to HV_X64_MSR_TSC_FREQUENCY/HV_X64_MSR_APIC_FREQUENCY is
unsupported so kvm_hv_set_msr() doesn't need an additional check.

Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
---
 arch/x86/kvm/hyperv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 9c4454873e00..e92a1109ad9b 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1637,9 +1637,17 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 
msr, u64 *pdata,
                                        pdata, host);
        }
        case HV_X64_MSR_TSC_FREQUENCY:
+               if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+                                       HV_ACCESS_FREQUENCY_MSRS)))
+                       return 1;
+
                data = (u64)vcpu->arch.virtual_tsc_khz * 1000;
                break;
        case HV_X64_MSR_APIC_FREQUENCY:
+               if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+                                       HV_ACCESS_FREQUENCY_MSRS)))
+                       return 1;
+
                data = APIC_BUS_FREQUENCY;
                break;
        default:
-- 
2.30.2