Commit d72bc7f6 authored by Ladi Prosek's avatar Ladi Prosek Committed by Paolo Bonzini
Browse files

i386/kvm: advertise Hyper-V frequency MSRs 



As of kernel commit eb82feea59d6 ("KVM: hyperv: support HV_X64_MSR_TSC_FREQUENCY
and HV_X64_MSR_APIC_FREQUENCY"), KVM supports two new MSRs which are required
for nested Hyper-V to read timestamps with RDTSC + TSC page.

This commit makes QEMU advertise the MSRs with CPUID.40000003H:EAX[11] and
CPUID.40000003H:EDX[8] as specified in the Hyper-V TLFS and experimentally
verified on a Hyper-V host. The feature is enabled with the existing hv-time CPU
flag, and only if the TSC frequency is stable across migrations and known.

Signed-off-by: default avatarLadi Prosek <lprosek@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Message-Id: <20170807085703.32267-5-lprosek@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4bb95b82

target/i386/kvm.c

+11 −1
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ static bool has_msr_hv_vpindex; 
static bool has_msr_hv_runtime;

static bool has_msr_hv_synic;

static bool has_msr_hv_stimer;

static bool has_msr_hv_frequencies;

static bool has_msr_xss;



static bool has_msr_architectural_pmu;
@@ -640,7 +641,13 @@ static int hyperv_handle_properties(CPUState *cs) 
    if (cpu->hyperv_time) {

        env->features[FEAT_HYPERV_EAX] |= HV_X64_MSR_HYPERCALL_AVAILABLE;

        env->features[FEAT_HYPERV_EAX] |= HV_X64_MSR_TIME_REF_COUNT_AVAILABLE;

        env->features[FEAT_HYPERV_EAX] |= 0x200;

        env->features[FEAT_HYPERV_EAX] |= HV_X64_MSR_REFERENCE_TSC_AVAILABLE;



        if (has_msr_hv_frequencies && tsc_is_stable_and_known(env)) {

            env->features[FEAT_HYPERV_EAX] |= HV_X64_ACCESS_FREQUENCY_MSRS;

            env->features[FEAT_HYPERV_EDX] |=

                HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;

        }

    }

    if (cpu->hyperv_crash && has_msr_hv_crash) {

        env->features[FEAT_HYPERV_EDX] |= HV_X64_GUEST_CRASH_MSR_AVAILABLE;
@@ -1134,6 +1141,9 @@ static int kvm_get_supported_msrs(KVMState *s) 
                case HV_X64_MSR_STIMER0_CONFIG:

                    has_msr_hv_stimer = true;

                    break;

                case HV_X64_MSR_TSC_FREQUENCY:

                    has_msr_hv_frequencies = true;

                    break;

                }

            }

        }