x86/kvm/hyper-v: add reenlightenment MSRs support

Nested Hyper-V/Windows guest running on top of KVM will use TSC page
clocksource in two cases:
- L0 exposes invariant TSC (CPUID.80000007H:EDX[8]).
- L0 provides Hyper-V Reenlightenment support (CPUID.40000003H:EAX[13]).

Exposing invariant TSC effectively blocks migration to hosts with different
TSC frequencies, providing reenlightenment support will be needed when we
start migrating nested workloads.

Implement rudimentary support for reenlightenment MSRs. For now, these are
just read/write MSRs with no effect.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index df6720fc57e6acc3cef50128a2563c673cc5d7c1..0395c354a50409873c6e8c0c21a4b8c96ec9825f 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -756,6 +756,10 @@ struct kvm_hv {
        HV_REFERENCE_TSC_PAGE tsc_ref;
 
        struct idr conn_to_evt;
+
+       u64 hv_reenlightenment_control;
+       u64 hv_tsc_emulation_control;
+       u64 hv_tsc_emulation_status;
 };
 
 enum kvm_irqchip_mode {

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 53bd1913b6fd0c33611e8d76133a502079813bab..2cffb94565f607947933d2b21008ca38609d387f 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -737,6 +737,9 @@ static bool kvm_hv_msr_partition_wide(u32 msr)
        case HV_X64_MSR_CRASH_CTL:
        case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
        case HV_X64_MSR_RESET:
+       case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
+       case HV_X64_MSR_TSC_EMULATION_CONTROL:
+       case HV_X64_MSR_TSC_EMULATION_STATUS:
                r = true;
                break;
        }
@@ -982,6 +985,15 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
                        kvm_make_request(KVM_REQ_HV_RESET, vcpu);
                }
                break;
+       case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
+               hv->hv_reenlightenment_control = data;
+               break;
+       case HV_X64_MSR_TSC_EMULATION_CONTROL:
+               hv->hv_tsc_emulation_control = data;
+               break;
+       case HV_X64_MSR_TSC_EMULATION_STATUS:
+               hv->hv_tsc_emulation_status = data;
+               break;
        default:
                vcpu_unimpl(vcpu, "Hyper-V uhandled wrmsr: 0x%x data 0x%llx\n",
                            msr, data);
@@ -1106,6 +1118,15 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
        case HV_X64_MSR_RESET:
                data = 0;
                break;
+       case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
+               data = hv->hv_reenlightenment_control;
+               break;
+       case HV_X64_MSR_TSC_EMULATION_CONTROL:
+               data = hv->hv_tsc_emulation_control;
+               break;
+       case HV_X64_MSR_TSC_EMULATION_STATUS:
+               data = hv->hv_tsc_emulation_status;
+               break;
        default:
                vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
                return 1;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6c81df94cd77c51b91557091bbc7ad169665c55b..36ef3d8aad18dec85f7db33cdfc40238386f5330 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1034,7 +1034,11 @@ static u32 emulated_msrs[] = {
        HV_X64_MSR_VP_RUNTIME,
        HV_X64_MSR_SCONTROL,
        HV_X64_MSR_STIMER0_CONFIG,
-       HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME,
+       HV_X64_MSR_APIC_ASSIST_PAGE,
+       HV_X64_MSR_REENLIGHTENMENT_CONTROL, HV_X64_MSR_TSC_EMULATION_CONTROL,
+       HV_X64_MSR_TSC_EMULATION_STATUS,
+
+       MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME,
        MSR_KVM_PV_EOI_EN,
 
        MSR_IA32_TSC_ADJUST,
@@ -2453,6 +2457,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
        case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
        case HV_X64_MSR_CRASH_CTL:
        case HV_X64_MSR_STIMER0_CONFIG ... HV_X64_MSR_STIMER3_COUNT:
+       case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
+       case HV_X64_MSR_TSC_EMULATION_CONTROL:
+       case HV_X64_MSR_TSC_EMULATION_STATUS:
                return kvm_hv_set_msr_common(vcpu, msr, data,
                                             msr_info->host_initiated);
        case MSR_IA32_BBL_CR_CTL3:
@@ -2683,6 +2690,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
        case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
        case HV_X64_MSR_CRASH_CTL:
        case HV_X64_MSR_STIMER0_CONFIG ... HV_X64_MSR_STIMER3_COUNT:
+       case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
+       case HV_X64_MSR_TSC_EMULATION_CONTROL:
+       case HV_X64_MSR_TSC_EMULATION_STATUS:
                return kvm_hv_get_msr_common(vcpu,
                                             msr_info->index, &msr_info->data);
                break;