diff --git a/docs/hyperv.txt b/docs/hyperv.txt index 33588a0396..5d85569b99 100644 --- a/docs/hyperv.txt +++ b/docs/hyperv.txt @@ -239,6 +239,15 @@ This enlightenment requires a VMBus device (-device vmbus-bridge,irq=15) and the follow enlightenments to work: hv-relaxed,hv_time,hv-vapic,hv-vpindex,hv-synic,hv-runtime,hv-stimer +3.22. hv-emsr-bitmap +===================== +The enlightenment is nested specific, it targets Hyper-V on KVM guests. When +enabled, it allows L0 (KVM) and L1 (Hyper-V) hypervisors to collaborate to +avoid unnecessary updates to L2 MSR-Bitmap upon vmexits. While the protocol is +supported for both VMX (Intel) and SVM (AMD), the VMX implementation requires +Enlightened VMCS ('hv-evmcs') feature to also be enabled. + +Recommended: hv-evmcs (Intel) 4. Supplementary features ========================= diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 385691458f..474e9b582e 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -6968,6 +6968,8 @@ static Property x86_cpu_properties[] = { HYPERV_FEAT_STIMER_DIRECT, 0), DEFINE_PROP_BIT64("hv-avic", X86CPU, hyperv_features, HYPERV_FEAT_AVIC, 0), + DEFINE_PROP_BIT64("hv-emsr-bitmap", X86CPU, hyperv_features, + HYPERV_FEAT_MSR_BITMAP, 0), DEFINE_PROP_ON_OFF_AUTO("hv-no-nonarch-coresharing", X86CPU, hyperv_no_nonarch_cs, ON_OFF_AUTO_OFF), DEFINE_PROP_BIT64("hv-syndbg", X86CPU, hyperv_features, diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 2e918daf6b..c788285736 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1106,6 +1106,7 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w, #define HYPERV_FEAT_STIMER_DIRECT 14 #define HYPERV_FEAT_AVIC 15 #define HYPERV_FEAT_SYNDBG 16 +#define HYPERV_FEAT_MSR_BITMAP 17 #ifndef HYPERV_SPINLOCK_NEVER_NOTIFY #define HYPERV_SPINLOCK_NEVER_NOTIFY 0xFFFFFFFF diff --git a/target/i386/kvm/hyperv-proto.h b/target/i386/kvm/hyperv-proto.h index e40e59411c..cea18dbc0e 100644 --- a/target/i386/kvm/hyperv-proto.h +++ b/target/i386/kvm/hyperv-proto.h @@ -86,6 +86,11 @@ */ #define HV_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING (1u << 1) +/* + * HV_CPUID_NESTED_FEATURES.EAX bits + */ +#define HV_NESTED_MSR_BITMAP (1u << 19) + /* * Basic virtualized MSRs */ diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 38af0e4f04..f389bbedf2 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -973,6 +973,13 @@ static struct { .dependencies = BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_RELAXED) }, #endif + [HYPERV_FEAT_MSR_BITMAP] = { + .desc = "enlightened MSR-Bitmap (hv-emsr-bitmap)", + .flags = { + {.func = HV_CPUID_NESTED_FEATURES, .reg = R_EAX, + .bits = HV_NESTED_MSR_BITMAP} + } + }, }; static struct kvm_cpuid2 *try_get_hv_cpuid(CPUState *cs, int max,