Commit be777326 authored by Wanpeng Li's avatar Wanpeng Li Committed by Eduardo Habkost
Browse files

target-i386: add KVM_HINTS_DEDICATED performance hint 



Add KVM_HINTS_DEDICATED performance hint, guest checks this feature bit
to determine if they run on dedicated vCPUs, allowing optimizations such
as usage of qspinlocks.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Message-Id: <1518185725-69559-1-git-send-email-wanpengli@tencent.com>
[ehabkost: Renamed property to kvm-hint-dedicated]
Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
parent b16a54da

target/i386/cpu.c

+14 −0
Original line number Diff line number Diff line
@@ -359,6 +359,20 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { 
        .cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EAX,

        .tcg_features = TCG_KVM_FEATURES,

    },

    [FEAT_KVM_HINTS] = {

        .feat_names = {

            "kvm-hint-dedicated", NULL, NULL, NULL,

            NULL, NULL, NULL, NULL,

            NULL, NULL, NULL, NULL,

            NULL, NULL, NULL, NULL,

            NULL, NULL, NULL, NULL,

            NULL, NULL, NULL, NULL,

            NULL, NULL, NULL, NULL,

            NULL, NULL, NULL, NULL,

        },

        .cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EDX,

        .tcg_features = TCG_KVM_FEATURES,

    },

    [FEAT_HYPERV_EAX] = {

        .feat_names = {

            NULL /* hv_msr_vp_runtime_access */, NULL /* hv_msr_time_refcount_access */,

target/i386/cpu.h

+3 −0
Original line number Diff line number Diff line
@@ -471,6 +471,7 @@ typedef enum FeatureWord { 
    FEAT_8000_0008_EBX, /* CPUID[8000_0008].EBX */

    FEAT_C000_0001_EDX, /* CPUID[C000_0001].EDX */

    FEAT_KVM,           /* CPUID[4000_0001].EAX (KVM_CPUID_FEATURES) */

    FEAT_KVM_HINTS,     /* CPUID[4000_0001].EDX */

    FEAT_HYPERV_EAX,    /* CPUID[4000_0003].EAX */

    FEAT_HYPERV_EBX,    /* CPUID[4000_0003].EBX */

    FEAT_HYPERV_EDX,    /* CPUID[4000_0003].EDX */
@@ -666,6 +667,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS]; 
#define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply Accumulation Single Precision */

#define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control */



#define KVM_HINTS_DEDICATED (1U << 0)



#define CPUID_8000_0008_EBX_IBPB    (1U << 12) /* Indirect Branch Prediction Barrier */



#define CPUID_XSAVE_XSAVEOPT   (1U << 0)

target/i386/kvm.c

+4 −0
Original line number Diff line number Diff line
@@ -383,6 +383,9 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, 
        if (!kvm_irqchip_in_kernel()) {

            ret &= ~(1U << KVM_FEATURE_PV_UNHALT);

        }

    } else if (function == KVM_CPUID_FEATURES && reg == R_EDX) {

        ret |= KVM_HINTS_DEDICATED;

        found = 1;

    }



    /* fallback for older kernels */
@@ -801,6 +804,7 @@ int kvm_arch_init_vcpu(CPUState *cs) 
        c = &cpuid_data.entries[cpuid_i++];

        c->function = KVM_CPUID_FEATURES | kvm_base;

        c->eax = env->features[FEAT_KVM];

        c->edx = env->features[FEAT_KVM_HINTS];

    }



    cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused);