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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: Wanpeng 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: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Wanpeng Li 2018-02-09 06:15:25 -08:00 committed by Eduardo Habkost
parent b16a54da06
commit be7773268d
3 changed files with 21 additions and 0 deletions
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14
target/i386/cpu.c
View File

@ -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 */,

3
target/i386/cpu.h
View File

@ -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)

4
target/i386/kvm.c
View File

@ -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);