2018-03-09 22:16 GMT+08:00 Eduardo Habkost <ehabkost@xxxxxxxxxx>:
> On Fri, Feb 09, 2018 at 06:15:25AM -0800, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>>
>> 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@xxxxxxxxxx>
>> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
>> Cc: Eduardo Habkost <ehabkost@xxxxxxxxxx>
>> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>> ---
>> v1 -> v2:
>> * add a new feature word
>>
>> target/i386/cpu.c | 14 ++++++++++++++
>> target/i386/cpu.h | 3 +++
>> target/i386/kvm.c | 4 ++++
>> 3 files changed, 21 insertions(+)
>>
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index d70954b..e2974ad 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -358,6 +358,20 @@ 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 = {
>> + "hint-dedicated", NULL, NULL, NULL,
>
> I suggest naming it "kvm-hint-dedicated", to indicate it's
> KVM-specific.
>
> If there are no objections, I can rename it while applying.
Looks good to me, thanks Eduardo.
Regards,
Wanpeng Li
>
> With the rename:
>
> Reviewed-by: Eduardo Habkost <ehabkost@xxxxxxxxxx>
>
>
>> + 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 */,
>> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
>> index f91e37d..9f73692 100644
>> --- a/target/i386/cpu.h
>> +++ b/target/i386/cpu.h
>> @@ -475,6 +475,7 @@ 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 */
>> @@ -670,6 +671,8 @@ 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)
>> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
>> index ad4b159..44ee524 100644
>> --- a/target/i386/kvm.c
>> +++ b/target/i386/kvm.c
>> @@ -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);
>> --
>> 2.7.4
>>
>
> --
> Eduardo
