Re: [Qemu-devel] [PATCH] target-i386: adds PV_DEDICATED hint CPUID feature bit

[Wanpeng Li <kernellwp@gmail.com>]

2018-02-09 16:41 GMT+08:00 Paolo Bonzini <bonzini@gnu.org>:
> On 08/02/2018 10:44, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpengli@tencent.com>
>>
>> Add PV_DEDICATED hint cpuid feature bit.
>
> Please add a new feature word, since this is not a PV feature but more
> like a performance hint.

Do it in v2.

Regards,
Wanpeng Li

>
> Thanks,
>
> Paolo
>
>> 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>
>> ---
>>  target/i386/cpu.c | 4 ++++
>>  target/i386/cpu.h | 3 +++
>>  2 files changed, 7 insertions(+)
>>
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index d70954b..cf48931 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu)
>>              x86_cpu_get_supported_feature_word(w, false);
>>          uint32_t requested_features = env->features[w];
>>          env->features[w] &= host_feat;
>> +        if (cpu->pv_dedicated && (w == FEAT_KVM)) {
>> +            env->features[w] |= CPUID_PV_DEDICATED;
>> +        }
>>          cpu->filtered_features[w] = requested_features & ~env->features[w];
>>          if (cpu->filtered_features[w]) {
>>              rv = 1;
>> @@ -4682,6 +4685,7 @@ static Property x86_cpu_properties[] = {
>>                       false),
>>      DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true),
>>      DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true),
>> +    DEFINE_PROP_BOOL("pv-dedicated", X86CPU, pv_dedicated, false),
>>
>>      /*
>>       * From "Requirements for Implementing the Microsoft
>> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
>> index f91e37d..8000da5 100644
>> --- a/target/i386/cpu.h
>> +++ b/target/i386/cpu.h
>> @@ -672,6 +672,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
>>
>>  #define CPUID_8000_0008_EBX_IBPB    (1U << 12) /* Indirect Branch Prediction Barrier */
>>
>> +#define CPUID_PV_DEDICATED     (1U << 8)
>> +
>>  #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
>>  #define CPUID_XSAVE_XSAVEC     (1U << 1)
>>  #define CPUID_XSAVE_XGETBV1    (1U << 2)
>> @@ -1276,6 +1278,7 @@ struct X86CPU {
>>      bool expose_kvm;
>>      bool expose_tcg;
>>      bool migratable;
>> +    bool pv_dedicated;
>>      bool max_features; /* Enable all supported features automatically */
>>      uint32_t apic_id;
>>
>>
>