Hi Zhao,
On 6/13/24 02:06, Zhao Liu wrote:
> On Wed, Jun 12, 2024 at 02:12:18PM -0500, Babu Moger wrote:
>> Date: Wed, 12 Jun 2024 14:12:18 -0500
>> From: Babu Moger <babu.moger@xxxxxxx>
>> Subject: [PATCH 2/4] i386/cpu: Add PerfMonV2 feature bit
>> X-Mailer: git-send-email 2.34.1
>>
>> From: Sandipan Das <sandipan.das@xxxxxxx>
>>
>> CPUID leaf 0x80000022, i.e. ExtPerfMonAndDbg, advertises new performance
>> monitoring features for AMD processors. Bit 0 of EAX indicates support
>> for Performance Monitoring Version 2 (PerfMonV2) features. If found to
>> be set during PMU initialization, the EBX bits can be used to determine
>> the number of available counters for different PMUs. It also denotes the
>> availability of global control and status registers.
>>
>> Add the required CPUID feature word and feature bit to allow guests to
>> make use of the PerfMonV2 features.
>>
>> Signed-off-by: Sandipan Das <sandipan.das@xxxxxxx>
>> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
>> ---
>> target/i386/cpu.c | 26 ++++++++++++++++++++++++++
>> target/i386/cpu.h | 4 ++++
>> 2 files changed, 30 insertions(+)
>>
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index 86a90b1405..7f1837cdc9 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -1228,6 +1228,22 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>> .tcg_features = 0,
>> .unmigratable_flags = 0,
>> },
>> + [FEAT_8000_0022_EAX] = {
>> + .type = CPUID_FEATURE_WORD,
>> + .feat_names = {
>> + "perfmon-v2", 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 = 0x80000022, .reg = R_EAX, },
>> + .tcg_features = 0,
>> + .unmigratable_flags = 0,
>> + },
>> [FEAT_XSAVE] = {
>> .type = CPUID_FEATURE_WORD,
>> .feat_names = {
>> @@ -6998,6 +7014,16 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>> *edx = 0;
>> }
>> break;
>> + case 0x80000022:
>> + *eax = *ebx = *ecx = *edx = 0;
>> + /* AMD Extended Performance Monitoring and Debug */
>> + if (kvm_enabled() && cpu->enable_pmu &&
>> + (env->features[FEAT_8000_0022_EAX] & CPUID_8000_0022_EAX_PERFMON_V2)) {
>> + *eax = CPUID_8000_0022_EAX_PERFMON_V2;
>> + *ebx = kvm_arch_get_supported_cpuid(cs->kvm_state, index, count,
>> + R_EBX) & 0xf;
>
> Although only EAX[bit 0] and EBX[bits 0-3] are supported right now, I
> think it's better to use “|=” rather than just override the
> original *eax and *ebx, which will prevent future mistakes or omissions.
Sure. Will do. Thanks for the review.
>
> Otherwise,
>
> Reviewed-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
>
--
Thanks
Babu Moger
