Re: [PATCH v4 03/11] target/i386: disable PERFCORE when "-pmu" is configured

Sandipan Das
2025-04-25T10:12:00Z

On 4/17/2025 3:22 AM, Dongli Zhang wrote:
> Currently, AMD PMU support isn't determined based on CPUID, that is, the
> "-pmu" option does not fully disable KVM AMD PMU virtualization.
>
> To minimize AMD PMU features, remove PERFCORE when "-pmu" is configured.
>
> To completely disable AMD PMU virtualization will be implemented via
> KVM_CAP_PMU_CAPABILITY in upcoming patches.
>
> As a reminder, neither CPUID_EXT3_PERFCORE nor
> CPUID_8000_0022_EAX_PERFMON_V2 is removed from env->features[] when "-pmu"
> is configured. Developers should query whether they are supported via
> cpu_x86_cpuid() rather than relying on env->features[] in future patches.
>
> Suggested-by: Zhao Liu <zhao1.liu@intel.com>
> Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
> Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
> ---
> Changed since v2:
> - No need to check "kvm_enabled() && IS_AMD_CPU(env)".
>
> target/i386/cpu.c | 4 ++++
> 1 file changed, 4 insertions(+)
>

Reviewed-by: Sandipan Das <sandipan.das@amd.com>