Re: [PATCH v2 3/4] perf/x86/intel: Make @data a mandatory param for intel_guest_get_msrs()

Mi, Dapeng
2026-04-27T02:28:52Z

On 4/23/2026 11:03 PM, Sean Christopherson wrote:
> Drop "support" for passing a NULL @data/@kvm_pmu param when getting guest
> MSRs. KVM, the only in-tree user, unconditionally passes a non-NULL
> pointer, and carrying code that suggests @data may be NULL is confusing,
> e.g. incorrectly implies that there are scenarios where KVM doesn't pass
> a PMU context.
>
> Fixes: 8183a538cd95 ("KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to support guest DS")
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Mingwei Zhang <mizhang@google.com>
> Cc: Stephane Eranian <eranian@google.com>
> Reviewed-by: Jim Mattson <jmattson@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/events/intel/core.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index 407fd392fd46..7403ca721b6a 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -5038,11 +5038,11 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr, void *data)
> }
>
> /*
> - * If the guest won't use PEBS or the CPU doesn't support PEBS in the
> - * guest, then there's nothing more to do as disabling PMCs via
> - * PERF_GLOBAL_CTRL is sufficient on CPUs with guest/host isolation.
> + * If the CPU doesn't support PEBS in the guest, then there's nothing
> + * more to do as disabling PMCs via PERF_GLOBAL_CTRL is sufficient on
> + * CPUs with guest/host isolation.
> */
> - if (!kvm_pmu || !x86_pmu.pebs_ept)
> + if (!x86_pmu.pebs_ept)
> return arr;
>
> /*

LGTM. Thanks.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>