Kernel KVM virtualization development
 help / color / mirror / Atom feed
From: "Mi, Dapeng" <dapeng1.mi@linux.intel.com>
To: Sean Christopherson <seanjc@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	James Clark <james.clark@linaro.org>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, Jim Mattson <jmattson@google.com>,
	Mingwei Zhang <mizhang@google.com>,
	Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH v3 8/9] KVM: VMX: Drop a redundant pmu->global_ctrl check when processing pebs_enable
Date: Tue, 12 May 2026 13:00:37 +0800	[thread overview]
Message-ID: <72b65be8-436d-4db8-97d9-6f4e628b7b47@linux.intel.com> (raw)
In-Reply-To: <20260508231353.406465-9-seanjc@google.com>


On 5/9/2026 7:13 AM, Sean Christopherson wrote:
> Drop a redundant check that a PMC is globally enabled when looking for
> PEBS counters that are cross-mapped between the guest and the host.  The
> for-loop explicitly iterates over pmu->global_ctrl, and since PEBS requires
> PMU v2+, kvm_pmu_has_perf_global_ctrl() must be true, and thus
> pmc_is_globally_enabled() is simply checking that the bit is set in
> pmu->global_ctrl.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>  arch/x86/kvm/vmx/pmu_intel.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
> index e65adb3dc066..659fe097b904 100644
> --- a/arch/x86/kvm/vmx/pmu_intel.c
> +++ b/arch/x86/kvm/vmx/pmu_intel.c
> @@ -752,8 +752,7 @@ u64 intel_pmu_get_cross_mapped_mask(struct kvm_pmu *pmu)
>  	host_cross_mapped_mask = 0;
>  
>  	kvm_for_each_pmc(pmu, pmc, bit, (unsigned long *)&pmu->global_ctrl) {
> -		if (!pmc_is_locally_enabled(pmc) ||
> -		    !pmc_is_globally_enabled(pmc) || !pmc->perf_event)
> +		if (!pmc_is_locally_enabled(pmc) || !pmc->perf_event)
>  			continue;
>  
>  		/*

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



  reply	other threads:[~2026-05-12  5:00 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-08 23:13 [PATCH v3 0/9] perf/x86: Don't write PEBS_ENABLED on KVM transitions Sean Christopherson
2026-05-08 23:13 ` [PATCH v3 1/9] perf/x86/intel: Ensure guest PEBS path doesn't set unwanted PERF_GLOBAL_CTRL bits Sean Christopherson
2026-05-12  4:53   ` Mi, Dapeng
2026-05-08 23:13 ` [PATCH v3 2/9] perf/x86/intel: Don't write PEBS_ENABLED on host<=>guest xfers if CPU has isolation Sean Christopherson
2026-05-12  4:53   ` Mi, Dapeng
2026-05-08 23:13 ` [PATCH v3 3/9] perf/x86/intel: Don't context switch DS_AREA (and PEBS config) if PEBS is unused Sean Christopherson
2026-05-08 23:13 ` [PATCH v3 4/9] perf/x86/intel: Make @data a mandatory param for intel_guest_get_msrs() Sean Christopherson
2026-05-12 12:39   ` Jim Mattson
2026-05-08 23:13 ` [PATCH v3 5/9] perf/x86/intel: Invert names of intel_ctrl_{guest,host}_mask Sean Christopherson
2026-05-12  4:58   ` Mi, Dapeng
2026-05-08 23:13 ` [PATCH v3 6/9] perf/x86: KVM: Have perf define a dedicated struct for getting guest PEBS data Sean Christopherson
2026-05-08 23:13 ` [PATCH v3 7/9] perf/x86/intel: KVM: Handle cross-mapped PEBS PMCs entirely within KVM Sean Christopherson
2026-05-12  4:59   ` Mi, Dapeng
2026-05-08 23:13 ` [PATCH v3 8/9] KVM: VMX: Drop a redundant pmu->global_ctrl check when processing pebs_enable Sean Christopherson
2026-05-12  5:00   ` Mi, Dapeng [this message]
2026-05-08 23:13 ` [PATCH v3 9/9] KVM: VMX: Only tell perf to enable PEBS counters for fully enabled PMCs Sean Christopherson
2026-05-12  5:01   ` Mi, Dapeng

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=72b65be8-436d-4db8-97d9-6f4e628b7b47@linux.intel.com \
    --to=dapeng1.mi@linux.intel.com \
    --cc=acme@kernel.org \
    --cc=adrian.hunter@intel.com \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=eranian@google.com \
    --cc=irogers@google.com \
    --cc=james.clark@linaro.org \
    --cc=jmattson@google.com \
    --cc=jolsa@kernel.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-perf-users@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mingo@redhat.com \
    --cc=mizhang@google.com \
    --cc=namhyung@kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=peterz@infradead.org \
    --cc=seanjc@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox