linux-kernel - Re: [PATCH v2 1/7] perf/x86/core: Update x86_pmu.pebs_capable for ICELAKE

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Date:   Mon, 15 Aug 2022 11:31:11 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Like Xu <like.xu.linux@...il.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [PATCH v2 1/7] perf/x86/core: Update x86_pmu.pebs_capable for
 ICELAKE_{X,D}

On Fri, Aug 12, 2022 at 09:52:13AM +0200, Paolo Bonzini wrote:
> On 7/21/22 12:35, Like Xu wrote:
> > From: Like Xu <likexu@...cent.com>
> > 
> > Ice Lake microarchitecture with EPT-Friendly PEBS capability also support
> > the Extended feature, which means that all counters (both fixed function
> > and general purpose counters) can be used for PEBS events.
> > 
> > Update x86_pmu.pebs_capable like SPR to apply PEBS_ALL semantics.
> > 
> > Cc: Kan Liang <kan.liang@...ux.intel.com>
> > Fixes: fb358e0b811e ("perf/x86/intel: Add EPT-Friendly PEBS for Ice Lake Server")
> > Signed-off-by: Like Xu <likexu@...cent.com>
> > ---
> >   arch/x86/events/intel/core.c | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> > index 4e9b7af9cc45..e46fd496187b 100644
> > --- a/arch/x86/events/intel/core.c
> > +++ b/arch/x86/events/intel/core.c
> > @@ -6239,6 +6239,7 @@ __init int intel_pmu_init(void)
> >   	case INTEL_FAM6_ICELAKE_X:
> >   	case INTEL_FAM6_ICELAKE_D:
> >   		x86_pmu.pebs_ept = 1;
> > +		x86_pmu.pebs_capable = ~0ULL;
> >   		pmem = true;
> >   		fallthrough;
> >   	case INTEL_FAM6_ICELAKE_L:
> 
> Peter, can you please ack this (you were not CCed on this KVM series but
> this patch is really perf core)?

I would much rather see something like this; except I don't know if it
is fully correct. I can never find what models support what... Kan do
you know?


diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 2db93498ff71..b42c1beb9924 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -5933,7 +5933,6 @@ __init int intel_pmu_init(void)
 		x86_pmu.pebs_aliases = NULL;
 		x86_pmu.pebs_prec_dist = true;
 		x86_pmu.lbr_pt_coexist = true;
-		x86_pmu.pebs_capable = ~0ULL;
 		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
 		x86_pmu.flags |= PMU_FL_PEBS_ALL;
 		x86_pmu.get_event_constraints = glp_get_event_constraints;
@@ -6291,7 +6290,6 @@ __init int intel_pmu_init(void)
 		x86_pmu.pebs_aliases = NULL;
 		x86_pmu.pebs_prec_dist = true;
 		x86_pmu.pebs_block = true;
-		x86_pmu.pebs_capable = ~0ULL;
 		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
 		x86_pmu.flags |= PMU_FL_NO_HT_SHARING;
 		x86_pmu.flags |= PMU_FL_PEBS_ALL;
@@ -6337,7 +6335,6 @@ __init int intel_pmu_init(void)
 		x86_pmu.pebs_aliases = NULL;
 		x86_pmu.pebs_prec_dist = true;
 		x86_pmu.pebs_block = true;
-		x86_pmu.pebs_capable = ~0ULL;
 		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
 		x86_pmu.flags |= PMU_FL_NO_HT_SHARING;
 		x86_pmu.flags |= PMU_FL_PEBS_ALL;
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index ba60427caa6d..e2da643632b9 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -2258,6 +2258,7 @@ void __init intel_ds_init(void)
 			x86_pmu.drain_pebs = intel_pmu_drain_pebs_icl;
 			x86_pmu.pebs_record_size = sizeof(struct pebs_basic);
 			if (x86_pmu.intel_cap.pebs_baseline) {
+				x86_pmu.pebs_capable = ~0ULL;
 				x86_pmu.large_pebs_flags |=
 					PERF_SAMPLE_BRANCH_STACK |
 					PERF_SAMPLE_TIME;