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From: Ravi Bangoria <ravi.bangoria@amd.com>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Dapeng Mi <dapeng1.mi@linux.intel.com>,
	James Clark <james.clark@linaro.org>, <x86@kernel.org>,
	<linux-perf-users@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	"Manali Shukla" <manali.shukla@amd.com>,
	Santosh Shukla <santosh.shukla@amd.com>,
	Ananth Narayan <ananth.narayan@amd.com>,
	Sandipan Das <sandipan.das@amd.com>
Subject: [PATCH 02/11] perf/amd/ibs: Limit ldlat->l3missonly dependency to Zen5
Date: Fri, 16 Jan 2026 03:34:41 +0000	[thread overview]
Message-ID: <20260116033450.965-3-ravi.bangoria@amd.com> (raw)
In-Reply-To: <20260116033450.965-1-ravi.bangoria@amd.com>

The ldlat dependency on l3missonly is specific to Zen 5; newer generations
are not affected. This quirk is documented as an erratum in the following
Revision Guide.

  Erratum: 1606 IBS (Instruction Based Sampling) OP Load Latency Filtering
           May Capture Unwanted Samples When L3Miss Filtering is Disabled

  Revision Guide for AMD Family 1Ah Models 00h-0Fh Processors,
  Pub. 58251 Rev. 1.30 July 2025
  https://bugzilla.kernel.org/attachment.cgi?id=309193

Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
---
 arch/x86/events/amd/ibs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 96bb0974057f..dc8cc173cdf5 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -356,7 +356,10 @@ static int perf_ibs_init(struct perf_event *event)
 		ldlat >>= 7;
 
 		config |= (ldlat - 1) << 59;
-		config |= IBS_OP_L3MISSONLY | IBS_OP_LDLAT_EN;
+
+		config |= IBS_OP_LDLAT_EN;
+		if (cpu_feature_enabled(X86_FEATURE_ZEN5))
+			config |= IBS_OP_L3MISSONLY;
 	}
 
 	/*
-- 
2.43.0


  parent reply	other threads:[~2026-01-16  3:35 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-01-16  3:34 [PATCH 00/11] perf/amd/ibs: Fixes + future enhancements Ravi Bangoria
2026-01-16  3:34 ` [PATCH 01/11] perf/amd/ibs: Throttle interrupts with filtered ldlat samples Ravi Bangoria
2026-01-19  7:31   ` Mi, Dapeng
2026-01-19 12:56     ` Ravi Bangoria
2026-01-16  3:34 ` Ravi Bangoria [this message]
2026-01-16  3:34 ` [PATCH 03/11] perf/amd/ibs: Preserve PhyAddrVal bit when clearing PhyAddr MSR Ravi Bangoria
2026-01-16  3:34 ` [PATCH 04/11] perf/amd/ibs: Avoid race between event add and NMI Ravi Bangoria
2026-01-16  3:34 ` [PATCH 05/11] perf/amd/ibs: Define macro for ldlat mask Ravi Bangoria
2026-01-19  7:38   ` Mi, Dapeng
2026-01-16  3:34 ` [PATCH 06/11] perf/amd/ibs: Add new MSRs and CPUID bits definitions Ravi Bangoria
2026-01-19  7:39   ` Mi, Dapeng
2026-01-16  3:34 ` [PATCH 07/11] perf/amd/ibs: Support IBS_{FETCH|OP}_CTL2[Dis] to eliminate RMW race Ravi Bangoria
2026-01-19  7:48   ` Mi, Dapeng
2026-01-19 13:00     ` Ravi Bangoria
2026-01-16  3:34 ` [PATCH 08/11] perf/amd/ibs: Enable fetch latency filtering Ravi Bangoria
2026-01-16  3:34 ` [PATCH 09/11] perf/amd/ibs: Enable RIP bit63 hardware filtering Ravi Bangoria
2026-01-16  3:34 ` [PATCH 10/11] perf/amd/ibs: Enable streaming store filter Ravi Bangoria
2026-01-19  7:57   ` Mi, Dapeng
2026-01-19 13:02     ` Ravi Bangoria
2026-01-16  3:34 ` [PATCH 11/11] perf/amd/ibs: Advertise remote socket capability Ravi Bangoria

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