linux-kernel - [PATCH 1/2] perf/x86/amd/uncore: Do not set ThreadMask and SliceMask for non-L3 PMCs

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Date:   Mon, 20 May 2019 22:00:12 +0000
From:   "Phillips, Kim" <kim.phillips@....com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "Phillips, Kim" <kim.phillips@....com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Martin Liška <mliska@...e.cz>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>,
        "Natarajan, Janakarajan" <Janakarajan.Natarajan@....com>,
        "Hook, Gary" <Gary.Hook@....com>, Pu Wen <puwen@...on.cn>,
        Stephane Eranian <eranian@...gle.com>,
        Vince Weaver <vincent.weaver@...ne.edu>,
        "x86@...nel.org" <x86@...nel.org>
Subject: [PATCH 1/2] perf/x86/amd/uncore: Do not set ThreadMask and SliceMask
 for non-L3 PMCs

From: Kim Phillips <kim.phillips@....com>

Commit d7cbbe49a930 ("perf/x86/amd/uncore: Set ThreadMask and SliceMask
for L3 Cache perf events") enables L3 PMC events for all threads and
slices by writing 1s in ChL3PmcCfg (L3 PMC PERF_CTL) register fields.

Those bitfields overlap with high order event select bits in the Data
Fabric PMC control register, however.

So when a user requests raw Data Fabric events (-e amd_df/event=0xYYY/),
the two highest order bits get inadvertently set, changing the counter
select to events that don't exist, and for which no counts are read.

This patch changes the logic to write the L3 masks only when dealing
with L3 PMC counters.

AMD Family 16h and below Northbridge (NB) counters were not affected.

Signed-off-by: Kim Phillips <kim.phillips@....com>
Cc: <stable@...r.kernel.org> # v4.19+
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Martin Liška <mliska@...e.cz>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
Cc: Janakarajan Natarajan <Janakarajan.Natarajan@....com>
Cc: Gary Hook <Gary.Hook@....com>
Cc: Pu Wen <puwen@...on.cn>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Cc: x86@...nel.org
Fixes: d7cbbe49a930 ("perf/x86/amd/uncore: Set ThreadMask and SliceMask for L3 Cache perf events")
---
 arch/x86/events/amd/uncore.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index 79cfd3b30ceb..a8dc2635a719 100644
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -209,7 +209,7 @@ static int amd_uncore_event_init(struct perf_event *event)
 	 * SliceMask and ThreadMask need to be set for certain L3 events in
 	 * Family 17h. For other events, the two fields do not affect the count.
 	 */
-	if (l3_mask)
+	if (l3_mask && is_llc_event(event))
 		hwc->config |= (AMD64_L3_SLICE_MASK | AMD64_L3_THREAD_MASK);
 
 	if (event->cpu < 0)
-- 
2.21.0