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Subject[PATCH 1/2 RESEND2] perf/x86/amd/uncore: Do not set ThreadMask and SliceMask for non-L3 PMCs
Date
From: Kim Phillips <kim.phillips@amd.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@amd.com>
Cc: <stable@vger.kernel.org> # v4.19+
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Martin Liska <mliska@suse.cz>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Cc: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Cc: Gary Hook <Gary.Hook@amd.com>
Cc: Pu Wen <puwen@hygon.cn>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: x86@kernel.org
Fixes: d7cbbe49a930 ("perf/x86/amd/uncore: Set ThreadMask and SliceMask for L3 Cache perf events")
---
RESEND: 3rd attempt, this time with --transfer-encoding=7bit to try to pass
Peter Z.'s scripts not liking base64 encoded emails.

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 85e6984c560b..c2c4ae5fbbfc 100644
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -206,7 +206,7 @@ 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)
--
2.22.0
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