linux-kernel - [PATCH 4.14 82/99] perf/amd/uncore: Replace manual sampling check with CAP_NO

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Message-Id: <20200319124005.115184451@linuxfoundation.org>
Date:   Thu, 19 Mar 2020 14:04:00 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kim Phillips <kim.phillips@....com>,
        Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 82/99] perf/amd/uncore: Replace manual sampling check with CAP_NO_INTERRUPT flag

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

[ Upstream commit f967140dfb7442e2db0868b03b961f9c59418a1b ]

Enable the sampling check in kernel/events/core.c::perf_event_open(),
which returns the more appropriate -EOPNOTSUPP.

BEFORE:

  $ sudo perf record -a -e instructions,l3_request_g1.caching_l3_cache_accesses true
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (l3_request_g1.caching_l3_cache_accesses).
  /bin/dmesg | grep -i perf may provide additional information.

With nothing relevant in dmesg.

AFTER:

  $ sudo perf record -a -e instructions,l3_request_g1.caching_l3_cache_accesses true
  Error:
  l3_request_g1.caching_l3_cache_accesses: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'

Fixes: c43ca5091a37 ("perf/x86/amd: Add support for AMD NB and L2I "uncore" counters")
Signed-off-by: Kim Phillips <kim.phillips@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/20200311191323.13124-1-kim.phillips@amd.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/events/amd/uncore.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index baa7e36073f90..604a8558752d1 100644
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -193,20 +193,18 @@ static int amd_uncore_event_init(struct perf_event *event)
 
 	/*
 	 * NB and Last level cache counters (MSRs) are shared across all cores
-	 * that share the same NB / Last level cache. Interrupts can be directed
-	 * to a single target core, however, event counts generated by processes
-	 * running on other cores cannot be masked out. So we do not support
-	 * sampling and per-thread events.
+	 * that share the same NB / Last level cache.  On family 16h and below,
+	 * Interrupts can be directed to a single target core, however, event
+	 * counts generated by processes running on other cores cannot be masked
+	 * out. So we do not support sampling and per-thread events via
+	 * CAP_NO_INTERRUPT, and we do not enable counter overflow interrupts:
 	 */
-	if (is_sampling_event(event) || event->attach_state & PERF_ATTACH_TASK)
-		return -EINVAL;
 
 	/* NB and Last level cache counters do not have usr/os/guest/host bits */
 	if (event->attr.exclude_user || event->attr.exclude_kernel ||
 	    event->attr.exclude_host || event->attr.exclude_guest)
 		return -EINVAL;
 
-	/* and we do not enable counter overflow interrupts */
 	hwc->config = event->attr.config & AMD64_RAW_EVENT_MASK_NB;
 	hwc->idx = -1;
 
@@ -314,6 +312,7 @@ static struct pmu amd_nb_pmu = {
 	.start		= amd_uncore_start,
 	.stop		= amd_uncore_stop,
 	.read		= amd_uncore_read,
+	.capabilities	= PERF_PMU_CAP_NO_INTERRUPT,
 };
 
 static struct pmu amd_llc_pmu = {
@@ -324,6 +323,7 @@ static struct pmu amd_llc_pmu = {
 	.start		= amd_uncore_start,
 	.stop		= amd_uncore_stop,
 	.read		= amd_uncore_read,
+	.capabilities	= PERF_PMU_CAP_NO_INTERRUPT,
 };
 
 static struct amd_uncore *amd_uncore_alloc(unsigned int cpu)
-- 
2.20.1