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Wed, 19 Aug 2026 05:59:00 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 19 Aug 2026 05:59:00 +0000 (GMT) From: Thomas Richter To: linux-s390@vger.kernel.org Cc: Thomas Richter , Sumanth Korikkar , Heiko Carstens Subject: [PATCH v4] s390/pai: Handle multiple PMU stop callback invocations Date: Wed, 19 Aug 2026 07:58:55 +0200 Message-ID: <20260819055855.1001578-1-tmricht@linux.ibm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 8a_Oe4fjK02fRWAklUuv03ILd7SSDIJ3 X-Proofpoint-GUID: 8a_Oe4fjK02fRWAklUuv03ILd7SSDIJ3 X-Authority-Analysis: v=2.4 cv=RoX16imK c=1 sm=1 tr=0 ts=6a854629 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Fo9EMwYq_bmgDG0ZVhAA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwODE5MDAzOSBTYWx0ZWRfX2lclRYpaJGY9 JqLS0wz6Kqwfe5ejPaKxYxiBDI4ePuFkohH/NBFnzEgvv0xZRc4NK7CTnFmKTYc0QtQ3wW3n8pe A5D0a+2LHpeXi57m4TLkFv3/qox/S/U= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE5MDAzOSBTYWx0ZWRfX0qnVmnYy7mzf jugYSRaKwAzRcM5gbizSJq60IvgcZ0d+OKy8uM35Cdawk+rju1gfzT8ThmLvV4xxniIGfgXqqfe pExk9sW4dqwgUt1DJGCpOU58kXxb18MOENfJ6K1PnsYO+0THOIaued4hI+gkczTzzBMH1m9LYGw F3q8Luk/mnA7ZUakuGoTjpHTHTUatGzNn7cctJKrFdH+rr3AR587e9xEEt2KrcMn+2RdKofaKQX Xj0PmJC0y0z8Ez71cKt6GR1dsCsFDKfiaxaGa6AD6A555KBaP75Qb+XPcJc0cwqIbOaRHrRe9V0 euV4faBXhimaVDeiluObWipYyADU771KnD64ELMWSTbybw/W1RYrXpQXD1WKr1eMCrpiQZwtuAE /GUWfllwzZ4hTMiD2ckr6lvLenLB6fE4ZcIljETDiibBvIMzsmk0lRT7wCjhoJrrmyqWrckD1gQ eP8J9mqeW5f8Zh8pJng== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-19_01,2026-08-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 suspectscore=0 malwarescore=0 adultscore=0 clxscore=1015 phishscore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608190039 Handle the following scenario: The kernel protects itself against a very high sampling load and throttles the sampling using: perf_event_throttle() --> PMU->stop() Shortly later the scheduler may terminate the task and removes it from the CPU. It again calls PMU->stop() which results in two invocations of PMU->stop() called back to back. Protect against this and check the PERF_HES_STOPPED bit on function entry. If it is already set return. Clear bit PERF_HES_STOPPED in PMU->start(). Prohibit ioctl(fd, PERF_EVENT_IOC_PERIOD, ...) call for this event. It sets perf_event::event_limit to a positive value and causes perf_event_overflow() to invoke pai_stop() call back function when perf_event::event_limit hits zero. This is not supported because the sample events CRYPTO_ALL and NNPA_ALL are only taken at schedule out of a task. Use list_for_each_entry_safe() for safe iteration over syswide_list in pai_have_samples(). #Cc: stable@vger.kernel.org # v6.19+ Fixes: 9f66572f2889 ("s390/pai_crypto: Enable per-task and system-wide sampling event") Fixes: 582cc1b28e8c ("s390/pai_ext: Enable per-task and system-wide sampling event") Signed-off-by: Thomas Richter Reviewed-by: Sumanth Korikkar Suggested-by: Heiko Carstens --- arch/s390/kernel/perf_pai.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/arch/s390/kernel/perf_pai.c b/arch/s390/kernel/perf_pai.c index cdb8006220ca..05f74d74fad1 100644 --- a/arch/s390/kernel/perf_pai.c +++ b/arch/s390/kernel/perf_pai.c @@ -464,6 +464,7 @@ static void pai_start(struct perf_event *event, int flags, cpump->event = event; } } + event->hw.state &= ~PERF_HES_STOPPED; } static void paicrypt_start(struct perf_event *event, int flags) @@ -510,6 +511,13 @@ static void pai_stop(struct perf_event *event, int flags) struct pai_mapptr *mp = this_cpu_ptr(pai_root[idx].mapptr); struct pai_map *cpump = mp->mapptr; + /* Cope with multiple invocations: + * 1. perf_event_throttle() --> PMU->stop() + * 2. task schedules out --> PMU->stop() + * Check for event already stopped. + */ + if (event->hw.state & PERF_HES_STOPPED) + return; if (!event->attr.sample_period) { /* Counting */ pai_pmu[idx].pmu->read(event); } else { /* Sampling */ @@ -672,9 +680,9 @@ static void pai_have_samples(int idx) { struct pai_mapptr *mp = this_cpu_ptr(pai_root[idx].mapptr); struct pai_map *cpump = mp->mapptr; - struct perf_event *event; + struct perf_event *event, *e2; - list_for_each_entry(event, &cpump->syswide_list, hw.tp_list) + list_for_each_entry_safe(event, e2, &cpump->syswide_list, hw.tp_list) pai_have_sample(event, cpump); } @@ -691,6 +699,17 @@ static void paicrypt_sched_task(struct perf_event_pmu_context *pmu_ctx, pai_have_samples(PAI_PMU_CRYPTO); } +/* Prevent ioctl(fd, PERF_EVENT_IOC_PERIOD, ...) call. + * It sets perf_event::event_limit to a positive value and causes + * perf_event_overflow() to invoke pai_stop() call back function when + * perf_event::event_limit hits zero. This is not supported because the + * sample events CRYPTO_ALL and NNPA_ALL are always taken at schedule out + * of a task. + */ +static int pai_check_period(struct perf_event *event, u64 value) +{ + return -EINVAL; +} /* ============================= paiext ====================================*/ static void paiext_event_destroy(struct perf_event *event) @@ -804,6 +823,7 @@ static struct pmu paicrypt = { .stop = paicrypt_stop, .read = paicrypt_read, .sched_task = paicrypt_sched_task, + .check_period = pai_check_period, .attr_groups = paicrypt_attr_groups }; @@ -1015,6 +1035,7 @@ static struct pmu paiext = { .stop = paiext_stop, .read = paiext_read, .sched_task = paiext_sched_task, + .check_period = pai_check_period, .attr_groups = paiext_attr_groups, }; -- 2.55.0