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Thu, 13 Aug 2026 09:45:58 +0000 (GMT) Received: from localhost.localdomain (unknown [9.39.17.189]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 13 Aug 2026 09:45:58 +0000 (GMT) From: Gautam Menghani To: maddy@linux.ibm.com, atrajeev@linux.ibm.com, npiggin@gmail.com, mpe@ellerman.id.au, chleroy@kernel.org Cc: Gautam Menghani , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v2 3/3] powerpc/perf: Update prev_count of event to get accurate values Date: Thu, 13 Aug 2026 15:15:32 +0530 Message-ID: <20260813094535.10083-4-gautam@linux.ibm.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260813094535.10083-1-gautam@linux.ibm.com> References: <20260813094535.10083-1-gautam@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=XqfK/1F9 c=1 sm=1 tr=0 ts=6a7d925e cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=TypYd02-Uuc7vCoQRyAA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEzMDA2NiBTYWx0ZWRfXxqgqB3ZG1qdZ ErUrA78il1ezEKwjEyKfEnrnEL1onvtAhgHepV/K1iweCChlYGucWDugafzg/MxBncm4BMj5VJb SyafdIMrrsUJrULym08yy9hWwoxVsq4ecd4+kFtObOl4zRPrOUNZN9EEkRdhpJSW0cHcsizS+Sl 8+ZeMey0V/kP2flnO2tHqDTFxTMHWCoFlB8h/9f11gC8CER9ja60e4aWaJJ1KByB41L+gLfA4X0 yHSys88VqOhEhwqQg9HTQoYJQ35XkhCT30rHPndMtRRWggLaTsLmckwQgePVFG0VsxcssuEXKAx 0HOHBtare8eV4LrzWcZnKljnlmeyYgyEp+MVFa6qWUByj9/9KJEA7bZ5qk1WveySHQwGHDSTtPw H8/Svp0s8mkMWoE4AexWsdUTo9UeQh2IWIzIgcv8YpsKW3zC2rKGq8PnvjtRd+YzH5MluNA0yLz Z/5FD8ezJOkiZegRrNw== X-Proofpoint-ORIG-GUID: fJzjQxyJDKc7CjMXQGkzUAvl8JDkbBIh X-Proofpoint-GUID: ZVuaM1SgJm079P5i5UolAZq-6w_X2svt X-Proofpoint-Spam-Info: AW1haW4tMjYwODEzMDA2NiBTYWx0ZWRfX8kxVhX0VcfAA FcCrcTULJwm9eaWMvOv4674VZaU3Gxl9cIwzkvEg7pMw0w1mF/Asmqk1V9If9V86aKzNPseQaui 1KzqcJRsSFSfkintLuQf1UP7t1F11vM= 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=2026-08-13_03,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 spamscore=0 adultscore=0 malwarescore=0 clxscore=1015 suspectscore=0 priorityscore=1501 impostorscore=0 phishscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608130066 When vpa_pmu_read() is called twice while a process is running on a cpu, the "event->hw.prev_count" variable returns a stale value on the 2nd read which results in a larger value getting added to event->count. Fix this by updating the event->hw.prev_count every time vpa_pmu_read() is called. Fixes: 176cda0619b6 ("powerpc/perf: Add perf interface to expose vpa counters") Cc: Signed-off-by: Gautam Menghani --- v1 -> v2: 1. Add stable/fixes tags. arch/powerpc/perf/vpa-pmu.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/perf/vpa-pmu.c b/arch/powerpc/perf/vpa-pmu.c index e79d98447c74..efc39f71553b 100644 --- a/arch/powerpc/perf/vpa-pmu.c +++ b/arch/powerpc/perf/vpa-pmu.c @@ -156,6 +156,7 @@ static void vpa_pmu_read(struct perf_event *event) final_data = new_data - prev_data; local64_add(final_data, &event->count); + local64_set(&event->hw.prev_count, new_data); } static void vpa_pmu_del(struct perf_event *event, int flags) -- 2.54.0