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Tue, 11 Aug 2026 14:03:40 +0000 (GMT) Received: from localhost.localdomain (unknown [9.124.219.6]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 11 Aug 2026 14:03:40 +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 Subject: [PATCH 3/3] powerpc/perf: Update prev_count of event to get accurate values Date: Tue, 11 Aug 2026 19:33:09 +0530 Message-ID: <20260811140313.15397-4-gautam@linux.ibm.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260811140313.15397-1-gautam@linux.ibm.com> References: <20260811140313.15397-1-gautam@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@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-Proofpoint-GUID: u4Na4jzxmqRsBFgKisVgJDNiZERexDqA X-Authority-Analysis: v=2.4 cv=PbDPQChd c=1 sm=1 tr=0 ts=6a7b2bc4 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=2AWsWaKDJcEKxLcdIakA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODExMDExNyBTYWx0ZWRfX5VXTNq0FaKf8 Qysatjkipqj+OzTqOUeaHVRPTakkrv9q1p693Ntr8EIoaZ2Cyndj4mMwXbausru4ksnUcAYWkaY yxCiiUAlie/++h+VxfZ8hmXWdaFZzCqsFXB87TjVPpr5JCN5pkvA3pXkIOWUK7M+9mmLdIZtgqw 9YxANRKgNZC65QHFwJnXawGu0IFvgxhuH/d2EZUHNM5DCUMD9QhEeoz2Bicgd1PePMZ1g44ycHK zzSKbKxCr68TZCRwmKw7Fi5HlZEPbVjUr1Q09MbdOgCeeHEjh+rVKq/zbQq9FoX/Rd0zqrGdyuQ xj/XnKbrDlecmjYerkTiqCoNEpAqSeGdWp8JtbzOXrj1aI6yd34+aa1wNrYwAzhwh1Hpb+VEoh0 fKHIio2PXGJ3geINzIxgoBXz05YeWnpVcRinUbOZv5zZmaZTB4n+yEVOO26E+gb3sR1nKjsoX6K Pr6Ktr5Vj48836BSecg== X-Proofpoint-ORIG-GUID: pIdlkqF6E0zehb9GQMbNwchtfqSQ5FfX X-Proofpoint-Spam-Info: AW1haW4tMjYwODExMDExNyBTYWx0ZWRfXw3ycQyk6lPb0 smC+YbrhzeemXW+C0Ww5dmPd981VMHLC3HKID6iGE5lFcWMtN99hg+Nedkfu//8nCRQKNPoMVBh /1RFk5tDkh7XOquPjhqSFlyBt++z1zA= 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=2026-08-11_03,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 bulkscore=0 impostorscore=0 malwarescore=0 adultscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 phishscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608110117 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. Signed-off-by: Gautam Menghani --- 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 334ef7719db9..f5cfa4d5e369 100644 --- a/arch/powerpc/perf/vpa-pmu.c +++ b/arch/powerpc/perf/vpa-pmu.c @@ -145,6 +145,7 @@ 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