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Thu, 13 Aug 2026 09:45:53 +0000 (GMT) Received: from localhost.localdomain (unknown [9.39.17.189]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 13 Aug 2026 09:45:52 +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 2/3] powerpc/perf: Use the aggregate context switch values from vcpu struct Date: Thu, 13 Aug 2026 15:15:31 +0530 Message-ID: <20260813094535.10083-3-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=RsP16imK c=1 sm=1 tr=0 ts=6a7d9258 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=-rbrNTDI_eUuE96cYmgA:9 X-Proofpoint-GUID: yb0obA1nLaqbo7Vd_URmiwfqML8o0VJ7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEzMDA2NiBTYWx0ZWRfX0an1HhXNGyMh PRrQ5jdAdoiSS2wJ1o+U+8dfztQCmrIV7ma1KqngNP7MsZa/alyipdhqLaIkRcBL3gwf+LfJaNK xHfWowHSQG/Jj4GN3VE6t95qMqj7imbUeyOT5QTOGbLoS7u+vdhvQbQix4+d9eOq1AF7X2lwBvP mOOg5Cz6R+4mB2I/19QCebgV+VThxoVtZTsxt78SxrlS1Udc+VKe70/5+KVQGzD/9o/0ZDewzpw MicQtx585KeoK8DyDEShbV2qir7GahlRIaJhM447vJKGFWLcPlROOeLXAraBFLH5/Z1Ri5lUU1G JI2Scl/R/nObHy3VBUK4G236zVY5DkozJNw4XqJgCaxqLngaoYgc8w1euyD5WAjfBUxKHQnzypz Q9kNkTDQNOMa3WGP8sg5BjS+TNZH1BLm4dxVSgOCxrA5yVEtVh9KEa38uLj4R0P05P21ZZs7RxE B4dt43GgF7vzjLXFpjg== X-Proofpoint-ORIG-GUID: dcShKy_oNPpG9IT38IU7AkxfXhehCRPN X-Proofpoint-Spam-Info: AW1haW4tMjYwODEzMDA2NiBTYWx0ZWRfX+2anfcH3TdjU 3UezvfBf0qHSSf6Dd2VGKFT55xnnYTWnKovEHJDksdp+s08JMfAJcluxji3C2Wa3c0XxmYJzouv BGY29bcb3RIfHxiPASAOjcZmpDPaSkU= 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 spamscore=0 impostorscore=0 suspectscore=0 clxscore=1015 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608130066 The vpa-pmu driver reports incorrect numbers in 2 scenarios: 1. The vCPU process gets rescheduled to a different host cpu - Incorrect numbers are observed here because the PACA is per-host cpu resource, and the KVM vCPUs can be rescheduled to different host cpus. This causes the vpa-pmu driver to subtract wrong values when vCPUs are rescheduled. 2. The vCPU is not running when vpa_pmu_read() is called. - In this case get_counter_data() returns 0, and this can result in negative numbers getting reported. Fix the above issues by using the aggregate values from the vcpu structure to capture and report the difference in counter values. Fixes: 176cda0619b6 ("powerpc/perf: Add perf interface to expose vpa counters") Cc: Signed-off-by: Gautam Menghani --- v1 -> v2: 1. Fix the output for "perf stat --cpu ..." 2. Add stable/fixes tags arch/powerpc/include/asm/kvm_book3s_64.h | 3 -- arch/powerpc/kvm/book3s_hv.c | 45 ------------------------ arch/powerpc/perf/vpa-pmu.c | 24 +++++++++---- 3 files changed, 18 insertions(+), 54 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h index b936e174eefd..f620e3126d68 100644 --- a/arch/powerpc/include/asm/kvm_book3s_64.h +++ b/arch/powerpc/include/asm/kvm_book3s_64.h @@ -691,9 +691,6 @@ void kvmhv_set_l2_counters_status(int cpu, bool status); u64 kvmhv_get_l1_to_l2_cs_time(void); u64 kvmhv_get_l2_to_l1_cs_time(void); u64 kvmhv_get_l2_runtime_agg(void); -u64 kvmhv_get_l1_to_l2_cs_time_vcpu(void); -u64 kvmhv_get_l2_to_l1_cs_time_vcpu(void); -u64 kvmhv_get_l2_runtime_agg_vcpu(void); #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 342168b8bfc8..b9285b7f1fed 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -4189,51 +4189,6 @@ u64 kvmhv_get_l2_runtime_agg(void) } EXPORT_SYMBOL(kvmhv_get_l2_runtime_agg); -u64 kvmhv_get_l1_to_l2_cs_time_vcpu(void) -{ - struct kvm_vcpu *vcpu; - struct kvm_vcpu_arch *arch; - - vcpu = local_paca->kvm_hstate.kvm_vcpu; - if (vcpu) { - arch = &vcpu->arch; - return arch->l1_to_l2_cs; - } else { - return 0; - } -} -EXPORT_SYMBOL(kvmhv_get_l1_to_l2_cs_time_vcpu); - -u64 kvmhv_get_l2_to_l1_cs_time_vcpu(void) -{ - struct kvm_vcpu *vcpu; - struct kvm_vcpu_arch *arch; - - vcpu = local_paca->kvm_hstate.kvm_vcpu; - if (vcpu) { - arch = &vcpu->arch; - return arch->l2_to_l1_cs; - } else { - return 0; - } -} -EXPORT_SYMBOL(kvmhv_get_l2_to_l1_cs_time_vcpu); - -u64 kvmhv_get_l2_runtime_agg_vcpu(void) -{ - struct kvm_vcpu *vcpu; - struct kvm_vcpu_arch *arch; - - vcpu = local_paca->kvm_hstate.kvm_vcpu; - if (vcpu) { - arch = &vcpu->arch; - return arch->l2_runtime_agg; - } else { - return 0; - } -} -EXPORT_SYMBOL(kvmhv_get_l2_runtime_agg_vcpu); - #else int kvmhv_get_l2_counters_status(void) { diff --git a/arch/powerpc/perf/vpa-pmu.c b/arch/powerpc/perf/vpa-pmu.c index bff4cfab7b94..e79d98447c74 100644 --- a/arch/powerpc/perf/vpa-pmu.c +++ b/arch/powerpc/perf/vpa-pmu.c @@ -91,7 +91,7 @@ static int vpa_pmu_event_init(struct perf_event *event) return 0; } -static unsigned long get_counter_data(struct perf_event *event) +static unsigned long get_counter_data(struct kvm_vcpu *vcpu, struct perf_event *event) { unsigned int config = event->attr.config; u64 data; @@ -99,19 +99,19 @@ static unsigned long get_counter_data(struct perf_event *event) switch (config) { case L1_TO_L2_CS_LAT: if (event->attach_state & PERF_ATTACH_TASK) - data = kvmhv_get_l1_to_l2_cs_time_vcpu(); + data = vcpu->arch.l1_to_l2_cs; else data = kvmhv_get_l1_to_l2_cs_time(); break; case L2_TO_L1_CS_LAT: if (event->attach_state & PERF_ATTACH_TASK) - data = kvmhv_get_l2_to_l1_cs_time_vcpu(); + data = vcpu->arch.l2_to_l1_cs; else data = kvmhv_get_l2_to_l1_cs_time(); break; case L2_RUNTIME_AGG: if (event->attach_state & PERF_ATTACH_TASK) - data = kvmhv_get_l2_runtime_agg_vcpu(); + data = vcpu->arch.l2_runtime_agg; else data = kvmhv_get_l2_runtime_agg(); break; @@ -126,21 +126,33 @@ static unsigned long get_counter_data(struct perf_event *event) static int vpa_pmu_add(struct perf_event *event, int flags) { u64 data; + struct kvm_vcpu *vcpu; + vcpu = local_paca->kvm_hstate.kvm_vcpu; + if (!vcpu) + goto out; + + event->pmu_private = vcpu; kvmhv_set_l2_counters_status(smp_processor_id(), true); - data = get_counter_data(event); + data = get_counter_data(vcpu, event); local64_set(&event->hw.prev_count, data); +out: return 0; } static void vpa_pmu_read(struct perf_event *event) { u64 prev_data, new_data, final_data; + struct kvm_vcpu *vcpu; + + vcpu = (struct kvm_vcpu *) event->pmu_private; + if (!vcpu) + return; prev_data = local64_read(&event->hw.prev_count); - new_data = get_counter_data(event); + new_data = get_counter_data(vcpu, event); final_data = new_data - prev_data; local64_add(final_data, &event->count); -- 2.54.0