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From: Gautam Menghani <gautam@linux.ibm.com>
To: maddy@linux.ibm.com, atrajeev@linux.ibm.com, npiggin@gmail.com,
	mpe@ellerman.id.au, chleroy@kernel.org
Cc: Gautam Menghani <gautam@linux.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 1/3] KVM: PPC: Book3S HV: Maintain aggregate context switch values for vCPUs
Date: Tue, 11 Aug 2026 19:33:07 +0530	[thread overview]
Message-ID: <20260811140313.15397-2-gautam@linux.ibm.com> (raw)
In-Reply-To: <20260811140313.15397-1-gautam@linux.ibm.com>

The variables in vcpu->arch currently store the latest values read from
PACA when the vCPU exits. Change this to instead store aggregate values
so that every vCPU has its own record of total context switch latencies
it has accumulated. This is essential for the vpa-pmu driver to report
correct numbers.

Signed-off-by: Gautam Menghani <gautam@linux.ibm.com>
---
 arch/powerpc/kvm/book3s_hv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 3cfe9a7be9c6..0e8a959122a8 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4164,12 +4164,12 @@ static void do_trace_nested_cs_time(struct kvm_vcpu *vcpu)
 	trace_kvmppc_vcpu_stats(vcpu, l1_to_l2_ns - *l1_to_l2_cs_ptr,
 					l2_to_l1_ns - *l2_to_l1_cs_ptr,
 					l2_runtime_ns - *l2_runtime_agg_ptr);
+	vcpu->arch.l1_to_l2_cs += (l1_to_l2_ns - *l1_to_l2_cs_ptr);
+	vcpu->arch.l2_to_l1_cs += (l2_to_l1_ns - *l2_to_l1_cs_ptr);
+	vcpu->arch.l2_runtime_agg += (l2_runtime_ns - *l2_runtime_agg_ptr);
 	*l1_to_l2_cs_ptr = l1_to_l2_ns;
 	*l2_to_l1_cs_ptr = l2_to_l1_ns;
 	*l2_runtime_agg_ptr = l2_runtime_ns;
-	vcpu->arch.l1_to_l2_cs = l1_to_l2_ns;
-	vcpu->arch.l2_to_l1_cs = l2_to_l1_ns;
-	vcpu->arch.l2_runtime_agg = l2_runtime_ns;
 }
 
 u64 kvmhv_get_l1_to_l2_cs_time(void)
-- 
2.54.0


  reply	other threads:[~2026-08-11 14:03 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-11 14:03 [PATCH 0/3] powerpc/perf: Fix vpa-pmu driver to report correct Gautam Menghani
2026-08-11 14:03 ` Gautam Menghani [this message]
2026-08-11 14:03 ` [PATCH 2/3] powerpc/perf: Use the aggregate context switch values from vcpu struct Gautam Menghani
2026-08-11 14:03 ` [PATCH 3/3] powerpc/perf: Update prev_count of event to get accurate values Gautam Menghani

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