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From: Atish Patra <atishp@rivosinc.com>
To: linux-kernel@vger.kernel.org
Cc: Atish Patra <atishp@rivosinc.com>,
	Anup Patel <anup@brainfault.org>,
	Andrew Jones <ajones@ventanamicro.com>,
	Ajay Kaher <ajay.kaher@broadcom.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alexghiti@rivosinc.com>,
	Alexey Makhalov <alexey.amakhalov@broadcom.com>,
	Atish Patra <atishp@atishpatra.org>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>,
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	Will Deacon <will@kernel.org>,
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Subject: [PATCH v6 11/24] RISC-V: KVM: No need to update the counter value during reset
Date: Wed, 10 Apr 2024 17:07:39 -0700
Message-Id: <20240411000752.955910-12-atishp@rivosinc.com>
In-Reply-To: <20240411000752.955910-1-atishp@rivosinc.com>
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The virtual counter value is updated during pmu_ctr_read. There is no need
to update it in reset case. Otherwise, it will be counted twice which is
incorrect.

Fixes: 0cb74b65d2e5 ("RISC-V: KVM: Implement perf support without sampling")
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/kvm/vcpu_pmu.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index cee1b9ca4ec4..b5159ce4592d 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -397,7 +397,6 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
 {
 	struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
 	int i, pmc_index, sbiret = 0;
-	u64 enabled, running;
 	struct kvm_pmc *pmc;
 	int fevent_code;
 
@@ -432,12 +431,9 @@ int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
 				sbiret = SBI_ERR_ALREADY_STOPPED;
 			}
 
-			if (flags & SBI_PMU_STOP_FLAG_RESET) {
-				/* Relase the counter if this is a reset request */
-				pmc->counter_val += perf_event_read_value(pmc->perf_event,
-									  &enabled, &running);
+			if (flags & SBI_PMU_STOP_FLAG_RESET)
+				/* Release the counter if this is a reset request */
 				kvm_pmu_release_perf_event(pmc);
-			}
 		} else {
 			sbiret = SBI_ERR_INVALID_PARAM;
 		}
-- 
2.34.1