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From: Atish Patra <atishp@rivosinc.com>
To: linux-kernel@vger.kernel.org
Cc: Atish Patra <atishp@rivosinc.com>,
	Andrew Jones <ajones@ventanamicro.com>,
	Ajay Kaher <ajay.kaher@broadcom.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
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	Conor Dooley <conor.dooley@microchip.com>,
	Juergen Gross <jgross@suse.com>,
	kvm-riscv@lists.infradead.org,
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	Palmer Dabbelt <palmer@dabbelt.com>,
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	Shuah Khan <shuah@kernel.org>,
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	Will Deacon <will@kernel.org>,
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Subject: [PATCH v7 10/24] RISC-V: KVM: Fix the initial sample period value
Date: Tue, 16 Apr 2024 11:44:07 -0700
Message-Id: <20240416184421.3693802-11-atishp@rivosinc.com>
In-Reply-To: <20240416184421.3693802-1-atishp@rivosinc.com>
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The initial sample period value when counter value is not assigned
should be set to maximum value supported by the counter width.
Otherwise, it may result in spurious interrupts.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/kvm/vcpu_pmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 86391a5061dd..cee1b9ca4ec4 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -39,7 +39,7 @@ static u64 kvm_pmu_get_sample_period(struct kvm_pmc *pmc)
 	u64 sample_period;
 
 	if (!pmc->counter_val)
-		sample_period = counter_val_mask + 1;
+		sample_period = counter_val_mask;
 	else
 		sample_period = (-pmc->counter_val) & counter_val_mask;
 
-- 
2.34.1