linux-kernel - [PATCH 1/4] RISC-V: KVM: Disable the kernel perf counter during configure

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Message-Id: <20250226-kvm_pmu_improve-v1-1-74c058c2bf6d@rivosinc.com>
Date: Wed, 26 Feb 2025 12:25:03 -0800
From: Atish Patra <atishp@...osinc.com>
To: Anup Patel <anup@...infault.org>, Atish Patra <atishp@...shpatra.org>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Andrew Jones <ajones@...tanamicro.com>, 
 Paolo Bonzini <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>
Cc: kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, 
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, Atish Patra <atishp@...osinc.com>
Subject: [PATCH 1/4] RISC-V: KVM: Disable the kernel perf counter during
 configure

The perf event should be marked disabled during the creation as
it is not ready to be scheduled until there is SBI PMU start call
or config matching is called with auto start. Otherwise, event add/start
gets called during perf_event_create_kernel_counter function.
It will be enabled and scheduled to run via perf_event_enable during
either the above mentioned scenario.

Fixes: 0cb74b65d2e5 ("RISC-V: KVM: Implement perf support without sampling")

Signed-off-by: Atish Patra <atishp@...osinc.com>
---
 arch/riscv/kvm/vcpu_pmu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
index 2707a51b082c..78ac3216a54d 100644
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -666,6 +666,7 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
 		.type = etype,
 		.size = sizeof(struct perf_event_attr),
 		.pinned = true,
+		.disabled = true,
 		/*
 		 * It should never reach here if the platform doesn't support the sscofpmf
 		 * extension as mode filtering won't work without it.

-- 
2.43.0