linux-kernel - [PATCH 2/4] KVM: riscv: selftests: Do not start the counter in the overflow handler

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250226-kvm_pmu_improve-v1-2-74c058c2bf6d@rivosinc.com>
Date: Wed, 26 Feb 2025 12:25:04 -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 2/4] KVM: riscv: selftests: Do not start the counter in the
 overflow handler

There is no need to start the counter in the overflow handler as we
intend to trigger precise number of LCOFI interrupts through these
tests. The overflow irq handler has already stopped the counter. As
a result, the stop call from the test function may return already
supported error which is fine as well.

Signed-off-by: Atish Patra <atishp@...osinc.com>
---
 tools/testing/selftests/kvm/riscv/sbi_pmu_test.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
index f45c0ecc902d..284bc80193bd 100644
--- a/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
+++ b/tools/testing/selftests/kvm/riscv/sbi_pmu_test.c
@@ -118,8 +118,8 @@ static void stop_counter(unsigned long counter, unsigned long stop_flags)
 
 	ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_COUNTER_STOP, counter, 1, stop_flags,
 			0, 0, 0);
-	__GUEST_ASSERT(ret.error == 0, "Unable to stop counter %ld error %ld\n",
-			       counter, ret.error);
+	__GUEST_ASSERT(ret.error == 0 || ret.error == SBI_ERR_ALREADY_STOPPED,
+		       "Unable to stop counter %ld error %ld\n", counter, ret.error);
 }
 
 static void guest_illegal_exception_handler(struct ex_regs *regs)
@@ -137,7 +137,6 @@ static void guest_irq_handler(struct ex_regs *regs)
 	unsigned int irq_num = regs->cause & ~CAUSE_IRQ_FLAG;
 	struct riscv_pmu_snapshot_data *snapshot_data = snapshot_gva;
 	unsigned long overflown_mask;
-	unsigned long counter_val = 0;
 
 	/* Validate that we are in the correct irq handler */
 	GUEST_ASSERT_EQ(irq_num, IRQ_PMU_OVF);
@@ -151,10 +150,6 @@ static void guest_irq_handler(struct ex_regs *regs)
 	GUEST_ASSERT(overflown_mask & 0x01);
 
 	WRITE_ONCE(vcpu_shared_irq_count, vcpu_shared_irq_count+1);
-
-	counter_val = READ_ONCE(snapshot_data->ctr_values[0]);
-	/* Now start the counter to mimick the real driver behavior */
-	start_counter(counter_in_use, SBI_PMU_START_FLAG_SET_INIT_VALUE, counter_val);
 }
 
 static unsigned long get_counter_index(unsigned long cbase, unsigned long cmask,

-- 
2.43.0