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[34.82.181.220]) by smtp.gmail.com with ESMTPSA id g74-20020a62524d000000b0056bb4bbfb9bsm8195038pfb.95.2022.12.13.10.22.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Dec 2022 10:22:49 -0800 (PST) Date: Tue, 13 Dec 2022 10:22:45 -0800 From: Ricardo Koller To: Oliver Upton Cc: James Clark , Will Deacon , Marc Zyngier , linux-kernel@vger.kernel.org, Catalin Marinas , kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 1/1] KVM: arm64: PMU: Fix PMCR_EL0 reset value Message-ID: References: <20221209164446.1972014-1-james.clark@arm.com> <20221209164446.1972014-2-james.clark@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 09, 2022 at 05:58:31PM +0000, Oliver Upton wrote: > On Fri, Dec 09, 2022 at 04:44:46PM +0000, James Clark wrote: > > ARMV8_PMU_PMCR_N_MASK is an unshifted value which results in the wrong > > reset value for PMCR_EL0, so shift it to fix it. > > That's just mean. *_MASK tends to be a shifted mask, although it would > appear that asm/perf_event.h does not follow this convention. Fixing > that would be nice (as I'm sure somebody else will get burned by this), > but for the sake of an immediate fix: > Even kvm-unit-tests does this: arm/pmu.c: #define PMU_PMCR_N_SHIFT 11 #define PMU_PMCR_N_MASK 0x1f > > This fixes the following error when running qemu: > > > > $ qemu-system-aarch64 -cpu host -machine type=virt,accel=kvm -kernel ... > > > > target/arm/helper.c:1813: pmevcntr_rawwrite: Assertion `counter < pmu_num_counters(env)' failed. > > > > Fixes: 292e8f149476 ("KVM: arm64: PMU: Simplify PMCR_EL0 reset handling") > > Signed-off-by: James Clark > > Reviewed-by: Oliver Upton > > -- > Thanks, > Oliver > > > --- > > arch/arm64/kvm/sys_regs.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > > index d5ee52d6bf73..c6cbfe6b854b 100644 > > --- a/arch/arm64/kvm/sys_regs.c > > +++ b/arch/arm64/kvm/sys_regs.c > > @@ -646,7 +646,7 @@ static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) > > return; > > > > /* Only preserve PMCR_EL0.N, and reset the rest to 0 */ > > - pmcr = read_sysreg(pmcr_el0) & ARMV8_PMU_PMCR_N_MASK; > > + pmcr = read_sysreg(pmcr_el0) & (ARMV8_PMU_PMCR_N_MASK << ARMV8_PMU_PMCR_N_SHIFT); > > if (!kvm_supports_32bit_el0()) > > pmcr |= ARMV8_PMU_PMCR_LC; > > > > -- > > 2.25.1 > > > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm