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Sun, 09 Mar 2025 18:50:03 +0000 Date: Sun, 09 Mar 2025 18:50:02 +0000 Message-ID: <865xkiox7p.wl-maz@kernel.org> From: Marc Zyngier To: Akihiko Odaki Cc: Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Andrew Jones , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, devel@daynix.com Subject: Re: [PATCH v2 2/3] KVM: arm64: PMU: Reload when user modifies registers In-Reply-To: <20250307-pmc-v2-2-6c3375a5f1e4@daynix.com> References: <20250307-pmc-v2-0-6c3375a5f1e4@daynix.com> <20250307-pmc-v2-2-6c3375a5f1e4@daynix.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: akihiko.odaki@daynix.com, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, andrew.jones@linux.dev, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, devel@daynix.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250309_115009_545579_C8A4E73D X-CRM114-Status: GOOD ( 22.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org [dropping Shannon from the list, as his Linaro email has been bouncing for about 10 years, and updating Andrew's email] On Fri, 07 Mar 2025 10:55:29 +0000, Akihiko Odaki wrote: > > Commit d0c94c49792c ("KVM: arm64: Restore PMU configuration on first > run") added the code to reload the PMU configuration on first run. > Trigger the code when a user modifies a PMU register instead so that > PMU configuration changes made by users will be applied also after the > first run. > > Signed-off-by: Akihiko Odaki > --- > arch/arm64/kvm/pmu-emul.c | 3 --- > arch/arm64/kvm/sys_regs.c | 5 +++++ > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c > index 1402cce5625bffa706aabe5e6121d1f3817a0aaf..04eb3856b96576fad5afc8927c8916ff9738f9d7 100644 > --- a/arch/arm64/kvm/pmu-emul.c > +++ b/arch/arm64/kvm/pmu-emul.c > @@ -888,9 +888,6 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu) > return -EINVAL; > } > > - /* One-off reload of the PMU on first run */ > - kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu); > - > return 0; > } > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 27418dac791df9a89124f867879e899db175e506..51054b7befc0b4bd822cecf717ee4a4740c4a685 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -1162,6 +1162,8 @@ static int set_pmreg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, u64 va > else > __vcpu_sys_reg(vcpu, r->reg) &= ~val; > > + kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu); > + > return 0; > } > > @@ -1322,6 +1324,8 @@ static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, > val |= ARMV8_PMU_PMCR_LC; > > __vcpu_sys_reg(vcpu, r->reg) = val; > + kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu); > + > return 0; > } > > @@ -4276,6 +4280,7 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu) > } > > set_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &kvm->arch.flags); > + kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu); This should be restricted to cases where a PMU is actually available. But I also wonder what the motivation is to move this from first run to reset? Nothing explains it in the commit message. Thanks, M. -- Without deviation from the norm, progress is not possible.