From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Murray Subject: Re: [PATCH v2 3/5] KVM: arm/arm64: re-create event when setting counter value Date: Mon, 18 Feb 2019 09:39:44 +0000 Message-ID: <20190218093944.GE54124@e119886-lin.cambridge.arm.com> References: <1549299218-44714-1-git-send-email-andrew.murray@arm.com> <1549299218-44714-4-git-send-email-andrew.murray@arm.com> <3adc7d31-9d5a-d66b-21ee-9b4da986d24f@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id F3FDD4A331 for ; Mon, 18 Feb 2019 04:39:48 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5rtoL26f5CSa for ; Mon, 18 Feb 2019 04:39:47 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id DBDC840A52 for ; Mon, 18 Feb 2019 04:39:47 -0500 (EST) Content-Disposition: inline In-Reply-To: <3adc7d31-9d5a-d66b-21ee-9b4da986d24f@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Suzuki K Poulose Cc: marc.zyngier@arm.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu List-Id: kvmarm@lists.cs.columbia.edu On Wed, Feb 13, 2019 at 02:28:51PM +0000, Suzuki K Poulose wrote: > Hi Andrew, > > On 04/02/2019 16:53, Andrew Murray wrote: > > The perf event sample_period is currently set based upon the current > > counter value, when PMXEVTYPER is written to and the perf event is created. > > However the user may choose to write the type before the counter value in > > which case sample_period will be set incorrectly. Let's instead decouple > > event creation from PMXEVTYPER and (re)create the event in either > > suitation. > > > > Signed-off-by: Andrew Murray > > --- > > virt/kvm/arm/pmu.c | 40 +++++++++++++++++++++++++++++++--------- > > 1 file changed, 31 insertions(+), 9 deletions(-) > > > > diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c > > index 6e7c179..95d74ec 100644 > > --- a/virt/kvm/arm/pmu.c > > +++ b/virt/kvm/arm/pmu.c > > @@ -24,6 +24,7 @@ > > #include > > #include > > +static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx); > > /** > > * kvm_pmu_get_counter_value - get PMU counter value > > * @vcpu: The vcpu pointer > > @@ -62,6 +63,9 @@ void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val) > > reg = (select_idx == ARMV8_PMU_CYCLE_IDX) > > ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + select_idx; > > __vcpu_sys_reg(vcpu, reg) += (s64)val - kvm_pmu_get_counter_value(vcpu, select_idx); > > + > > + /* Recreate the perf event to reflect the updated sample_period */ > > + kvm_pmu_create_perf_event(vcpu, select_idx); > > } > > /** > > @@ -378,23 +382,22 @@ static bool kvm_pmu_counter_is_enabled(struct kvm_vcpu *vcpu, u64 select_idx) > > } > > /** > > - * kvm_pmu_set_counter_event_type - set selected counter to monitor some event > > + * kvm_pmu_create_perf_event - create a perf event for a counter > > * @vcpu: The vcpu pointer > > - * @data: The data guest writes to PMXEVTYPER_EL0 > > + * @data: Type of event as per PMXEVTYPER_EL0 format > > * @select_idx: The number of selected counter > > nit: data no longer exists. > Thanks for the review, Andrew Murray > > > - * > > - * When OS accesses PMXEVTYPER_EL0, that means it wants to set a PMC to count an > > - * event with given hardware event number. Here we call perf_event API to > > - * emulate this action and create a kernel perf event for it. > > */ > > -void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data, > > - u64 select_idx) > > +static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx) > > { > > With the comment from Julien addressed, > > Reviewed-by: Suzuki K Poulose