From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FC69C04AAF for ; Tue, 21 May 2019 16:46:39 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id B09692173E for ; Tue, 21 May 2019 16:46:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B09692173E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3DC254A4C3; Tue, 21 May 2019 12:46:38 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu 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 zD28hTmZgs1n; Tue, 21 May 2019 12:46:36 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 028BF4A4BE; Tue, 21 May 2019 12:46:36 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 184F94A4A4 for ; Tue, 21 May 2019 12:46:34 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu 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 PWDD1lNSP7wR for ; Tue, 21 May 2019 12:46:32 -0400 (EDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 5BC564A477 for ; Tue, 21 May 2019 12:46:32 -0400 (EDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CE9DE374; Tue, 21 May 2019 09:46:31 -0700 (PDT) Received: from [10.37.9.19] (unknown [10.37.9.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4D3753F718; Tue, 21 May 2019 09:46:30 -0700 (PDT) Subject: Re: [PATCH v7 5/5] KVM: arm/arm64: support chained PMU counters To: Andrew Murray , Christoffer Dall , Marc Zyngier References: <20190521155228.903-1-andrew.murray@arm.com> <20190521155228.903-6-andrew.murray@arm.com> From: Julien Thierry Message-ID: Date: Tue, 21 May 2019 17:46:28 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190521155228.903-6-andrew.murray@arm.com> Content-Language: en-US Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Andrew, On 05/21/2019 04:52 PM, Andrew Murray wrote: > ARMv8 provides support for chained PMU counters, where an event type > of 0x001E is set for odd-numbered counters, the event counter will > increment by one for each overflow of the preceding even-numbered > counter. Let's emulate this in KVM by creating a 64 bit perf counter > when a user chains two emulated counters together. > > For chained events we only support generating an overflow interrupt > on the high counter. We use the attributes of the low counter to > determine the attributes of the perf event. > > Suggested-by: Marc Zyngier > Signed-off-by: Andrew Murray > --- > include/kvm/arm_pmu.h | 2 + > virt/kvm/arm/pmu.c | 246 ++++++++++++++++++++++++++++++++++++------ > 2 files changed, 215 insertions(+), 33 deletions(-) > > diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h > index b73f31baca52..8b434745500a 100644 > --- a/include/kvm/arm_pmu.h > +++ b/include/kvm/arm_pmu.h > @@ -22,6 +22,7 @@ > #include > > #define ARMV8_PMU_CYCLE_IDX (ARMV8_PMU_MAX_COUNTERS - 1) > +#define ARMV8_PMU_MAX_COUNTER_PAIRS ((ARMV8_PMU_MAX_COUNTERS + 1) >> 1) > > #ifdef CONFIG_KVM_ARM_PMU > > @@ -34,6 +35,7 @@ struct kvm_pmc { > struct kvm_pmu { > int irq_num; > struct kvm_pmc pmc[ARMV8_PMU_MAX_COUNTERS]; > + DECLARE_BITMAP(chained, ARMV8_PMU_MAX_COUNTER_PAIRS); > bool ready; > bool created; > bool irq_level; > diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c > index ae1e886d4a1a..4b0981c402c6 100644 > --- a/virt/kvm/arm/pmu.c > +++ b/virt/kvm/arm/pmu.c > @@ -25,28 +25,128 @@ > #include > > static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx); > + > +#define PERF_ATTR_CFG1_KVM_PMU_CHAINED 0x1 > + > +static struct kvm_vcpu *kvm_pmc_to_vcpu(struct kvm_pmc *pmc) > +{ > + struct kvm_pmu *pmu; > + struct kvm_vcpu_arch *vcpu_arch; > + > + pmc -= pmc->idx; > + pmu = container_of(pmc, struct kvm_pmu, pmc[0]); > + vcpu_arch = container_of(pmu, struct kvm_vcpu_arch, pmu); > + return container_of(vcpu_arch, struct kvm_vcpu, arch); > +} > + > /** > - * kvm_pmu_get_counter_value - get PMU counter value > + * kvm_pmu_pmc_is_chained - determine if the pmc is chained > + * @pmc: The PMU counter pointer > + */ > +static bool kvm_pmu_pmc_is_chained(struct kvm_pmc *pmc) > +{ > + struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc); > + > + return test_bit(pmc->idx >> 1, vcpu->arch.pmu.chained); > +} > + > +/** > + * kvm_pmu_pmc_is_high_counter - determine if select_idx is a high/low counter > + * @select_idx: The counter index > + */ > +static bool kvm_pmu_pmc_is_high_counter(u64 select_idx) > +{ > + return select_idx & 0x1; > +} > + > +/** > + * kvm_pmu_get_canonical_pmc - obtain the canonical pmc > + * @pmc: The PMU counter pointer > + * > + * When a pair of PMCs are chained together we use the low counter (canonical) > + * to hold the underlying perf event. > + */ > +static struct kvm_pmc *kvm_pmu_get_canonical_pmc(struct kvm_pmc *pmc) > +{ > + if (kvm_pmu_pmc_is_chained(pmc) && > + kvm_pmu_pmc_is_high_counter(pmc->idx)) > + return pmc - 1; > + > + return pmc; > +} > + > +/** > + * kvm_pmu_idx_has_chain_evtype - determine if the event type is chain > * @vcpu: The vcpu pointer > * @select_idx: The counter index > */ > -u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx) > +static bool kvm_pmu_idx_has_chain_evtype(struct kvm_vcpu *vcpu, u64 select_idx) > { > - u64 counter, reg, enabled, running; > - struct kvm_pmu *pmu = &vcpu->arch.pmu; > - struct kvm_pmc *pmc = &pmu->pmc[select_idx]; > + u64 eventsel, reg; > > - reg = (select_idx == ARMV8_PMU_CYCLE_IDX) > - ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + select_idx; > - counter = __vcpu_sys_reg(vcpu, reg); > + select_idx |= 0x1; > + > + if (select_idx == ARMV8_PMU_CYCLE_IDX) > + return false; > + > + reg = PMEVTYPER0_EL0 + select_idx; > + eventsel = __vcpu_sys_reg(vcpu, reg) & ARMV8_PMU_EVTYPE_EVENT; > + > + return armv8pmu_evtype_is_chain(eventsel); > +} > + > +/** > + * kvm_pmu_get_pair_counter_value - get PMU counter value > + * @vcpu: The vcpu pointer > + * @pmc: The PMU counter pointer > + */ > +static u64 kvm_pmu_get_pair_counter_value(struct kvm_vcpu *vcpu, > + struct kvm_pmc *pmc) > +{ > + u64 counter, counter_high, reg, enabled, running; > + > + if (kvm_pmu_pmc_is_chained(pmc)) { > + pmc = kvm_pmu_get_canonical_pmc(pmc); > + reg = PMEVCNTR0_EL0 + pmc->idx; > + > + counter = __vcpu_sys_reg(vcpu, reg); > + counter_high = __vcpu_sys_reg(vcpu, reg + 1); > + > + counter = lower_32_bits(counter) | (counter_high << 32); > + } else { > + reg = (pmc->idx == ARMV8_PMU_CYCLE_IDX) > + ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + pmc->idx; > + counter = __vcpu_sys_reg(vcpu, reg); > + } > > - /* The real counter value is equal to the value of counter register plus > + /* > + * The real counter value is equal to the value of counter register plus > * the value perf event counts. > */ > if (pmc->perf_event) > counter += perf_event_read_value(pmc->perf_event, &enabled, > &running); > > + return counter; > +} > + > +/** > + * kvm_pmu_get_counter_value - get PMU counter value > + * @vcpu: The vcpu pointer > + * @select_idx: The counter index > + */ > +u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx) > +{ > + u64 counter; > + struct kvm_pmu *pmu = &vcpu->arch.pmu; > + struct kvm_pmc *pmc = &pmu->pmc[select_idx]; > + > + counter = kvm_pmu_get_pair_counter_value(vcpu, pmc); > + > + if (kvm_pmu_pmc_is_chained(pmc) && > + kvm_pmu_pmc_is_high_counter(select_idx)) > + counter >>= 32; > + > return counter & pmc->bitmask; > } > > @@ -74,6 +174,7 @@ void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val) > */ > static void kvm_pmu_release_perf_event(struct kvm_pmc *pmc) > { > + pmc = kvm_pmu_get_canonical_pmc(pmc); > if (pmc->perf_event) { > perf_event_disable(pmc->perf_event); > perf_event_release_kernel(pmc->perf_event); > @@ -91,13 +192,24 @@ static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc) > { > u64 counter, reg; > > - if (pmc->perf_event) { > + pmc = kvm_pmu_get_canonical_pmc(pmc); > + if (!pmc->perf_event) > + return; > + > + if (kvm_pmu_pmc_is_chained(pmc)) { > + counter = kvm_pmu_get_pair_counter_value(vcpu, pmc); > + > + reg = PMEVCNTR0_EL0 + pmc->idx; > + __vcpu_sys_reg(vcpu, reg) = counter & pmc->bitmask; > + __vcpu_sys_reg(vcpu, reg + 1) = (counter >> 32) & pmc->bitmask; > + } else { > counter = kvm_pmu_get_counter_value(vcpu, pmc->idx); > reg = (pmc->idx == ARMV8_PMU_CYCLE_IDX) > ? PMCCNTR_EL0 : PMEVCNTR0_EL0 + pmc->idx; > __vcpu_sys_reg(vcpu, reg) = counter; > - kvm_pmu_release_perf_event(pmc); > } > + > + kvm_pmu_release_perf_event(pmc); > } > > /** > @@ -115,6 +227,8 @@ void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu) > pmu->pmc[i].idx = i; > pmu->pmc[i].bitmask = 0xffffffffUL; > } > + > + bitmap_zero(vcpu->arch.pmu.chained, ARMV8_PMU_MAX_COUNTER_PAIRS); > } > > /** > @@ -154,6 +268,7 @@ void kvm_pmu_enable_counter_mask(struct kvm_vcpu *vcpu, u64 val) > int i; > struct kvm_pmu *pmu = &vcpu->arch.pmu; > struct kvm_pmc *pmc; > + struct perf_event *perf_event; > > if (!(__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E) || !val) > return; > @@ -163,9 +278,21 @@ void kvm_pmu_enable_counter_mask(struct kvm_vcpu *vcpu, u64 val) > continue; > > pmc = &pmu->pmc[i]; > + > + /* > + * For high counters of chained events we must recreate the > + * perf event with the long (64bit) attribute set. > + */ > + if (kvm_pmu_pmc_is_chained(pmc) && > + kvm_pmu_pmc_is_high_counter(i)) { > + kvm_pmu_create_perf_event(vcpu, i); > + continue; > + } > + > + pmc = kvm_pmu_get_canonical_pmc(pmc); But pmc is already a canonical pmc, we don't need to call kvm_pmu_get_canonical_pmc(). The condition above is the same as the one use in kvm_pmu_get_canonical_pmc(), so no "non canonical" pmc ever reaches that point. I would understand putting a comment to clarify that fact. > if (pmc->perf_event) { > perf_event_enable(pmc->perf_event); > - if (pmc->perf_event->state != PERF_EVENT_STATE_ACTIVE) > + if (perf_event->state != PERF_EVENT_STATE_ACTIVE) You forgot to set perf_event. > kvm_debug("fail to enable perf event\n"); > } > } > @@ -192,6 +319,18 @@ void kvm_pmu_disable_counter_mask(struct kvm_vcpu *vcpu, u64 val) > continue; > > pmc = &pmu->pmc[i]; > + > + /* > + * For high counters of chained events we must recreate the > + * perf event with the long (64bit) attribute unset. > + */ > + if (kvm_pmu_pmc_is_chained(pmc) && > + kvm_pmu_pmc_is_high_counter(i)) { > + kvm_pmu_create_perf_event(vcpu, i); > + continue; > + } > + > + pmc = kvm_pmu_get_canonical_pmc(pmc); Same as the enable case, we know pmc is already canonical, no need to call the function. Thanks, -- Julien Thierry _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm