From: Julien Thierry <julien.thierry@arm.com> To: linux-arm-kernel@lists.infradead.org Cc: mark.rutland@arm.com, Julien Thierry <julien.thierry@arm.com>, peterz@infradead.org, jolsa@redhat.com, Suzuki K Pouloze <suzuki.poulose@arm.com>, will.deacon@arm.com, Christoffer Dall <christoffer.dall@arm.com>, acme@kernel.org, alexander.shishkin@linux.intel.com, mingo@redhat.com, James Morse <james.morse@arm.com>, Marc Zyngier <marc.zyngier@arm.com>, namhyung@kernel.org, sthotton@marvell.com, liwei391@huawei.com, kvmarm@lists.cs.columbia.edu Subject: [PATCH v4 7/9] arm/arm64: kvm: pmu: Make overflow handler NMI safe Date: Wed, 17 Jul 2019 09:17:10 +0100 Message-ID: <1563351432-55652-8-git-send-email-julien.thierry@arm.com> (raw) In-Reply-To: <1563351432-55652-1-git-send-email-julien.thierry@arm.com> When using an NMI for the PMU interrupt, taking any lock might cause a deadlock. The current PMU overflow handler in KVM takes locks when trying to wake up a vcpu. When overflow handler is called by an NMI, defer the vcpu waking in an irq_work queue. Signed-off-by: Julien Thierry <julien.thierry@arm.com> Cc: Christoffer Dall <christoffer.dall@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Suzuki K Pouloze <suzuki.poulose@arm.com> Cc: kvmarm@lists.cs.columbia.edu --- include/kvm/arm_pmu.h | 1 + virt/kvm/arm/pmu.c | 25 ++++++++++++++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h index 16c769a..8202ed7 100644 --- a/include/kvm/arm_pmu.h +++ b/include/kvm/arm_pmu.h @@ -27,6 +27,7 @@ struct kvm_pmu { bool ready; bool created; bool irq_level; + struct irq_work overflow_work; }; #define kvm_arm_pmu_v3_ready(v) ((v)->arch.pmu.ready) diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c index 3dd8238..deed8fb 100644 --- a/virt/kvm/arm/pmu.c +++ b/virt/kvm/arm/pmu.c @@ -421,6 +421,22 @@ void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu) } /** + * When perf interrupt is an NMI, we cannot safely notify the vcpu corresponding + * to the event. + * This is why we need a callback to do it once outside of the NMI context. + */ +static void kvm_pmu_perf_overflow_notify_vcpu(struct irq_work *work) +{ + struct kvm_vcpu *vcpu; + struct kvm_pmu *pmu; + + pmu = container_of(work, struct kvm_pmu, overflow_work); + vcpu = kvm_pmc_to_vcpu(&pmu->pmc[0]); + + kvm_vcpu_kick(vcpu); +} + +/** * When the perf event overflows, set the overflow status and inform the vcpu. */ static void kvm_pmu_perf_overflow(struct perf_event *perf_event, @@ -435,7 +451,11 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event, if (kvm_pmu_overflow_status(vcpu)) { kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu); - kvm_vcpu_kick(vcpu); + + if (!in_nmi()) + kvm_vcpu_kick(vcpu); + else + irq_work_queue(&vcpu->arch.pmu.overflow_work); } } @@ -706,6 +726,9 @@ static int kvm_arm_pmu_v3_init(struct kvm_vcpu *vcpu) return ret; } + init_irq_work(&vcpu->arch.pmu.overflow_work, + kvm_pmu_perf_overflow_notify_vcpu); + vcpu->arch.pmu.created = true; return 0; } -- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply index Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-17 8:17 [PATCH v4 0/9] arm_pmu: Use NMI for perf interrupt Julien Thierry 2019-07-17 8:17 ` [PATCH v4 1/9] arm64: perf: avoid PMXEV* indirection Julien Thierry 2019-07-17 8:17 ` [PATCH v4 2/9] arm64: perf: Remove PMU locking Julien Thierry 2019-08-01 12:58 ` Will Deacon 2019-08-02 14:26 ` Julien Thierry 2019-07-17 8:17 ` [PATCH v4 3/9] arm: perf: save/resore pmsel Julien Thierry 2019-08-01 13:01 ` Will Deacon 2019-08-02 14:34 ` Julien Thierry 2019-07-17 8:17 ` [PATCH v4 4/9] arm: perf: Remove Remove PMU locking Julien Thierry 2019-08-01 13:06 ` Will Deacon 2019-08-02 14:36 ` Julien Thierry 2019-07-17 8:17 ` [PATCH v4 5/9] perf/arm_pmu: Move PMU lock to ARMv6 events Julien Thierry 2019-07-17 8:17 ` [PATCH v4 6/9] arm64: perf: Do not call irq_work_run in NMI context Julien Thierry 2019-08-01 13:06 ` Will Deacon 2019-08-02 14:43 ` Julien Thierry 2019-07-17 8:17 ` Julien Thierry [this message] 2019-07-17 8:17 ` [PATCH v4 8/9] arm_pmu: Introduce pmu_irq_ops Julien Thierry 2019-07-17 8:17 ` [PATCH v4 9/9] arm_pmu: Use NMIs for PMU Julien Thierry 2019-07-30 9:11 ` Russell King - ARM Linux admin 2019-07-30 9:18 ` Julien Thierry 2019-07-30 9:28 ` Russell King - ARM Linux admin 2019-07-30 14:06 ` Julien Thierry 2019-07-17 9:02 ` [PATCH v4 0/9] arm_pmu: Use NMI for perf interrupt Julien Thierry 2019-07-30 9:05 ` Julien Thierry
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