When using an NMI for the PMU interrupt, taking any lock migh cause a deadlock. The current PMU overflow handler in KVM takes 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 <[email protected]> Cc: Christoffer Dall <[email protected]> Cc: Marc Zyngier <[email protected]> Cc: Will Deacon <[email protected]> Cc: Mark Rutland <[email protected]> Cc: James Morse <[email protected]> Cc: Suzuki K Pouloze <[email protected]> Cc: [email protected] --- include/kvm/arm_pmu.h | 1 + virt/kvm/arm/pmu.c | 37 +++++++++++++++++++++++++++++++++---- 2 files changed, 34 insertions(+), 4 deletions(-) diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h index f87fe20..6a7c9dd 100644 --- a/include/kvm/arm_pmu.h +++ b/include/kvm/arm_pmu.h @@ -37,6 +37,7 @@ 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 1c5b76c..a72c972 100644 --- a/virt/kvm/arm/pmu.c +++ b/virt/kvm/arm/pmu.c @@ -273,15 +273,37 @@ void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu) kvm_pmu_update_state(vcpu); } +static inline struct kvm_vcpu *kvm_pmu_to_vcpu(struct kvm_pmu *pmu) +{ + struct kvm_vcpu_arch *vcpu_arch; + + vcpu_arch = container_of(pmu, struct kvm_vcpu_arch, pmu); + return container_of(vcpu_arch, struct kvm_vcpu, arch); +} + static inline 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); + return kvm_pmu_to_vcpu(pmu); +} + +/** + * When perf interrupt is an NMI, we cannot safely notify the vcpu corresponding + * to the even. + * 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_pmu_to_vcpu(pmu); + + kvm_vcpu_kick(vcpu); } /** @@ -299,7 +321,11 @@ 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); } } @@ -501,6 +527,9 @@ 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 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
