From: Andrew Jones <[email protected]> kvm_pmu_overflow_set() is called from perf's interrupt handler, making the call of kvm_vgic_inject_irq() from it introduced with "KVM: arm/arm64: PMU: remove request-less vcpu kick" a really bad idea, as it's quite easy to try and retake a lock that the interrupted context is already holding. The fix is to use a vcpu kick, leaving the interrupt injection to kvm_pmu_sync_hwstate(), like it was doing before the refactoring. We don't just revert, though, because before the kick was request-less, leaving the vcpu exposed to the request-less vcpu kick race, and also because the kick was used unnecessarily from register access handlers.
Reviewed-by: Christoffer Dall <[email protected]> Signed-off-by: Andrew Jones <[email protected]> Signed-off-by: Marc Zyngier <[email protected]> --- arch/arm64/kvm/sys_regs.c | 2 +- include/kvm/arm_pmu.h | 2 -- virt/kvm/arm/pmu.c | 43 +++++++++++++++---------------------------- 3 files changed, 16 insertions(+), 31 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 77862881ae86..2e070d3baf9f 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -764,7 +764,7 @@ static bool access_pmovs(struct kvm_vcpu *vcpu, struct sys_reg_params *p, if (p->is_write) { if (r->CRm & 0x2) /* accessing PMOVSSET_EL0 */ - kvm_pmu_overflow_set(vcpu, p->regval & mask); + vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= (p->regval & mask); else /* accessing PMOVSCLR_EL0 */ vcpu_sys_reg(vcpu, PMOVSSET_EL0) &= ~(p->regval & mask); diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h index f6e030617467..f87fe20fcb05 100644 --- a/include/kvm/arm_pmu.h +++ b/include/kvm/arm_pmu.h @@ -48,7 +48,6 @@ void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu); void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu); void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val); void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val); -void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val); void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu); void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu); bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu); @@ -86,7 +85,6 @@ static inline void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu) {} static inline void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu) {} static inline void kvm_pmu_disable_counter(struct kvm_vcpu *vcpu, u64 val) {} static inline void kvm_pmu_enable_counter(struct kvm_vcpu *vcpu, u64 val) {} -static inline void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val) {} static inline void kvm_pmu_flush_hwstate(struct kvm_vcpu *vcpu) {} static inline void kvm_pmu_sync_hwstate(struct kvm_vcpu *vcpu) {} static inline bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu) diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c index fc8a723ff387..8a9c42366db7 100644 --- a/virt/kvm/arm/pmu.c +++ b/virt/kvm/arm/pmu.c @@ -203,11 +203,15 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu) return reg; } -static void kvm_pmu_check_overflow(struct kvm_vcpu *vcpu) +static void kvm_pmu_update_state(struct kvm_vcpu *vcpu) { struct kvm_pmu *pmu = &vcpu->arch.pmu; - bool overflow = !!kvm_pmu_overflow_status(vcpu); + bool overflow; + + if (!kvm_arm_pmu_v3_ready(vcpu)) + return; + overflow = !!kvm_pmu_overflow_status(vcpu); if (pmu->irq_level == overflow) return; @@ -215,33 +219,11 @@ static void kvm_pmu_check_overflow(struct kvm_vcpu *vcpu) if (likely(irqchip_in_kernel(vcpu->kvm))) { int ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id, - pmu->irq_num, overflow, - &vcpu->arch.pmu); + pmu->irq_num, overflow, pmu); WARN_ON(ret); } } -/** - * kvm_pmu_overflow_set - set PMU overflow interrupt - * @vcpu: The vcpu pointer - * @val: the value guest writes to PMOVSSET register - */ -void kvm_pmu_overflow_set(struct kvm_vcpu *vcpu, u64 val) -{ - if (val == 0) - return; - - vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= val; - kvm_pmu_check_overflow(vcpu); -} - -static void kvm_pmu_update_state(struct kvm_vcpu *vcpu) -{ - if (!kvm_arm_pmu_v3_ready(vcpu)) - return; - kvm_pmu_check_overflow(vcpu); -} - bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu) { struct kvm_pmu *pmu = &vcpu->arch.pmu; @@ -303,7 +285,7 @@ static inline struct kvm_vcpu *kvm_pmc_to_vcpu(struct kvm_pmc *pmc) } /** - * When perf event overflows, call kvm_pmu_overflow_set to set overflow status. + * When the perf event overflows, set the overflow status and inform the vcpu. */ static void kvm_pmu_perf_overflow(struct perf_event *perf_event, struct perf_sample_data *data, @@ -313,7 +295,12 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event, struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc); int idx = pmc->idx; - kvm_pmu_overflow_set(vcpu, BIT(idx)); + vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(idx); + + if (kvm_pmu_overflow_status(vcpu)) { + kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu); + kvm_vcpu_kick(vcpu); + } } /** @@ -341,7 +328,7 @@ void kvm_pmu_software_increment(struct kvm_vcpu *vcpu, u64 val) reg = lower_32_bits(reg); vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg; if (!reg) - kvm_pmu_overflow_set(vcpu, BIT(i)); + vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(i); } } } -- 2.11.0 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
