diff options
| -rw-r--r-- | arch/arm/kvm/arm.c | 1 | ||||
| -rw-r--r-- | include/kvm/arm_arch_timer.h | 5 | ||||
| -rw-r--r-- | virt/kvm/arm/arch_timer.c | 31 |
3 files changed, 37 insertions, 0 deletions
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 75c7fed..9ca653e 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -322,6 +322,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) vcpu->cpu = -1; kvm_arm_set_running_vcpu(NULL); + kvm_timer_vcpu_put(vcpu); } int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu, diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h index 1800227..b651aed 100644 --- a/include/kvm/arm_arch_timer.h +++ b/include/kvm/arm_arch_timer.h @@ -55,6 +55,9 @@ struct arch_timer_cpu { /* VGIC mapping */ struct irq_phys_map *map; + + /* Active IRQ state caching */ + bool active_cleared_last; }; int kvm_timer_hyp_init(void); @@ -74,4 +77,6 @@ bool kvm_timer_should_fire(struct kvm_vcpu *vcpu); void kvm_timer_schedule(struct kvm_vcpu *vcpu); void kvm_timer_unschedule(struct kvm_vcpu *vcpu); +void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu); + #endif diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index ea60646..a9ad4fe 100644 --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -34,6 +34,11 @@ static struct timecounter *timecounter; static struct workqueue_struct *wqueue; static unsigned int host_vtimer_irq; +void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) +{ + vcpu->arch.timer_cpu.active_cleared_last = false; +} + static cycle_t kvm_phys_timer_read(void) { return timecounter->cc->read(timecounter->cc); @@ -130,6 +135,7 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level) BUG_ON(!vgic_initialized(vcpu->kvm)); + timer->active_cleared_last = false; timer->irq.level = new_level; trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->map->virt_irq, timer->irq.level); @@ -245,10 +251,35 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) else phys_active = false; + /* + * We want to avoid hitting the (re)distributor as much as + * possible, as this is a potentially expensive MMIO access + * (not to mention locks in the irq layer), and a solution for + * this is to cache the "active" state in memory. + * + * Things to consider: we cannot cache an "active set" state, + * because the HW can change this behind our back (it becomes + * "clear" in the HW). We must then restrict the caching to + * the "clear" state. + * + * The cache is invalidated on: + * - vcpu put, indicating that the HW cannot be trusted to be + * in a sane state on the next vcpu load, + * - any change in the interrupt state + * + * Usage conditions: + * - cached value is "active clear" + * - value to be programmed is "active clear" + */ + if (timer->active_cleared_last && !phys_active) + return; + ret = irq_set_irqchip_state(timer->map->irq, IRQCHIP_STATE_ACTIVE, phys_active); WARN_ON(ret); + + timer->active_cleared_last = !phys_active; } /** |
