diff options
Diffstat (limited to 'virt/kvm/arm/arch_timer.c')
| -rw-r--r-- | virt/kvm/arm/arch_timer.c | 40 |
1 files changed, 37 insertions, 3 deletions
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c index 69bca185c471..a9ad4fe3f68f 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); @@ -143,7 +149,7 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level) * Check if there was a change in the timer state (should we raise or lower * the line level to the GIC). */ -static void kvm_timer_update_state(struct kvm_vcpu *vcpu) +static int kvm_timer_update_state(struct kvm_vcpu *vcpu) { struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu; @@ -154,10 +160,12 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu) * until we call this function from kvm_timer_flush_hwstate. */ if (!vgic_initialized(vcpu->kvm)) - return; + return -ENODEV; if (kvm_timer_should_fire(vcpu) != timer->irq.level) kvm_timer_update_irq(vcpu, !timer->irq.level); + + return 0; } /* @@ -218,7 +226,8 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu) bool phys_active; int ret; - kvm_timer_update_state(vcpu); + if (kvm_timer_update_state(vcpu)) + return; /* * If we enter the guest with the virtual input level to the VGIC @@ -242,10 +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; } /** |