The GIC sometimes need to sample the physical line of a mapped
interrupt. As we know this to be notoriously slow, provide a callback
function for devices (such as the timer) which can do this much faster
than talking to the distributor, for example by comparing a few
in-memory values. Fall back to the good old method of poking the
physical GIC if no callback is provided.
Signed-off-by: Christoffer Dall <cdall@xxxxxxxxxx>
---
include/kvm/arm_vgic.h | 13 ++++++++++++-
virt/kvm/arm/arch_timer.c | 16 +++++++++++++++-
virt/kvm/arm/vgic/vgic.c | 7 ++++++-
3 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 53f631b..a52990b 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -125,6 +125,17 @@ struct vgic_irq {
u8 priority;
enum vgic_irq_config config; /* Level or edge */
+ /*
+ * Callback function pointer to in-kernel devices that can tell us the
+ * state of the input level of mapped level-triggered IRQ faster than
+ * peaking into the physical GIC.
+ *
+ * Always called in non-preemptible section and the functions can use
+ * kvm_arm_get_running_vcpu() to get the vcpu pointer for private
+ * IRQs.
+ */
+ bool (*get_input_level)(int vintid);
+
void *owner; /* Opaque pointer to reserve an interrupt
for in-kernel devices. */
};
@@ -309,7 +320,7 @@ void kvm_vgic_init_cpu_hardware(void);
int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
bool level, void *owner);
int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
- u32 vintid);
+ u32 vintid, bool (*callback)(int vindid));
int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int vintid);
bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int vintid);
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index b24e2f7..82169ef 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -643,6 +643,19 @@ static bool timer_irqs_are_valid(struct kvm_vcpu *vcpu)
return true;
}
+static bool timer_get_input_level(int vintid)
+{
+ struct kvm_vcpu *vcpu = kvm_arm_get_running_vcpu();
+ struct arch_timer_context *timer;
+
+ if (vintid == vcpu_vtimer(vcpu)->irq.irq)
+ timer = vcpu_vtimer(vcpu);
+ else
+ BUG(); /* We only map the vtimer so far */
+
+ return kvm_timer_should_fire(timer);
+}
+
int kvm_timer_enable(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
@@ -664,7 +677,8 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
return -EINVAL;
}
- ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq, vtimer->irq.irq);
+ ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq, vtimer->irq.irq,
+ &timer_get_input_level);
if (ret)
return ret;
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index e3ce2fa..0466c10 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -147,6 +147,9 @@ bool vgic_irq_line_level(struct vgic_irq *irq)
BUG_ON(!irq->hw);
+ if (irq->get_input_level)
+ return irq->get_input_level(irq->intid);
+
WARN_ON(irq_get_irqchip_state(irq->host_irq,
IRQCHIP_STATE_PENDING,
&line_level));
@@ -429,7 +432,7 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
}
int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
- u32 vintid)
+ u32 vintid, bool (*callback)(int vindid))
{
struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, vintid);
struct irq_desc *desc;
@@ -456,6 +459,7 @@ int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
irq->hw = true;
irq->host_irq = host_irq;
irq->hwintid = data->hwirq;
+ irq->get_input_level = callback;
out:
spin_unlock(&irq->irq_lock);
@@ -476,6 +480,7 @@ int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int vintid)
spin_lock(&irq->irq_lock);
irq->hw = false;
irq->hwintid = 0;
+ irq->get_input_level = NULL;
spin_unlock(&irq->irq_lock);
vgic_put_irq(vcpu->kvm, irq);
--
2.9.0
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