KVM: arm/arm64: Support a vgic interrupt line level sample function

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.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 12 insertions, 1 deletions

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 8c896540a72c..cdbd142ca7f2 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -130,6 +130,17 @@ 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. */
 };
@@ -331,7 +342,7 @@ 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 (*get_input_level)(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);