KVM: arm/arm64: vgic-new: Add IRQ sync/flush framework

Implement the framework for syncing IRQs between our emulation and
the list registers, which represent the guest's view of IRQs.
This is done in kvm_vgic_flush_hwstate and kvm_vgic_sync_hwstate,
which gets called on guest entry and exit.
The code talking to the actual GICv2/v3 hardware is added in the
following patches.

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

diff --git a/include/kvm/vgic/vgic.h b/include/kvm/vgic/vgic.h
index 7b6ca90..9506267 100644 (file)
--- a/include/kvm/vgic/vgic.h
+++ b/include/kvm/vgic/vgic.h
@@ -190,6 +190,10 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 #define vgic_valid_spi(k, i)   (((i) >= VGIC_NR_PRIVATE_IRQS) && \
                        ((i) < (k)->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS))
 
+bool kvm_vcpu_has_pending_irqs(struct kvm_vcpu *vcpu);
+void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);
+void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu);
+
 /**
  * kvm_vgic_get_max_vcpus - Get the maximum number of VCPUs allowed by HW
  *

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index bce17de..08a862a 100644 (file)
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -307,3 +307,195 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 {
        return vgic_update_irq_pending(kvm, cpuid, intid, level, false);
 }
+
+/**
+ * vgic_prune_ap_list - Remove non-relevant interrupts from the list
+ *
+ * @vcpu: The VCPU pointer
+ *
+ * Go over the list of "interesting" interrupts, and prune those that we
+ * won't have to consider in the near future.
+ */
+static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
+{
+       struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+       struct vgic_irq *irq, *tmp;
+
+retry:
+       spin_lock(&vgic_cpu->ap_list_lock);
+
+       list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
+               struct kvm_vcpu *target_vcpu, *vcpuA, *vcpuB;
+
+               spin_lock(&irq->irq_lock);
+
+               BUG_ON(vcpu != irq->vcpu);
+
+               target_vcpu = vgic_target_oracle(irq);
+
+               if (!target_vcpu) {
+                       /*
+                        * We don't need to process this interrupt any
+                        * further, move it off the list.
+                        */
+                       list_del(&irq->ap_list);
+                       irq->vcpu = NULL;
+                       spin_unlock(&irq->irq_lock);
+                       continue;
+               }
+
+               if (target_vcpu == vcpu) {
+                       /* We're on the right CPU */
+                       spin_unlock(&irq->irq_lock);
+                       continue;
+               }
+
+               /* This interrupt looks like it has to be migrated. */
+
+               spin_unlock(&irq->irq_lock);
+               spin_unlock(&vgic_cpu->ap_list_lock);
+
+               /*
+                * Ensure locking order by always locking the smallest
+                * ID first.
+                */
+               if (vcpu->vcpu_id < target_vcpu->vcpu_id) {
+                       vcpuA = vcpu;
+                       vcpuB = target_vcpu;
+               } else {
+                       vcpuA = target_vcpu;
+                       vcpuB = vcpu;
+               }
+
+               spin_lock(&vcpuA->arch.vgic_cpu.ap_list_lock);
+               spin_lock_nested(&vcpuB->arch.vgic_cpu.ap_list_lock,
+                                SINGLE_DEPTH_NESTING);
+               spin_lock(&irq->irq_lock);
+
+               /*
+                * If the affinity has been preserved, move the
+                * interrupt around. Otherwise, it means things have
+                * changed while the interrupt was unlocked, and we
+                * need to replay this.
+                *
+                * In all cases, we cannot trust the list not to have
+                * changed, so we restart from the beginning.
+                */
+               if (target_vcpu == vgic_target_oracle(irq)) {
+                       struct vgic_cpu *new_cpu = &target_vcpu->arch.vgic_cpu;
+
+                       list_del(&irq->ap_list);
+                       irq->vcpu = target_vcpu;
+                       list_add_tail(&irq->ap_list, &new_cpu->ap_list_head);
+               }
+
+               spin_unlock(&irq->irq_lock);
+               spin_unlock(&vcpuB->arch.vgic_cpu.ap_list_lock);
+               spin_unlock(&vcpuA->arch.vgic_cpu.ap_list_lock);
+               goto retry;
+       }
+
+       spin_unlock(&vgic_cpu->ap_list_lock);
+}
+
+static inline void vgic_process_maintenance_interrupt(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
+{
+}
+
+/* Requires the irq_lock to be held. */
+static inline void vgic_populate_lr(struct kvm_vcpu *vcpu,
+                                   struct vgic_irq *irq, int lr)
+{
+       DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
+}
+
+static inline void vgic_clear_lr(struct kvm_vcpu *vcpu, int lr)
+{
+}
+
+static inline void vgic_set_underflow(struct kvm_vcpu *vcpu)
+{
+}
+
+/* Requires the ap_list_lock to be held. */
+static int compute_ap_list_depth(struct kvm_vcpu *vcpu)
+{
+       struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+       struct vgic_irq *irq;
+       int count = 0;
+
+       DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
+
+       list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
+               spin_lock(&irq->irq_lock);
+               /* GICv2 SGIs can count for more than one... */
+               if (vgic_irq_is_sgi(irq->intid) && irq->source)
+                       count += hweight8(irq->source);
+               else
+                       count++;
+               spin_unlock(&irq->irq_lock);
+       }
+       return count;
+}
+
+/* Requires the VCPU's ap_list_lock to be held. */
+static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
+{
+       struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+       struct vgic_irq *irq;
+       int count = 0;
+
+       DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
+
+       if (compute_ap_list_depth(vcpu) > kvm_vgic_global_state.nr_lr) {
+               vgic_set_underflow(vcpu);
+               vgic_sort_ap_list(vcpu);
+       }
+
+       list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
+               spin_lock(&irq->irq_lock);
+
+               if (unlikely(vgic_target_oracle(irq) != vcpu))
+                       goto next;
+
+               /*
+                * If we get an SGI with multiple sources, try to get
+                * them in all at once.
+                */
+               do {
+                       vgic_populate_lr(vcpu, irq, count++);
+               } while (irq->source && count < kvm_vgic_global_state.nr_lr);
+
+next:
+               spin_unlock(&irq->irq_lock);
+
+               if (count == kvm_vgic_global_state.nr_lr)
+                       break;
+       }
+
+       vcpu->arch.vgic_cpu.used_lrs = count;
+
+       /* Nuke remaining LRs */
+       for ( ; count < kvm_vgic_global_state.nr_lr; count++)
+               vgic_clear_lr(vcpu, count);
+}
+
+/* Sync back the hardware VGIC state into our emulation after a guest's run. */
+void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
+{
+       vgic_process_maintenance_interrupt(vcpu);
+       vgic_fold_lr_state(vcpu);
+       vgic_prune_ap_list(vcpu);
+}
+
+/* Flush our emulation state into the GIC hardware before entering the guest. */
+void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
+{
+       spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
+       vgic_flush_lr_state(vcpu);
+       spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
+}

diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index c625767..29b96b9 100644 (file)
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -16,6 +16,8 @@
 #ifndef __KVM_ARM_VGIC_NEW_H__
 #define __KVM_ARM_VGIC_NEW_H__
 
+#define vgic_irq_is_sgi(intid) ((intid) < VGIC_NR_SGIS)
+
 struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
                              u32 intid);
 bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq);