[PATCH 08/45] KVM: arm/arm64: vgic-new: Add IRQ sync/flush framework
Andre Przywara
andre.przywara at arm.com
Fri Apr 15 10:11:19 PDT 2016
From: Marc Zyngier <marc.zyngier at arm.com>
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 at arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
Signed-off-by: Eric Auger <eric.auger at linaro.org>
Signed-off-by: Andre Przywara <andre.przywara at arm.com>
Changelog RFC..v1:
- split out vgic_clear_lr() from vgic_populate_lr()
- rename vgic_populate_lrs() to vgic_flush_lr_state()
- clean all LRs when the distributor is disabled
- use list_del() instead of list_del_init()
- add comments to explain the direction of sync/flush_hwstate
- remove unneeded BUG_ON(in_interrupt()
---
include/kvm/vgic/vgic.h | 4 +
virt/kvm/arm/vgic/vgic.c | 200 +++++++++++++++++++++++++++++++++++++++++++++++
virt/kvm/arm/vgic/vgic.h | 2 +
3 files changed, 206 insertions(+)
diff --git a/include/kvm/vgic/vgic.h b/include/kvm/vgic/vgic.h
index dd884ba..97c919c 100644
--- 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 0b1dadf..65fa9ac 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -293,3 +293,203 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
vgic_update_irq_pending(kvm, vcpu, intid, level);
return 0;
}
+
+/**
+ * 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(&vcpuB->arch.vgic_cpu.ap_list_lock);
+ 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 ap_list_lock and 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(&vcpu->arch.vgic_cpu.ap_list_lock));
+ 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)
+{
+}
+
+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;
+
+ 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_dist *dist = &vcpu->kvm->arch.vgic;
+ u32 model = dist->vgic_model;
+ struct vgic_irq *irq;
+ int count = 0;
+
+ DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(vgic_cpu->ap_list_lock));
+
+ if (unlikely(!dist->enabled))
+ goto out_clean;
+
+ 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.
+ */
+ if (model == KVM_DEV_TYPE_ARM_VGIC_V2 &&
+ vgic_irq_is_sgi(irq->intid)) {
+ while (irq->source &&
+ count < kvm_vgic_global_state.nr_lr)
+ vgic_populate_lr(vcpu, irq, count++);
+ } else {
+ vgic_populate_lr(vcpu, irq, count++);
+ }
+
+next:
+ spin_unlock(&irq->irq_lock);
+
+ if (count == kvm_vgic_global_state.nr_lr)
+ break;
+ }
+
+out_clean:
+ 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
--- 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);
--
2.7.3
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