KVM: arm/arm64: GICv4: Wire mapping/unmapping of VLPIs in VFIO irq by…

…pass

Let's use the irq bypass mechanism also used for x86 posted interrupts
to intercept the virtual PCIe endpoint configuration and establish our
LPI->VLPI mapping.

Reviewed-by: Christoffer Dall <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Signed-off-by: Christoffer Dall <[email protected]>

include/kvm/arm_vgic.h

@@ -373,4 +373,12 @@ int kvm_vgic_setup_default_irq_routing(struct kvm *kvm);
 
 int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner);
 
+struct kvm_kernel_irq_routing_entry;
+
+int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int irq,
+			       struct kvm_kernel_irq_routing_entry *irq_entry);
+
+int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq,
+				 struct kvm_kernel_irq_routing_entry *irq_entry);
+
 #endif /* __KVM_ARM_VGIC_H */

virt/kvm/arm/arm.c

@@ -1471,15 +1471,17 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
 	struct kvm_kernel_irqfd *irqfd =
 		container_of(cons, struct kvm_kernel_irqfd, consumer);
 
-	return 0;
+	return kvm_vgic_v4_set_forwarding(irqfd->kvm, prod->irq,
+					  &irqfd->irq_entry);
 }
 void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
 				      struct irq_bypass_producer *prod)
 {
 	struct kvm_kernel_irqfd *irqfd =
 		container_of(cons, struct kvm_kernel_irqfd, consumer);
 
-	return;
+	kvm_vgic_v4_unset_forwarding(irqfd->kvm, prod->irq,
+				     &irqfd->irq_entry);
 }
 
 void kvm_arch_irq_bypass_stop(struct irq_bypass_consumer *cons)

virt/kvm/arm/vgic/vgic-v4.c

@@ -18,6 +18,7 @@
 #include <linux/interrupt.h>
 #include <linux/irqdomain.h>
 #include <linux/kvm_host.h>
+#include <linux/irqchip/arm-gic-v3.h>
 
 #include "vgic.h"
 
@@ -81,3 +82,106 @@ void vgic_v4_teardown(struct kvm *kvm)
 	its_vm->nr_vpes = 0;
 	its_vm->vpes = NULL;
 }
+
+static struct vgic_its *vgic_get_its(struct kvm *kvm,
+				     struct kvm_kernel_irq_routing_entry *irq_entry)
+{
+	struct kvm_msi msi  = (struct kvm_msi) {
+		.address_lo	= irq_entry->msi.address_lo,
+		.address_hi	= irq_entry->msi.address_hi,
+		.data		= irq_entry->msi.data,
+		.flags		= irq_entry->msi.flags,
+		.devid		= irq_entry->msi.devid,
+	};
+
+	return vgic_msi_to_its(kvm, &msi);
+}
+
+int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq,
+			       struct kvm_kernel_irq_routing_entry *irq_entry)
+{
+	struct vgic_its *its;
+	struct vgic_irq *irq;
+	struct its_vlpi_map map;
+	int ret;
+
+	if (!vgic_supports_direct_msis(kvm))
+		return 0;
+
+	/*
+	 * Get the ITS, and escape early on error (not a valid
+	 * doorbell for any of our vITSs).
+	 */
+	its = vgic_get_its(kvm, irq_entry);
+	if (IS_ERR(its))
+		return 0;
+
+	mutex_lock(&its->its_lock);
+
+	/* Perform then actual DevID/EventID -> LPI translation. */
+	ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid,
+				   irq_entry->msi.data, &irq);
+	if (ret)
+		goto out;
+
+	/*
+	 * Emit the mapping request. If it fails, the ITS probably
+	 * isn't v4 compatible, so let's silently bail out. Holding
+	 * the ITS lock should ensure that nothing can modify the
+	 * target vcpu.
+	 */
+	map = (struct its_vlpi_map) {
+		.vm		= &kvm->arch.vgic.its_vm,
+		.vpe		= &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe,
+		.vintid		= irq->intid,
+		.properties	= ((irq->priority & 0xfc) |
+				   (irq->enabled ? LPI_PROP_ENABLED : 0) |
+				   LPI_PROP_GROUP1),
+		.db_enabled	= true,
+	};
+
+	ret = its_map_vlpi(virq, &map);
+	if (ret)
+		goto out;
+
+	irq->hw		= true;
+	irq->host_irq	= virq;
+
+out:
+	mutex_unlock(&its->its_lock);
+	return ret;
+}
+
+int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq,
+				 struct kvm_kernel_irq_routing_entry *irq_entry)
+{
+	struct vgic_its *its;
+	struct vgic_irq *irq;
+	int ret;
+
+	if (!vgic_supports_direct_msis(kvm))
+		return 0;
+
+	/*
+	 * Get the ITS, and escape early on error (not a valid
+	 * doorbell for any of our vITSs).
+	 */
+	its = vgic_get_its(kvm, irq_entry);
+	if (IS_ERR(its))
+		return 0;
+
+	mutex_lock(&its->its_lock);
+
+	ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid,
+				   irq_entry->msi.data, &irq);
+	if (ret)
+		goto out;
+
+	WARN_ON(!(irq->hw && irq->host_irq == virq));
+	irq->hw = false;
+	ret = its_unmap_vlpi(virq);
+
+out:
+	mutex_unlock(&its->its_lock);
+	return ret;
+}