[PATCH 06/10] KVM: arm/arm64: vgic: Allow dynamic mapping of physical/virtual interrupts

[Marc Zyngier]

In order to be able to feed physical interrupts to a guest, we need
to be able to establish the virtual-physical mapping between the two
worlds.

The mapping is kept in a rbtree, indexed by virtual interrupts.

Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 include/kvm/arm_vgic.h |  18 ++++++++
 virt/kvm/arm/vgic.c    | 110 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 128 insertions(+)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 4f9fa1d..33d121a 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -159,6 +159,14 @@ struct vgic_io_device {
 	struct kvm_io_device dev;
 };
 
+struct irq_phys_map {
+	struct rb_node		node;
+	u32			virt_irq;
+	u32			phys_irq;
+	u32			irq;
+	bool			active;
+};
+
 struct vgic_dist {
 	spinlock_t		lock;
 	bool			in_kernel;
@@ -256,6 +264,10 @@ struct vgic_dist {
 	struct vgic_vm_ops	vm_ops;
 	struct vgic_io_device	dist_iodev;
 	struct vgic_io_device	*redist_iodevs;
+
+	/* Virtual irq to hwirq mapping */
+	spinlock_t		irq_phys_map_lock;
+	struct rb_root		irq_phys_map;
 };
 
 struct vgic_v2_cpu_if {
@@ -307,6 +319,9 @@ struct vgic_cpu {
 		struct vgic_v2_cpu_if	vgic_v2;
 		struct vgic_v3_cpu_if	vgic_v3;
 	};
+
+	/* Protected by the distributor's irq_phys_map_lock */
+	struct rb_root	irq_phys_map;
 };
 
 #define LR_EMPTY	0xff
@@ -331,6 +346,9 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
 void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg);
 int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
 int kvm_vgic_vcpu_active_irq(struct kvm_vcpu *vcpu);
+struct irq_phys_map *vgic_map_phys_irq(struct kvm_vcpu *vcpu,
+				       int virt_irq, int irq);
+int vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, struct irq_phys_map *map);
 
 #define irqchip_in_kernel(k)	(!!((k)->arch.vgic.in_kernel))
 #define vgic_initialized(k)	(!!((k)->arch.vgic.nr_cpus))
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 59ed7a3..c6604f2 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -24,6 +24,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
+#include <linux/rbtree.h>
 #include <linux/uaccess.h>
 
 #include <linux/irqchip/arm-gic.h>
@@ -84,6 +85,8 @@ static void vgic_retire_disabled_irqs(struct kvm_vcpu *vcpu);
 static void vgic_retire_lr(int lr_nr, int irq, struct kvm_vcpu *vcpu);
 static struct vgic_lr vgic_get_lr(const struct kvm_vcpu *vcpu, int lr);
 static void vgic_set_lr(struct kvm_vcpu *vcpu, int lr, struct vgic_lr lr_desc);
+static struct irq_phys_map *vgic_irq_map_search(struct kvm_vcpu *vcpu,
+						int virt_irq);
 
 static const struct vgic_ops *vgic_ops;
 static const struct vgic_params *vgic;
@@ -1585,6 +1588,112 @@ static irqreturn_t vgic_maintenance_handler(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+static struct rb_root *vgic_get_irq_phys_map(struct kvm_vcpu *vcpu,
+					     int virt_irq)
+{
+	if (virt_irq < VGIC_NR_PRIVATE_IRQS)
+		return &vcpu->arch.vgic_cpu.irq_phys_map;
+	else
+		return &vcpu->kvm->arch.vgic.irq_phys_map;
+}
+
+struct irq_phys_map *vgic_map_phys_irq(struct kvm_vcpu *vcpu,
+				       int virt_irq, int irq)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+	struct rb_root *root = vgic_get_irq_phys_map(vcpu, virt_irq);
+	struct rb_node **new = &root->rb_node, *parent = NULL;
+	struct irq_phys_map *new_map;
+	struct irq_desc *desc;
+	struct irq_data *data;
+	int phys_irq;
+
+	desc = irq_to_desc(irq);
+	if (!desc) {
+		kvm_err("kvm_arch_timer: can't obtain interrupt descriptor\n");
+		return NULL;
+	}
+
+	data = irq_desc_get_irq_data(desc);
+	while (data->parent_data)
+		data = data->parent_data;
+
+	phys_irq = data->hwirq;
+
+	spin_lock(&dist->irq_phys_map_lock);
+
+	/* Boilerplate rb_tree code */
+	while (*new) {
+		struct irq_phys_map *this;
+
+		this = container_of(*new, struct irq_phys_map, node);
+		parent = *new;
+		if (this->virt_irq < virt_irq)
+			new = &(*new)->rb_left;
+		else if (this->virt_irq > virt_irq)
+			new = &(*new)->rb_right;
+		else {
+			new_map = this;
+			goto out;
+		}
+	}
+
+	new_map = kzalloc(sizeof(*new_map), GFP_KERNEL);
+	if (!new_map)
+		goto out;
+
+	new_map->virt_irq = virt_irq;
+	new_map->phys_irq = phys_irq;
+	new_map->irq = irq;
+
+	rb_link_node(&new_map->node, parent, new);
+	rb_insert_color(&new_map->node, root);
+
+out:
+	spin_unlock(&dist->irq_phys_map_lock);
+	return new_map;
+}
+
+static struct irq_phys_map *vgic_irq_map_search(struct kvm_vcpu *vcpu,
+						int virt_irq)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+	struct rb_root *root = vgic_get_irq_phys_map(vcpu, virt_irq);
+	struct rb_node *node = root->rb_node;
+	struct irq_phys_map *this = NULL;
+
+	spin_lock(&dist->irq_phys_map_lock);
+
+	while (node) {
+		this = container_of(node, struct irq_phys_map, node);
+
+		if (this->virt_irq < virt_irq)
+			node = node->rb_left;
+		else if (this->virt_irq > virt_irq)
+			node = node->rb_right;
+		else
+			break;
+	}
+
+	spin_unlock(&dist->irq_phys_map_lock);
+	return this;
+}
+
+int vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, struct irq_phys_map *map)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+	if (!map)
+		return -EINVAL;
+
+	spin_lock(&dist->irq_phys_map_lock);
+	rb_erase(&map->node, vgic_get_irq_phys_map(vcpu, map->virt_irq));
+	spin_unlock(&dist->irq_phys_map_lock);
+
+	kfree(map);
+	return 0;
+}
+
 void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
@@ -1835,6 +1944,7 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
 		goto out_unlock;
 
 	spin_lock_init(&kvm->arch.vgic.lock);
+	spin_lock_init(&kvm->arch.vgic.irq_phys_map_lock);
 	kvm->arch.vgic.in_kernel = true;
 	kvm->arch.vgic.vgic_model = type;
 	kvm->arch.vgic.vctrl_base = vgic->vctrl_base;
-- 
2.1.4