[RFC 2/9] KVM: ARM: VGIC: add forwarded irq rbtree lock

Eric Auger
2014-08-25T13:28:48Z

add a lock related to the rb tree manipulation. The rb tree can be
searched in one thread (irqfd handler for instance) and map/unmap
happen in another.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
---
virt/kvm/arm/vgic.c | 46 +++++++++++++++++++++++++++++++++++++---------
1 file changed, 37 insertions(+), 9 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 195c10c..3311e0a 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1628,9 +1628,15 @@ static struct rb_root *vgic_get_irq_phys_map(struct kvm_vcpu *vcpu,

int vgic_map_phys_irq(struct kvm_vcpu *vcpu, int virt_irq, int phys_irq)
{
- struct rb_root *root = vgic_get_irq_phys_map(vcpu, virt_irq);
- struct rb_node **new = &root->rb_node, *parent = NULL;
+ struct rb_root *root;
+ struct rb_node **new, *parent = NULL;
struct irq_phys_map *new_map;
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ spin_lock(&dist->rb_tree_lock);
+
+ root = vgic_get_irq_phys_map(vcpu, virt_irq);
+ new = &root->rb_node;

/* Boilerplate rb_tree code */
while (*new) {
@@ -1642,13 +1648,17 @@ int vgic_map_phys_irq(struct kvm_vcpu *vcpu, int virt_irq, int phys_irq)
new = &(*new)->rb_left;
else if (this->virt_irq > virt_irq)
new = &(*new)->rb_right;
- else
+ else {
+ spin_unlock(&dist->rb_tree_lock);
return -EEXIST;
+ }
}

new_map = kzalloc(sizeof(*new_map), GFP_KERNEL);
- if (!new_map)
+ if (!new_map) {
+ spin_unlock(&dist->rb_tree_lock);
return -ENOMEM;
+ }

new_map->virt_irq = virt_irq;
new_map->phys_irq = phys_irq;
@@ -1656,6 +1666,8 @@ int vgic_map_phys_irq(struct kvm_vcpu *vcpu, int virt_irq, int phys_irq)
rb_link_node(&new_map->node, parent, new);
rb_insert_color(&new_map->node, root);

+ spin_unlock(&dist->rb_tree_lock);
+
return 0;
}

@@ -1683,24 +1695,39 @@ static struct irq_phys_map *vgic_irq_map_search(struct kvm_vcpu *vcpu,

int vgic_get_phys_irq(struct kvm_vcpu *vcpu, int virt_irq)
{
- struct irq_phys_map *map = vgic_irq_map_search(vcpu, virt_irq);
+ struct irq_phys_map *map;
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+ int ret;
+
+ spin_lock(&dist->rb_tree_lock);
+ map = vgic_irq_map_search(vcpu, virt_irq);

if (map)
- return map->phys_irq;
+ ret = map->phys_irq;
+ else
+ ret = -ENOENT;
+
+ spin_unlock(&dist->rb_tree_lock);
+ return ret;

- return -ENOENT;
}

int vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, int virt_irq, int phys_irq)
{
- struct irq_phys_map *map = vgic_irq_map_search(vcpu, virt_irq);
+ struct irq_phys_map *map;
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ spin_lock(&dist->rb_tree_lock);
+
+ map = vgic_irq_map_search(vcpu, virt_irq);

if (map && map->phys_irq == phys_irq) {
rb_erase(&map->node, vgic_get_irq_phys_map(vcpu, virt_irq));
kfree(map);
+ spin_unlock(&dist->rb_tree_lock);
return 0;
}
-
+ spin_unlock(&dist->rb_tree_lock);
return -ENOENT;
}

@@ -1896,6 +1923,7 @@ int kvm_vgic_create(struct kvm *kvm)
}

spin_lock_init(&kvm->arch.vgic.lock);
+ spin_lock_init(&kvm->arch.vgic.rb_tree_lock);
kvm->arch.vgic.in_kernel = true;
kvm->arch.vgic.vctrl_base = vgic->vctrl_base;
kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF;
--
1.9.1