KVM: switch irq injection/acking data structures to irq_lock

Protect irq injection/acking data structures with a separate irq_lock
mutex. This fixes the following deadlock:

CPU A                               CPU B
kvm_vm_ioctl_deassign_dev_irq()
  mutex_lock(&kvm->lock);            worker_thread()
  -> kvm_deassign_irq()                -> kvm_assigned_dev_interrupt_work_handler()
    -> deassign_host_irq()               mutex_lock(&kvm->lock);
      -> cancel_work_sync() [blocked]

[gleb: fix ia64 path]

Reported-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 28 insertions, 6 deletions

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index ddc17f0e2f3..08a9a49481b 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -62,6 +62,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 	int i, r = -1;
 	struct kvm_vcpu *vcpu, *lowest = NULL;
 
+	WARN_ON(!mutex_is_locked(&kvm->irq_lock));
+
 	if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
 			kvm_is_dm_lowest_prio(irq))
 		printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
@@ -113,7 +115,7 @@ static int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
 	return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
 }
 
-/* This should be called with the kvm->lock mutex held
+/* This should be called with the kvm->irq_lock mutex held
  * Return value:
  *  < 0   Interrupt was ignored (masked or not delivered for other reasons)
  *  = 0   Interrupt was coalesced (previous irq is still pending)
@@ -125,6 +127,8 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level)
 	unsigned long *irq_state, sig_level;
 	int ret = -1;
 
+	WARN_ON(!mutex_is_locked(&kvm->irq_lock));
+
 	if (irq < KVM_IOAPIC_NUM_PINS) {
 		irq_state = (unsigned long *)&kvm->arch.irq_states[irq];
 
@@ -175,19 +179,26 @@ void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 void kvm_register_irq_ack_notifier(struct kvm *kvm,
 				   struct kvm_irq_ack_notifier *kian)
 {
+	mutex_lock(&kvm->irq_lock);
 	hlist_add_head(&kian->link, &kvm->arch.irq_ack_notifier_list);
+	mutex_unlock(&kvm->irq_lock);
 }
 
-void kvm_unregister_irq_ack_notifier(struct kvm_irq_ack_notifier *kian)
+void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
+				    struct kvm_irq_ack_notifier *kian)
 {
+	mutex_lock(&kvm->irq_lock);
 	hlist_del_init(&kian->link);
+	mutex_unlock(&kvm->irq_lock);
 }
 
-/* The caller must hold kvm->lock mutex */
 int kvm_request_irq_source_id(struct kvm *kvm)
 {
 	unsigned long *bitmap = &kvm->arch.irq_sources_bitmap;
-	int irq_source_id = find_first_zero_bit(bitmap,
+	int irq_source_id;
+
+	mutex_lock(&kvm->irq_lock);
+	irq_source_id = find_first_zero_bit(bitmap,
 				sizeof(kvm->arch.irq_sources_bitmap));
 
 	if (irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
@@ -197,6 +208,7 @@ int kvm_request_irq_source_id(struct kvm *kvm)
 
 	ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
 	set_bit(irq_source_id, bitmap);
+	mutex_unlock(&kvm->irq_lock);
 
 	return irq_source_id;
 }
@@ -207,6 +219,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
 
 	ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
 
+	mutex_lock(&kvm->irq_lock);
 	if (irq_source_id < 0 ||
 	    irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
 		printk(KERN_ERR "kvm: IRQ source ID out of range!\n");
@@ -215,19 +228,24 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
 	for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
 		clear_bit(irq_source_id, &kvm->arch.irq_states[i]);
 	clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
+	mutex_unlock(&kvm->irq_lock);
 }
 
 void kvm_register_irq_mask_notifier(struct kvm *kvm, int irq,
 				    struct kvm_irq_mask_notifier *kimn)
 {
+	mutex_lock(&kvm->irq_lock);
 	kimn->irq = irq;
 	hlist_add_head(&kimn->link, &kvm->mask_notifier_list);
+	mutex_unlock(&kvm->irq_lock);
 }
 
 void kvm_unregister_irq_mask_notifier(struct kvm *kvm, int irq,
 				      struct kvm_irq_mask_notifier *kimn)
 {
+	mutex_lock(&kvm->irq_lock);
 	hlist_del(&kimn->link);
+	mutex_unlock(&kvm->irq_lock);
 }
 
 void kvm_fire_mask_notifiers(struct kvm *kvm, int irq, bool mask)
@@ -235,6 +253,8 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, int irq, bool mask)
 	struct kvm_irq_mask_notifier *kimn;
 	struct hlist_node *n;
 
+	WARN_ON(!mutex_is_locked(&kvm->irq_lock));
+
 	hlist_for_each_entry(kimn, n, &kvm->mask_notifier_list, link)
 		if (kimn->irq == irq)
 			kimn->func(kimn, mask);
@@ -250,7 +270,9 @@ static void __kvm_free_irq_routing(struct list_head *irq_routing)
 
 void kvm_free_irq_routing(struct kvm *kvm)
 {
+	mutex_lock(&kvm->irq_lock);
 	__kvm_free_irq_routing(&kvm->irq_routing);
+	mutex_unlock(&kvm->irq_lock);
 }
 
 static int setup_routing_entry(struct kvm_kernel_irq_routing_entry *e,
@@ -325,13 +347,13 @@ int kvm_set_irq_routing(struct kvm *kvm,
 		e = NULL;
 	}
 
-	mutex_lock(&kvm->lock);
+	mutex_lock(&kvm->irq_lock);
 	list_splice(&kvm->irq_routing, &tmp);
 	INIT_LIST_HEAD(&kvm->irq_routing);
 	list_splice(&irq_list, &kvm->irq_routing);
 	INIT_LIST_HEAD(&irq_list);
 	list_splice(&tmp, &irq_list);
-	mutex_unlock(&kvm->lock);
+	mutex_unlock(&kvm->irq_lock);
 
 	r = 0;