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>

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 3199221..8dde369 100644 (file)
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1000,10 +1000,10 @@ long kvm_arch_vm_ioctl(struct file *filp,
                        goto out;
                if (irqchip_in_kernel(kvm)) {
                        __s32 status;
-                       mutex_lock(&kvm->lock);
+                       mutex_lock(&kvm->irq_lock);
                        status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
                                    irq_event.irq, irq_event.level);
-                       mutex_unlock(&kvm->lock);
+                       mutex_unlock(&kvm->irq_lock);
                        if (ioctl == KVM_IRQ_LINE_STATUS) {
                                irq_event.status = status;
                                if (copy_to_user(argp, &irq_event,

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 977af7a..3837db6 100644 (file)
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -654,10 +654,10 @@ static void __inject_pit_timer_intr(struct kvm *kvm)
        struct kvm_vcpu *vcpu;
        int i;
 
-       mutex_lock(&kvm->lock);
+       mutex_lock(&kvm->irq_lock);
        kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 1);
        kvm_set_irq(kvm, kvm->arch.vpit->irq_source_id, 0, 0);
-       mutex_unlock(&kvm->lock);
+       mutex_unlock(&kvm->irq_lock);
 
        /*
         * Provides NMI watchdog support via Virtual Wire mode.

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a23f42e..44f20cd 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -424,7 +424,9 @@ static void apic_set_eoi(struct kvm_lapic *apic)
                trigger_mode = IOAPIC_LEVEL_TRIG;
        else
                trigger_mode = IOAPIC_EDGE_TRIG;
+       mutex_lock(&apic->vcpu->kvm->irq_lock);
        kvm_ioapic_update_eoi(apic->vcpu->kvm, vector, trigger_mode);
+       mutex_unlock(&apic->vcpu->kvm->irq_lock);
 }
 
 static void apic_send_ipi(struct kvm_lapic *apic)
@@ -448,7 +450,9 @@ static void apic_send_ipi(struct kvm_lapic *apic)
                   irq.trig_mode, irq.level, irq.dest_mode, irq.delivery_mode,
                   irq.vector);
 
+       mutex_lock(&apic->vcpu->kvm->irq_lock);
        kvm_irq_delivery_to_apic(apic->vcpu->kvm, apic, &irq);
+       mutex_unlock(&apic->vcpu->kvm->irq_lock);
 }
 
 static u32 apic_get_tmcct(struct kvm_lapic *apic)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2ad8c97..05cbe83 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2136,10 +2136,10 @@ long kvm_arch_vm_ioctl(struct file *filp,
                        goto out;
                if (irqchip_in_kernel(kvm)) {
                        __s32 status;
-                       mutex_lock(&kvm->lock);
+                       mutex_lock(&kvm->irq_lock);
                        status = kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
                                        irq_event.irq, irq_event.level);
-                       mutex_unlock(&kvm->lock);
+                       mutex_unlock(&kvm->irq_lock);
                        if (ioctl == KVM_IRQ_LINE_STATUS) {
                                irq_event.status = status;
                                if (copy_to_user(argp, &irq_event,
@@ -2385,12 +2385,11 @@ mmio:
         */
        mutex_lock(&vcpu->kvm->lock);
        mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 0);
+       mutex_unlock(&vcpu->kvm->lock);
        if (mmio_dev) {
                kvm_iodevice_read(mmio_dev, gpa, bytes, val);
-               mutex_unlock(&vcpu->kvm->lock);
                return X86EMUL_CONTINUE;
        }
-       mutex_unlock(&vcpu->kvm->lock);
 
        vcpu->mmio_needed = 1;
        vcpu->mmio_phys_addr = gpa;
@@ -2440,12 +2439,11 @@ mmio:
         */
        mutex_lock(&vcpu->kvm->lock);
        mmio_dev = vcpu_find_mmio_dev(vcpu, gpa, bytes, 1);
+       mutex_unlock(&vcpu->kvm->lock);
        if (mmio_dev) {
                kvm_iodevice_write(mmio_dev, gpa, bytes, val);
-               mutex_unlock(&vcpu->kvm->lock);
                return X86EMUL_CONTINUE;
        }
-       mutex_unlock(&vcpu->kvm->lock);
 
        vcpu->mmio_needed = 1;
        vcpu->mmio_phys_addr = gpa;
@@ -2768,7 +2766,6 @@ static void kernel_pio(struct kvm_io_device *pio_dev,
 {
        /* TODO: String I/O for in kernel device */
 
-       mutex_lock(&vcpu->kvm->lock);
        if (vcpu->arch.pio.in)
                kvm_iodevice_read(pio_dev, vcpu->arch.pio.port,
                                  vcpu->arch.pio.size,
@@ -2777,7 +2774,6 @@ static void kernel_pio(struct kvm_io_device *pio_dev,
                kvm_iodevice_write(pio_dev, vcpu->arch.pio.port,
                                   vcpu->arch.pio.size,
                                   pd);
-       mutex_unlock(&vcpu->kvm->lock);
 }
 
 static void pio_string_write(struct kvm_io_device *pio_dev,
@@ -2787,14 +2783,12 @@ static void pio_string_write(struct kvm_io_device *pio_dev,
        void *pd = vcpu->arch.pio_data;
        int i;
 
-       mutex_lock(&vcpu->kvm->lock);
        for (i = 0; i < io->cur_count; i++) {
                kvm_iodevice_write(pio_dev, io->port,
                                   io->size,
                                   pd);
                pd += io->size;
        }
-       mutex_unlock(&vcpu->kvm->lock);
 }
 
 static struct kvm_io_device *vcpu_find_pio_dev(struct kvm_vcpu *vcpu,
@@ -2831,7 +2825,9 @@ int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
        val = kvm_register_read(vcpu, VCPU_REGS_RAX);
        memcpy(vcpu->arch.pio_data, &val, 4);
 
+       mutex_lock(&vcpu->kvm->lock);
        pio_dev = vcpu_find_pio_dev(vcpu, port, size, !in);
+       mutex_unlock(&vcpu->kvm->lock);
        if (pio_dev) {
                kernel_pio(pio_dev, vcpu, vcpu->arch.pio_data);
                complete_pio(vcpu);
@@ -2895,9 +2891,12 @@ int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
 
        vcpu->arch.pio.guest_gva = address;
 
+       mutex_lock(&vcpu->kvm->lock);
        pio_dev = vcpu_find_pio_dev(vcpu, port,
                                    vcpu->arch.pio.cur_count,
                                    !vcpu->arch.pio.in);
+       mutex_unlock(&vcpu->kvm->lock);
+
        if (!vcpu->arch.pio.in) {
                /* string PIO write */
                ret = pio_copy_data(vcpu);

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0c71688..a29ea03 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -371,7 +371,8 @@ int kvm_set_irq(struct kvm *kvm, int irq_source_id, int irq, int level);
 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);
-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);
 int kvm_request_irq_source_id(struct kvm *kvm);
 void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id);
 

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 3140123..4092b8d 100644 (file)
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -57,10 +57,10 @@ irqfd_inject(struct work_struct *work)
        struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
        struct kvm *kvm = irqfd->kvm;
 
-       mutex_lock(&kvm->lock);
+       mutex_lock(&kvm->irq_lock);
        kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
        kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
-       mutex_unlock(&kvm->lock);
+       mutex_unlock(&kvm->irq_lock);
 }
 
 /*

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index ddc17f0..08a9a49 100644 (file)
--- 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;
 

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d47e660..0d481b2 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -62,6 +62,12 @@
 MODULE_AUTHOR("Qumranet");
 MODULE_LICENSE("GPL");
 
+/*
+ * Ordering of locks:
+ *
+ *             kvm->lock --> kvm->irq_lock
+ */
+
 DEFINE_SPINLOCK(kvm_lock);
 LIST_HEAD(vm_list);
 
@@ -126,11 +132,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
                                    interrupt_work);
        kvm = assigned_dev->kvm;
 
-       /* This is taken to safely inject irq inside the guest. When
-        * the interrupt injection (or the ioapic code) uses a
-        * finer-grained lock, update this
-        */
-       mutex_lock(&kvm->lock);
+       mutex_lock(&kvm->irq_lock);
        spin_lock_irq(&assigned_dev->assigned_dev_lock);
        if (assigned_dev->irq_requested_type & KVM_DEV_IRQ_HOST_MSIX) {
                struct kvm_guest_msix_entry *guest_entries =
@@ -149,7 +151,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
                            assigned_dev->guest_irq, 1);
 
        spin_unlock_irq(&assigned_dev->assigned_dev_lock);
-       mutex_unlock(&assigned_dev->kvm->lock);
+       mutex_unlock(&assigned_dev->kvm->irq_lock);
 }
 
 static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
@@ -207,7 +209,7 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
 static void deassign_guest_irq(struct kvm *kvm,
                               struct kvm_assigned_dev_kernel *assigned_dev)
 {
-       kvm_unregister_irq_ack_notifier(&assigned_dev->ack_notifier);
+       kvm_unregister_irq_ack_notifier(kvm, &assigned_dev->ack_notifier);
        assigned_dev->ack_notifier.gsi = -1;
 
        if (assigned_dev->irq_source_id != -1)