KVM: Fix assigned devices circular locking dependency

[safe/jmp/linux-2.6] / virt / kvm / kvm_main.c

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3a5a082..29a667c 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -173,7 +173,6 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work)
                assigned_dev->host_irq_disabled = false;
        }
        mutex_unlock(&assigned_dev->kvm->lock);
-       kvm_put_kvm(assigned_dev->kvm);
 }
 
 static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
@@ -181,8 +180,6 @@ static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id)
        struct kvm_assigned_dev_kernel *assigned_dev =
                (struct kvm_assigned_dev_kernel *) dev_id;
 
-       kvm_get_kvm(assigned_dev->kvm);
-
        schedule_work(&assigned_dev->interrupt_work);
 
        disable_irq_nosync(irq);
@@ -213,6 +210,7 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian)
        }
 }
 
+/* The function implicit hold kvm->lock mutex due to cancel_work_sync() */
 static void kvm_free_assigned_irq(struct kvm *kvm,
                                  struct kvm_assigned_dev_kernel *assigned_dev)
 {
@@ -228,11 +226,24 @@ static void kvm_free_assigned_irq(struct kvm *kvm,
        if (!assigned_dev->irq_requested_type)
                return;
 
-       if (cancel_work_sync(&assigned_dev->interrupt_work))
-               /* We had pending work. That means we will have to take
-                * care of kvm_put_kvm.
-                */
-               kvm_put_kvm(kvm);
+       /*
+        * In kvm_free_device_irq, cancel_work_sync return true if:
+        * 1. work is scheduled, and then cancelled.
+        * 2. work callback is executed.
+        *
+        * The first one ensured that the irq is disabled and no more events
+        * would happen. But for the second one, the irq may be enabled (e.g.
+        * for MSI). So we disable irq here to prevent further events.
+        *
+        * Notice this maybe result in nested disable if the interrupt type is
+        * INTx, but it's OK for we are going to free it.
+        *
+        * If this function is a part of VM destroy, please ensure that till
+        * now, the kvm state is still legal for probably we also have to wait
+        * interrupt_work done.
+        */
+       disable_irq_nosync(assigned_dev->host_irq);
+       cancel_work_sync(&assigned_dev->interrupt_work);
 
        free_irq(assigned_dev->host_irq, (void *)assigned_dev);
 
@@ -285,8 +296,8 @@ static int assigned_device_update_intx(struct kvm *kvm,
 
        if (irqchip_in_kernel(kvm)) {
                if (!msi2intx &&
-                   adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI) {
-                       free_irq(adev->host_irq, (void *)kvm);
+                   (adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI)) {
+                       free_irq(adev->host_irq, (void *)adev);
                        pci_disable_msi(adev->dev);
                }
 
@@ -455,6 +466,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
        struct kvm_assigned_dev_kernel *match;
        struct pci_dev *dev;
 
+       down_read(&kvm->slots_lock);
        mutex_lock(&kvm->lock);
 
        match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
@@ -516,6 +528,7 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 
 out:
        mutex_unlock(&kvm->lock);
+       up_read(&kvm->slots_lock);
        return r;
 out_list_del:
        list_del(&match->list);
@@ -527,6 +540,7 @@ out_put:
 out_free:
        kfree(match);
        mutex_unlock(&kvm->lock);
+       up_read(&kvm->slots_lock);
        return r;
 }
 #endif
@@ -789,11 +803,19 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
        return young;
 }
 
+static void kvm_mmu_notifier_release(struct mmu_notifier *mn,
+                                    struct mm_struct *mm)
+{
+       struct kvm *kvm = mmu_notifier_to_kvm(mn);
+       kvm_arch_flush_shadow(kvm);
+}
+
 static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
        .invalidate_page        = kvm_mmu_notifier_invalidate_page,
        .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start,
        .invalidate_range_end   = kvm_mmu_notifier_invalidate_range_end,
        .clear_flush_young      = kvm_mmu_notifier_clear_flush_young,
+       .release                = kvm_mmu_notifier_release,
 };
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
 
@@ -883,6 +905,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
 {
        struct mm_struct *mm = kvm->mm;
 
+       kvm_arch_sync_events(kvm);
        spin_lock(&kvm_lock);
        list_del(&kvm->vm_list);
        spin_unlock(&kvm_lock);