KVM: Fix assigned devices circular locking dependency
Mark McLoughlin [Thu, 5 Feb 2009 18:23:46 +0000 (18:23 +0000)]
kvm->slots_lock is outer to kvm->lock, so take slots_lock
in kvm_vm_ioctl_assign_device() before taking kvm->lock,
rather than taking it in kvm_iommu_map_memslots().

Cc: stable@kernel.org
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

virt/kvm/iommu.c
virt/kvm/kvm_main.c

index e9693a2..4c40375 100644 (file)
@@ -73,14 +73,13 @@ static int kvm_iommu_map_memslots(struct kvm *kvm)
 {
        int i, r = 0;
 
-       down_read(&kvm->slots_lock);
        for (i = 0; i < kvm->nmemslots; i++) {
                r = kvm_iommu_map_pages(kvm, kvm->memslots[i].base_gfn,
                                        kvm->memslots[i].npages);
                if (r)
                        break;
        }
-       up_read(&kvm->slots_lock);
+
        return r;
 }
 
@@ -190,12 +189,11 @@ static void kvm_iommu_put_pages(struct kvm *kvm,
 static int kvm_iommu_unmap_memslots(struct kvm *kvm)
 {
        int i;
-       down_read(&kvm->slots_lock);
+
        for (i = 0; i < kvm->nmemslots; i++) {
                kvm_iommu_put_pages(kvm, kvm->memslots[i].base_gfn,
                                    kvm->memslots[i].npages);
        }
-       up_read(&kvm->slots_lock);
 
        return 0;
 }
index d9bbb20..29a667c 100644 (file)
@@ -466,6 +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,
@@ -527,6 +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);
@@ -538,6 +540,7 @@ out_put:
 out_free:
        kfree(match);
        mutex_unlock(&kvm->lock);
+       up_read(&kvm->slots_lock);
        return r;
 }
 #endif