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KVM: Fix possible circular locking in kvm_vm_ioctl_assign_device()
One possible order is: KVM_CREATE_IRQCHIP ioctl(took kvm->lock) -> kvm_iobus_register_dev() -> down_write(kvm->slots_lock). The other one is in kvm_vm_ioctl_assign_device(), which take kvm->slots_lock first, then kvm->lock. Update the comment of lock order as well. Observe it due to kernel locking debug warnings. Cc: stable@kernel.org Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
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parent
fb341f572d
commit
fae3a3536a
2 changed files with 4 additions and 4 deletions
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@ -508,8 +508,8 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
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struct kvm_assigned_dev_kernel *match;
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struct kvm_assigned_dev_kernel *match;
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struct pci_dev *dev;
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struct pci_dev *dev;
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down_read(&kvm->slots_lock);
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mutex_lock(&kvm->lock);
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mutex_lock(&kvm->lock);
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down_read(&kvm->slots_lock);
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match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
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match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
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assigned_dev->assigned_dev_id);
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assigned_dev->assigned_dev_id);
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@ -573,8 +573,8 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
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}
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}
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out:
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out:
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mutex_unlock(&kvm->lock);
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up_read(&kvm->slots_lock);
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up_read(&kvm->slots_lock);
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mutex_unlock(&kvm->lock);
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return r;
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return r;
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out_list_del:
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out_list_del:
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list_del(&match->list);
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list_del(&match->list);
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@ -585,8 +585,8 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
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pci_dev_put(dev);
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pci_dev_put(dev);
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out_free:
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out_free:
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kfree(match);
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kfree(match);
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mutex_unlock(&kvm->lock);
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up_read(&kvm->slots_lock);
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up_read(&kvm->slots_lock);
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mutex_unlock(&kvm->lock);
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return r;
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return r;
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}
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}
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@ -64,7 +64,7 @@ MODULE_LICENSE("GPL");
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/*
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/*
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* Ordering of locks:
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* Ordering of locks:
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*
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*
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* kvm->slots_lock --> kvm->lock --> kvm->irq_lock
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* kvm->lock --> kvm->slots_lock --> kvm->irq_lock
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*/
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*/
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DEFINE_SPINLOCK(kvm_lock);
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DEFINE_SPINLOCK(kvm_lock);
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