KVM: Fix possible circular locking in kvm_vm_ioctl_assign_device() (fae3a353) · Commits · 戴 / test

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>

virt/kvm/assigned-dev.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -508,8 +508,8 @@ 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);
		down_read(&kvm->slots_lock);

		match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
		assigned_dev->assigned_dev_id);
		@@ -573,8 +573,8 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
		}

		out:
		mutex_unlock(&kvm->lock);
		up_read(&kvm->slots_lock);
		mutex_unlock(&kvm->lock);
		return r;
		out_list_del:
		list_del(&match->list);
		@@ -585,8 +585,8 @@ out_put:
		pci_dev_put(dev);
		out_free:
		kfree(match);
		mutex_unlock(&kvm->lock);
		up_read(&kvm->slots_lock);
		mutex_unlock(&kvm->lock);
		return r;
		}

virt/kvm/kvm_main.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -64,7 +64,7 @@ MODULE_LICENSE("GPL");
		/*
		* Ordering of locks:
		*
		* kvm->slots_lock --> kvm->lock --> kvm->irq_lock
		* kvm->lock --> kvm->slots_lock --> kvm->irq_lock
		*/

		DEFINE_SPINLOCK(kvm_lock);

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