Commit 5ea5ca3c authored by Wei Wang's avatar Wei Wang Committed by Sean Christopherson
Browse files

KVM: destruct kvm_io_device while unregistering it from kvm_io_bus 



Current usage of kvm_io_device requires users to destruct it with an extra
call of kvm_iodevice_destructor after the device gets unregistered from
kvm_io_bus. This is not necessary and can cause errors if a user forgot
to make the extra call.

Simplify the usage by combining kvm_iodevice_destructor into
kvm_io_bus_unregister_dev. This reduces LOCs a bit for users and can
avoid the leakage of destructing the device explicitly.

Signed-off-by: default avatarWei Wang <wei.w.wang@intel.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20230207123713.3905-2-wei.w.wang@intel.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 5f643e46

include/kvm/iodev.h

+0 −6
Original line number Diff line number Diff line
@@ -55,10 +55,4 @@ static inline int kvm_iodevice_write(struct kvm_vcpu *vcpu, 
				 : -EOPNOTSUPP;

}



static inline void kvm_iodevice_destructor(struct kvm_io_device *dev)

{

	if (dev->ops->destructor)

		dev->ops->destructor(dev);

}



#endif /* __KVM_IODEV_H__ */

virt/kvm/coalesced_mmio.c

+2 −7
Original line number Diff line number Diff line
@@ -186,15 +186,10 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, 
		    coalesced_mmio_in_range(dev, zone->addr, zone->size)) {

			r = kvm_io_bus_unregister_dev(kvm,

				zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev);



			kvm_iodevice_destructor(&dev->dev);



			/*

			 * On failure, unregister destroys all devices on the

			 * bus _except_ the target device, i.e. coalesced_zones

			 * has been modified.  Bail after destroying the target

			 * device, there's no need to restart the walk as there

			 * aren't any zones left.

			 * bus, including the target device. There's no need

			 * to restart the walk as there aren't any zones left.

			 */

			if (r)

				break;

virt/kvm/eventfd.c

+0 −1
Original line number Diff line number Diff line
@@ -931,7 +931,6 @@ kvm_deassign_ioeventfd_idx(struct kvm *kvm, enum kvm_bus bus_idx, 
		bus = kvm_get_bus(kvm, bus_idx);

		if (bus)

			bus->ioeventfd_count--;

		ioeventfd_release(p);

		ret = 0;

		break;

	}

virt/kvm/kvm_main.c

+15 −8
Original line number Diff line number Diff line
@@ -5297,6 +5297,12 @@ static void hardware_disable_all(void) 
}

#endif /* CONFIG_KVM_GENERIC_HARDWARE_ENABLING */



static void kvm_iodevice_destructor(struct kvm_io_device *dev)

{

	if (dev->ops->destructor)

		dev->ops->destructor(dev);

}



static void kvm_io_bus_destroy(struct kvm_io_bus *bus)

{

	int i;
@@ -5520,7 +5526,7 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, 
int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,

			      struct kvm_io_device *dev)

{

	int i, j;

	int i;

	struct kvm_io_bus *new_bus, *bus;



	lockdep_assert_held(&kvm->slots_lock);
@@ -5550,18 +5556,19 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, 
	rcu_assign_pointer(kvm->buses[bus_idx], new_bus);

	synchronize_srcu_expedited(&kvm->srcu);



	/* Destroy the old bus _after_ installing the (null) bus. */

	/*

	 * If NULL bus is installed, destroy the old bus, including all the

	 * attached devices. Otherwise, destroy the caller's device only.

	 */

	if (!new_bus) {

		pr_err("kvm: failed to shrink bus, removing it completely\n");

		for (j = 0; j < bus->dev_count; j++) {

			if (j == i)

				continue;

			kvm_iodevice_destructor(bus->range[j].dev);

		}

		kvm_io_bus_destroy(bus);

		return -ENOMEM;

	}



	kvm_iodevice_destructor(dev);

	kfree(bus);

	return new_bus ? 0 : -ENOMEM;

	return 0;

}



struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,