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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: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20230207123713.3905-2-wei.w.wang@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Wei Wang 2023-02-07 20:37:12 +08:00 committed by Sean Christopherson
parent 5f643e460a
commit 5ea5ca3c2b
4 changed files with 17 additions and 22 deletions
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6
include/kvm/iodev.h
View File

@ -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__ */

9
virt/kvm/coalesced_mmio.c
View File

@ -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;

1
virt/kvm/eventfd.c
View File

@ -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;
}

23
virt/kvm/kvm_main.c
View File

@ -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,