This is to avoid a circular refcount problem between the kvm struct and
the device file. KVM modules holds device/group file reference when the
device/group is added and releases it per removal or the last kvm reference
is released. This reference model is ok for the group since there is no
kvm reference in the group paths.
But it is a problem for device file since the vfio devices may get kvm
reference in the device open path and put it in the device file release.
e.g. Intel kvmgt. This would result in a circular issue since the kvm
side won't put the device file reference if kvm reference is not 0, while
the vfio device side needs to put kvm reference in the release callback.
To solve this problem for device file, let vfio provide release() which
would be called once kvm file is closed, it won't depend on the last kvm
reference. Hence avoid circular refcount problem.
Suggested-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
virt/kvm/vfio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 0f54b9d308d7..525efe37ab6d 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -364,7 +364,7 @@ static int kvm_vfio_create(struct kvm_device *dev, u32 type);
static struct kvm_device_ops kvm_vfio_ops = {
.name = "kvm-vfio",
.create = kvm_vfio_create,
- .destroy = kvm_vfio_destroy,
+ .release = kvm_vfio_destroy,
.set_attr = kvm_vfio_set_attr,
.has_attr = kvm_vfio_has_attr,
};
--
2.34.1
