Re: [Intel-gfx] [PATCH v2 07/11] vfio-iommufd: Support iommufd for physical VFIO devices

[Yi Liu]

On 2022/11/8 14:10, Nicolin Chen wrote:

On Mon, Nov 07, 2022 at 08:52:51PM -0400, Jason Gunthorpe wrote:

@@ -795,6 +800,10 @@ static int vfio_device_first_open(struct vfio_device 
*device)
                ret = vfio_group_use_container(device->group);
                if (ret)
                        goto err_module_put;
+       } else if (device->group->iommufd) {
+               ret = vfio_iommufd_bind(device, device->group->iommufd);

Here we check device->group->iommufd...

+               if (ret)
+                       goto err_module_put;
        }

device->kvm = device->group->kvm;

@@ -812,6 +821,7 @@ static int vfio_device_first_open(struct vfio_device 
*device)
        device->kvm = NULL;
        if (device->group->container)
                vfio_group_unuse_container(device->group);
+       vfio_iommufd_unbind(device);

...yet, missing here, which could result in kernel oops.

Should probably add something similar:
+       if (device->group->iommufd)
+               vfio_iommufd_unbind(device);

Or should check !vdev->iommufd_device inside the ->unbind.

this check was in prior version, but removed in this version. any
special reason? Jason?

  err_module_put:
        mutex_unlock(&device->group->group_lock);
        module_put(device->dev->driver->owner);
@@ -830,6 +840,7 @@ static void vfio_device_last_close(struct vfio_device 
*device)
        device->kvm = NULL;
        if (device->group->container)
                vfio_group_unuse_container(device->group);
+       vfio_iommufd_unbind(device);

Ditto

--
Regards,
Yi Liu