Hi Yi,
On 4/1/23 17:18, Yi Liu wrote:
> for counting the devices that are opened via the cdev path. This count
> is increased and decreased by the cdev path. The group path checks it
> to achieve exclusion with the cdev path. With this, only one path (group
> path or cdev path) will claim DMA ownership. This avoids scenarios in
> which devices within the same group may be opened via different paths.
>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Tested-by: Terrence Xu <terrence.xu@xxxxxxxxx>
> Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Tested-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
> Tested-by: Yanting Jiang <yanting.jiang@xxxxxxxxx>
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Thanks
Eric
> ---
> drivers/vfio/group.c | 33 +++++++++++++++++++++++++++++++++
> drivers/vfio/vfio.h | 3 +++
> 2 files changed, 36 insertions(+)
>
> diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
> index 71f0a9a4016e..d55ce3ca44b7 100644
> --- a/drivers/vfio/group.c
> +++ b/drivers/vfio/group.c
> @@ -383,6 +383,33 @@ static long vfio_group_fops_unl_ioctl(struct file *filep,
> }
> }
>
> +int vfio_device_block_group(struct vfio_device *device)
> +{
> + struct vfio_group *group = device->group;
> + int ret = 0;
> +
> + mutex_lock(&group->group_lock);
> + if (group->opened_file) {
> + ret = -EBUSY;
> + goto out_unlock;
> + }
> +
> + group->cdev_device_open_cnt++;
> +
> +out_unlock:
> + mutex_unlock(&group->group_lock);
> + return ret;
> +}
> +
> +void vfio_device_unblock_group(struct vfio_device *device)
> +{
> + struct vfio_group *group = device->group;
> +
> + mutex_lock(&group->group_lock);
> + group->cdev_device_open_cnt--;
> + mutex_unlock(&group->group_lock);
> +}
> +
> static int vfio_group_fops_open(struct inode *inode, struct file *filep)
> {
> struct vfio_group *group =
> @@ -405,6 +432,11 @@ static int vfio_group_fops_open(struct inode *inode, struct file *filep)
> goto out_unlock;
> }
>
> + if (group->cdev_device_open_cnt) {
> + ret = -EBUSY;
> + goto out_unlock;
> + }
> +
> /*
> * Do we need multiple instances of the group open? Seems not.
> */
> @@ -479,6 +511,7 @@ static void vfio_group_release(struct device *dev)
> mutex_destroy(&group->device_lock);
> mutex_destroy(&group->group_lock);
> WARN_ON(group->iommu_group);
> + WARN_ON(group->cdev_device_open_cnt);
> ida_free(&vfio.group_ida, MINOR(group->dev.devt));
> kfree(group);
> }
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 854f2c97cb9a..b2f20b78a707 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -83,8 +83,11 @@ struct vfio_group {
> struct blocking_notifier_head notifier;
> struct iommufd_ctx *iommufd;
> spinlock_t kvm_ref_lock;
> + unsigned int cdev_device_open_cnt;
> };
>
> +int vfio_device_block_group(struct vfio_device *device);
> +void vfio_device_unblock_group(struct vfio_device *device);
> int vfio_device_set_group(struct vfio_device *device,
> enum vfio_group_type type);
> void vfio_device_remove_group(struct vfio_device *device);
