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vfio: Add cdev_device_open_cnt to vfio_group

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This is 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@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Yanting Jiang <yanting.jiang@intel.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Tested-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20230718135551.6592-9-yi.l.liu@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Yi Liu 2023-07-18 06:55:33 -07:00 committed by Alex Williamson
parent 82d93f580f
commit 270bf4c019
2 changed files with 36 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

33
drivers/vfio/group.c
View file

@ -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);
}

3
drivers/vfio/vfio.h
View file

@ -84,8 +84,11 @@ 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);