From 270bf4c019b94828229036a4ebc3361a30a7e9f3 Mon Sep 17 00:00:00 2001 From: Yi Liu Date: Tue, 18 Jul 2023 06:55:33 -0700 Subject: [PATCH] vfio: Add cdev_device_open_cnt to vfio_group 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 Reviewed-by: Jason Gunthorpe Reviewed-by: Eric Auger Tested-by: Terrence Xu Tested-by: Nicolin Chen Tested-by: Matthew Rosato Tested-by: Yanting Jiang Tested-by: Shameer Kolothum Tested-by: Zhenzhong Duan Signed-off-by: Yi Liu Link: https://lore.kernel.org/r/20230718135551.6592-9-yi.l.liu@intel.com Signed-off-by: Alex Williamson --- 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 088dd34..2751d61 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 4478a1e..ae7dd2c 100644 --- a/drivers/vfio/vfio.h +++ b/drivers/vfio/vfio.h @@ -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); -- 2.7.4