Commit 9c799c22 authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Alex Williamson
Browse files

vfio/mdev: add mdev available instance checking to the core 



Many of the mdev drivers use a simple counter for keeping track of the
available instances. Move this code to the core code and store the counter
in the mdev_parent. Implement it using correct locking, fixing mdpy.

Drivers just provide the value in the mdev_driver at registration time
and the core code takes care of maintaining it and exposing the value in
sysfs.

[hch: count instances per-parent instead of per-type, use an atomic_t
 to avoid taking mdev_list_lock in the show method]

Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarKirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: default avatarEric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220923092652.100656-15-hch@lst.de


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 685a1537

drivers/s390/cio/vfio_ccw_drv.c

+0 −1
Original line number Diff line number Diff line
@@ -141,7 +141,6 @@ static struct vfio_ccw_private *vfio_ccw_alloc_private(struct subchannel *sch) 
	INIT_LIST_HEAD(&private->crw);

	INIT_WORK(&private->io_work, vfio_ccw_sch_io_todo);

	INIT_WORK(&private->crw_work, vfio_ccw_crw_todo);

	atomic_set(&private->avail, 1);



	private->cp.guest_cp = kcalloc(CCWCHAIN_LEN_MAX, sizeof(struct ccw1),

				       GFP_KERNEL);

drivers/s390/cio/vfio_ccw_ops.c

+1 −14
Original line number Diff line number Diff line
@@ -44,13 +44,6 @@ static void vfio_ccw_dma_unmap(struct vfio_device *vdev, u64 iova, u64 length) 
	vfio_ccw_mdev_reset(private);

}



static unsigned int vfio_ccw_get_available(struct mdev_type *mtype)

{

	struct vfio_ccw_private *private = dev_get_drvdata(mtype->parent->dev);



	return atomic_read(&private->avail);

}



static int vfio_ccw_mdev_init_dev(struct vfio_device *vdev)

{

	struct vfio_ccw_private *private =
@@ -68,9 +61,6 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev) 
	if (private->state == VFIO_CCW_STATE_NOT_OPER)

		return -ENODEV;



	if (atomic_dec_if_positive(&private->avail) < 0)

		return -EPERM;



	ret = vfio_init_device(&private->vdev, &mdev->dev, &vfio_ccw_dev_ops);

	if (ret)

		return ret;
@@ -88,7 +78,6 @@ static int vfio_ccw_mdev_probe(struct mdev_device *mdev) 


err_put_vdev:

	vfio_put_device(&private->vdev);

	atomic_inc(&private->avail);

	return ret;

}
@@ -130,8 +119,6 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev) 
	 * cycle.

	 */

	wait_for_completion(&private->release_comp);



	atomic_inc(&private->avail);

}



static int vfio_ccw_mdev_open_device(struct vfio_device *vdev)
@@ -605,6 +592,7 @@ static const struct vfio_device_ops vfio_ccw_dev_ops = { 


struct mdev_driver vfio_ccw_mdev_driver = {

	.device_api = VFIO_DEVICE_API_CCW_STRING,

	.max_instances = 1,

	.driver = {

		.name = "vfio_ccw_mdev",

		.owner = THIS_MODULE,
@@ -612,5 +600,4 @@ struct mdev_driver vfio_ccw_mdev_driver = { 
	},

	.probe = vfio_ccw_mdev_probe,

	.remove = vfio_ccw_mdev_remove,

	.get_available = vfio_ccw_get_available,

};

drivers/s390/cio/vfio_ccw_private.h

+0 −2
Original line number Diff line number Diff line
@@ -73,7 +73,6 @@ struct vfio_ccw_crw { 
 * @sch: pointer to the subchannel

 * @state: internal state of the device

 * @completion: synchronization helper of the I/O completion

 * @avail: available for creating a mediated device

 * @io_region: MMIO region to input/output I/O arguments/results

 * @io_mutex: protect against concurrent update of I/O regions

 * @region: additional regions for other subchannel operations
@@ -97,7 +96,6 @@ struct vfio_ccw_private { 
	struct subchannel	*sch;

	int			state;

	struct completion	*completion;

	atomic_t		avail;

	struct ccw_io_region	*io_region;

	struct mutex		io_mutex;

	struct vfio_ccw_region *region;

drivers/s390/crypto/vfio_ap_ops.c

+1 −12
Original line number Diff line number Diff line
@@ -689,9 +689,6 @@ static int vfio_ap_mdev_init_dev(struct vfio_device *vdev) 
	struct ap_matrix_mdev *matrix_mdev =

		container_of(vdev, struct ap_matrix_mdev, vdev);



	if ((atomic_dec_if_positive(&matrix_dev->available_instances) < 0))

		return -EPERM;



	matrix_mdev->mdev = to_mdev_device(vdev->dev);

	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);

	matrix_mdev->pqap_hook = handle_pqap;
@@ -770,7 +767,6 @@ static void vfio_ap_mdev_unlink_fr_queues(struct ap_matrix_mdev *matrix_mdev) 


static void vfio_ap_mdev_release_dev(struct vfio_device *vdev)

{

	atomic_inc(&matrix_dev->available_instances);

	vfio_free_device(vdev);

}
@@ -790,11 +786,6 @@ static void vfio_ap_mdev_remove(struct mdev_device *mdev) 
	vfio_put_device(&matrix_mdev->vdev);

}



static unsigned int vfio_ap_mdev_get_available(struct mdev_type *mtype)

{

	return atomic_read(&matrix_dev->available_instances);

}



#define MDEV_SHARING_ERR "Userspace may not re-assign queue %02lx.%04lx " \

			 "already assigned to %s"
@@ -1772,6 +1763,7 @@ static const struct vfio_device_ops vfio_ap_matrix_dev_ops = { 


static struct mdev_driver vfio_ap_matrix_driver = {

	.device_api = VFIO_DEVICE_API_AP_STRING,

	.max_instances = MAX_ZDEV_ENTRIES_EXT,

	.driver = {

		.name = "vfio_ap_mdev",

		.owner = THIS_MODULE,
@@ -1780,15 +1772,12 @@ static struct mdev_driver vfio_ap_matrix_driver = { 
	},

	.probe = vfio_ap_mdev_probe,

	.remove = vfio_ap_mdev_remove,

	.get_available = vfio_ap_mdev_get_available,

};



int vfio_ap_mdev_register(void)

{

	int ret;



	atomic_set(&matrix_dev->available_instances, MAX_ZDEV_ENTRIES_EXT);



	ret = mdev_register_driver(&vfio_ap_matrix_driver);

	if (ret)

		return ret;

drivers/s390/crypto/vfio_ap_private.h

+0 −2
Original line number Diff line number Diff line
@@ -29,7 +29,6 @@ 
 * struct ap_matrix_dev - Contains the data for the matrix device.

 *

 * @device:	generic device structure associated with the AP matrix device

 * @available_instances: number of mediated matrix devices that can be created

 * @info:	the struct containing the output from the PQAP(QCI) instruction

 * @mdev_list:	the list of mediated matrix devices created

 * @mdevs_lock: mutex for locking the AP matrix device. This lock will be
@@ -46,7 +45,6 @@ 
 */

struct ap_matrix_dev {

	struct device device;

	atomic_t available_instances;

	struct ap_config_info info;

	struct list_head mdev_list;

	struct mutex mdevs_lock; /* serializes access to each ap_matrix_mdev */