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

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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: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/r/20220923092652.100656-15-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Jason Gunthorpe
2022-09-23 11:26:52 +02:00
committed by Alex Williamson
parent 685a1537f4
commit 9c799c224d
9 changed files with 32 additions and 53 deletions
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22
samples/vfio-mdev/mdpy.c
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@@ -42,11 +42,6 @@
MODULE_LICENSE("GPL v2");
static int max_devices = 4;
module_param_named(count, max_devices, int, 0444);
MODULE_PARM_DESC(count, "number of " MDPY_NAME " devices");
#define MDPY_TYPE_1 "vga"
#define MDPY_TYPE_2 "xga"
#define MDPY_TYPE_3 "hd"
@@ -93,7 +88,6 @@ static struct class *mdpy_class;
static struct cdev mdpy_cdev;
static struct device mdpy_dev;
static struct mdev_parent mdpy_parent;
static u32 mdpy_count;
static const struct vfio_device_ops mdpy_dev_ops;
/* State of each mdev device */
@@ -235,9 +229,6 @@ static int mdpy_init_dev(struct vfio_device *vdev)
u32 fbsize;
int ret = -ENOMEM;
if (mdpy_count >= max_devices)
return ret;
mdev_state->vconfig = kzalloc(MDPY_CONFIG_SPACE_SIZE, GFP_KERNEL);
if (!mdev_state->vconfig)
return ret;
@@ -257,8 +248,6 @@ static int mdpy_init_dev(struct vfio_device *vdev)
dev_info(vdev->dev, "%s: %s (%dx%d)\n", __func__, type->type.pretty_name,
type->width, type->height);
mdpy_count++;
return 0;
out_vconfig:
@@ -292,7 +281,6 @@ static void mdpy_release_dev(struct vfio_device *vdev)
struct mdev_state *mdev_state =
container_of(vdev, struct mdev_state, vdev);
mdpy_count--;
vfree(mdev_state->memblk);
kfree(mdev_state->vconfig);
vfio_free_device(vdev);
@@ -669,11 +657,6 @@ static ssize_t mdpy_show_description(struct mdev_type *mtype, char *buf)
type->width, type->height);
}
static unsigned int mdpy_get_available(struct mdev_type *mtype)
{
return max_devices - mdpy_count;
}
static const struct vfio_device_ops mdpy_dev_ops = {
.init = mdpy_init_dev,
.release = mdpy_release_dev,
@@ -685,6 +668,7 @@ static const struct vfio_device_ops mdpy_dev_ops = {
static struct mdev_driver mdpy_driver = {
.device_api = VFIO_DEVICE_API_PCI_STRING,
.max_instances = 4,
.driver = {
.name = "mdpy",
.owner = THIS_MODULE,
@@ -693,7 +677,6 @@ static struct mdev_driver mdpy_driver = {
},
.probe = mdpy_probe,
.remove = mdpy_remove,
.get_available = mdpy_get_available,
.show_description = mdpy_show_description,
};
@@ -770,5 +753,8 @@ static void __exit mdpy_dev_exit(void)
mdpy_class = NULL;
}
module_param_named(count, mdpy_driver.max_instances, int, 0444);
MODULE_PARM_DESC(count, "number of " MDPY_NAME " devices");
module_init(mdpy_dev_init)
module_exit(mdpy_dev_exit)