8b6f173a4c
This adds cdev support for vfio_device. It allows the user to directly
open a vfio device w/o using the legacy container/group interface, as a
prerequisite for supporting new iommu features like nested translation
and etc.
The device fd opened in this manner doesn't have the capability to access
the device as the fops open() doesn't open the device until the successful
VFIO_DEVICE_BIND_IOMMUFD ioctl which will be added in a later patch.
With this patch, devices registered to vfio core would have both the legacy
group and the new device interfaces created.
- group interface : /dev/vfio/$groupID
- device interface: /dev/vfio/devices/vfioX - normal device
("X" is a unique number across vfio devices)
For a given device, the user can identify the matching vfioX by searching
the vfio-dev folder under the sysfs path of the device. Take PCI device
(0000:6a:01.0) as an example, /sys/bus/pci/devices/0000\:6a\:01.0/vfio-dev/vfioX
implies the matching vfioX under /dev/vfio/devices/, and vfio-dev/vfioX/dev
contains the major:minor number of the matching /dev/vfio/devices/vfioX.
The user can get device fd by opening the /dev/vfio/devices/vfioX.
The vfio_device cdev logic in this patch:
*) __vfio_register_dev() path ends up doing cdev_device_add() for each
vfio_device if VFIO_DEVICE_CDEV configured.
*) vfio_unregister_group_dev() path does cdev_device_del();
cdev interface does not support noiommu devices, so VFIO only creates the
legacy group interface for the physical devices that do not have IOMMU.
noiommu users should use the legacy group interface.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.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/20230718135551.6592-19-yi.l.liu@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
64 lines
1.4 KiB
C
64 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2023 Intel Corporation.
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*/
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#include <linux/vfio.h>
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#include "vfio.h"
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static dev_t device_devt;
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void vfio_init_device_cdev(struct vfio_device *device)
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{
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device->device.devt = MKDEV(MAJOR(device_devt), device->index);
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cdev_init(&device->cdev, &vfio_device_fops);
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device->cdev.owner = THIS_MODULE;
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}
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/*
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* device access via the fd opened by this function is blocked until
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* .open_device() is called successfully during BIND_IOMMUFD.
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*/
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int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep)
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{
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struct vfio_device *device = container_of(inode->i_cdev,
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struct vfio_device, cdev);
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struct vfio_device_file *df;
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int ret;
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/* Paired with the put in vfio_device_fops_release() */
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if (!vfio_device_try_get_registration(device))
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return -ENODEV;
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df = vfio_allocate_device_file(device);
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if (IS_ERR(df)) {
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ret = PTR_ERR(df);
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goto err_put_registration;
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}
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filep->private_data = df;
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return 0;
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err_put_registration:
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vfio_device_put_registration(device);
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return ret;
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}
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static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
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{
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return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
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}
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int vfio_cdev_init(struct class *device_class)
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{
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device_class->devnode = vfio_device_devnode;
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return alloc_chrdev_region(&device_devt, 0,
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MINORMASK + 1, "vfio-dev");
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}
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void vfio_cdev_cleanup(void)
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{
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unregister_chrdev_region(device_devt, MINORMASK + 1);
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}
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