diff options
Diffstat (limited to 'drivers/vfio/device_cdev.c')
| -rw-r--r-- | drivers/vfio/device_cdev.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c new file mode 100644 index 0000000000..e75da0a70d --- /dev/null +++ b/drivers/vfio/device_cdev.c @@ -0,0 +1,228 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2023 Intel Corporation. + */ +#include <linux/vfio.h> +#include <linux/iommufd.h> + +#include "vfio.h" + +static dev_t device_devt; + +void vfio_init_device_cdev(struct vfio_device *device) +{ + device->device.devt = MKDEV(MAJOR(device_devt), device->index); + cdev_init(&device->cdev, &vfio_device_fops); + device->cdev.owner = THIS_MODULE; +} + +/* + * device access via the fd opened by this function is blocked until + * .open_device() is called successfully during BIND_IOMMUFD. + */ +int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep) +{ + struct vfio_device *device = container_of(inode->i_cdev, + struct vfio_device, cdev); + struct vfio_device_file *df; + int ret; + + /* Paired with the put in vfio_device_fops_release() */ + if (!vfio_device_try_get_registration(device)) + return -ENODEV; + + df = vfio_allocate_device_file(device); + if (IS_ERR(df)) { + ret = PTR_ERR(df); + goto err_put_registration; + } + + filep->private_data = df; + + return 0; + +err_put_registration: + vfio_device_put_registration(device); + return ret; +} + +static void vfio_df_get_kvm_safe(struct vfio_device_file *df) +{ + spin_lock(&df->kvm_ref_lock); + vfio_device_get_kvm_safe(df->device, df->kvm); + spin_unlock(&df->kvm_ref_lock); +} + +long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df, + struct vfio_device_bind_iommufd __user *arg) +{ + struct vfio_device *device = df->device; + struct vfio_device_bind_iommufd bind; + unsigned long minsz; + int ret; + + static_assert(__same_type(arg->out_devid, df->devid)); + + minsz = offsetofend(struct vfio_device_bind_iommufd, out_devid); + + if (copy_from_user(&bind, arg, minsz)) + return -EFAULT; + + if (bind.argsz < minsz || bind.flags || bind.iommufd < 0) + return -EINVAL; + + /* BIND_IOMMUFD only allowed for cdev fds */ + if (df->group) + return -EINVAL; + + ret = vfio_device_block_group(device); + if (ret) + return ret; + + mutex_lock(&device->dev_set->lock); + /* one device cannot be bound twice */ + if (df->access_granted) { + ret = -EINVAL; + goto out_unlock; + } + + df->iommufd = iommufd_ctx_from_fd(bind.iommufd); + if (IS_ERR(df->iommufd)) { + ret = PTR_ERR(df->iommufd); + df->iommufd = NULL; + goto out_unlock; + } + + /* + * Before the device open, get the KVM pointer currently + * associated with the device file (if there is) and obtain + * a reference. This reference is held until device closed. + * Save the pointer in the device for use by drivers. + */ + vfio_df_get_kvm_safe(df); + + ret = vfio_df_open(df); + if (ret) + goto out_put_kvm; + + ret = copy_to_user(&arg->out_devid, &df->devid, + sizeof(df->devid)) ? -EFAULT : 0; + if (ret) + goto out_close_device; + + device->cdev_opened = true; + /* + * Paired with smp_load_acquire() in vfio_device_fops::ioctl/ + * read/write/mmap + */ + smp_store_release(&df->access_granted, true); + mutex_unlock(&device->dev_set->lock); + return 0; + +out_close_device: + vfio_df_close(df); +out_put_kvm: + vfio_device_put_kvm(device); + iommufd_ctx_put(df->iommufd); + df->iommufd = NULL; +out_unlock: + mutex_unlock(&device->dev_set->lock); + vfio_device_unblock_group(device); + return ret; +} + +void vfio_df_unbind_iommufd(struct vfio_device_file *df) +{ + struct vfio_device *device = df->device; + + /* + * In the time of close, there is no contention with another one + * changing this flag. So read df->access_granted without lock + * and no smp_load_acquire() is ok. + */ + if (!df->access_granted) + return; + + mutex_lock(&device->dev_set->lock); + vfio_df_close(df); + vfio_device_put_kvm(device); + iommufd_ctx_put(df->iommufd); + device->cdev_opened = false; + mutex_unlock(&device->dev_set->lock); + vfio_device_unblock_group(device); +} + +int vfio_df_ioctl_attach_pt(struct vfio_device_file *df, + struct vfio_device_attach_iommufd_pt __user *arg) +{ + struct vfio_device *device = df->device; + struct vfio_device_attach_iommufd_pt attach; + unsigned long minsz; + int ret; + + minsz = offsetofend(struct vfio_device_attach_iommufd_pt, pt_id); + + if (copy_from_user(&attach, arg, minsz)) + return -EFAULT; + + if (attach.argsz < minsz || attach.flags) + return -EINVAL; + + mutex_lock(&device->dev_set->lock); + ret = device->ops->attach_ioas(device, &attach.pt_id); + if (ret) + goto out_unlock; + + if (copy_to_user(&arg->pt_id, &attach.pt_id, sizeof(attach.pt_id))) { + ret = -EFAULT; + goto out_detach; + } + mutex_unlock(&device->dev_set->lock); + + return 0; + +out_detach: + device->ops->detach_ioas(device); +out_unlock: + mutex_unlock(&device->dev_set->lock); + return ret; +} + +int vfio_df_ioctl_detach_pt(struct vfio_device_file *df, + struct vfio_device_detach_iommufd_pt __user *arg) +{ + struct vfio_device *device = df->device; + struct vfio_device_detach_iommufd_pt detach; + unsigned long minsz; + + minsz = offsetofend(struct vfio_device_detach_iommufd_pt, flags); + + if (copy_from_user(&detach, arg, minsz)) + return -EFAULT; + + if (detach.argsz < minsz || detach.flags) + return -EINVAL; + + mutex_lock(&device->dev_set->lock); + device->ops->detach_ioas(device); + mutex_unlock(&device->dev_set->lock); + + return 0; +} + +static char *vfio_device_devnode(const struct device *dev, umode_t *mode) +{ + return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev)); +} + +int vfio_cdev_init(struct class *device_class) +{ + device_class->devnode = vfio_device_devnode; + return alloc_chrdev_region(&device_devt, 0, + MINORMASK + 1, "vfio-dev"); +} + +void vfio_cdev_cleanup(void) +{ + unregister_chrdev_region(device_devt, MINORMASK + 1); +} |