This adds ioctl for userspace to bind device cdev fd to iommufd. VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA control provided by the iommufd. open_device op is called after bind_iommufd op. VFIO no iommu mode is indicated by passing VFIO_NOIOMMU_FD (-1) as iommufd value. Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx> Tested-by: Terrence Xu <terrence.xu@xxxxxxxxx> Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx> Tested-by: Yanting Jiang <yanting.jiang@xxxxxxxxx> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx> --- drivers/vfio/device_cdev.c | 152 +++++++++++++++++++++++++++++++++++++ drivers/vfio/vfio.h | 13 ++++ drivers/vfio/vfio_main.c | 5 ++ include/uapi/linux/vfio.h | 31 ++++++++ 4 files changed, 201 insertions(+) diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c index 1c640016a824..e3c51d2f5732 100644 --- a/drivers/vfio/device_cdev.c +++ b/drivers/vfio/device_cdev.c @@ -3,6 +3,7 @@ * Copyright (c) 2023 Intel Corporation. */ #include <linux/vfio.h> +#include <linux/iommufd.h> #include "vfio.h" @@ -44,6 +45,157 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep) return ret; } +static void vfio_device_get_kvm_safe(struct vfio_device_file *df) +{ + spin_lock(&df->kvm_ref_lock); + if (df->kvm) + _vfio_device_get_kvm_safe(df->device, df->kvm); + spin_unlock(&df->kvm_ref_lock); +} + +void vfio_device_cdev_close(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_device_close(df); + vfio_device_put_kvm(device); + if (df->iommufd) + iommufd_ctx_put(df->iommufd); + device->cdev_opened = false; + mutex_unlock(&device->dev_set->lock); + vfio_device_unblock_group(device); +} + +static int vfio_device_cdev_probe_noiommu(struct vfio_device *device) +{ + if (!capable(CAP_SYS_RAWIO)) + return -EPERM; + + if (!device->noiommu) + return -EINVAL; + + return 0; +} + +static struct iommufd_ctx *vfio_get_iommufd_from_fd(int fd) +{ + struct iommufd_ctx *iommufd; + struct fd f; + + f = fdget(fd); + if (!f.file) + return ERR_PTR(-EBADF); + + iommufd = iommufd_ctx_from_file(f.file); + + fdput(f); + return iommufd; +} + +long vfio_device_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; + bool is_noiommu; + 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) + return -EINVAL; + + /* BIND_IOMMUFD only allowed for cdev fds */ + if (df->group) + return -EINVAL; + + ret = vfio_device_block_group(device); + if (ret) + return ret; + + is_noiommu = bind.iommufd == VFIO_NOIOMMU_FD; + + mutex_lock(&device->dev_set->lock); + /* one device cannot be bound twice */ + if (df->access_granted) { + ret = -EINVAL; + goto out_unlock; + } + + if (is_noiommu) { + ret = vfio_device_cdev_probe_noiommu(device); + if (ret) + goto out_unlock; + } else { + df->iommufd = vfio_get_iommufd_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_device_get_kvm_safe(df); + + ret = vfio_device_open(df); + if (ret) + goto out_put_kvm; + + if (is_noiommu) { + dev_warn(device->dev, "device is bound to vfio-noiommu by user " + "(%s:%d)\n", current->comm, task_pid_nr(current)); + } else { + ret = copy_to_user(&arg->out_devid, &df->devid, + sizeof(df->devid)) ? -EFAULT : 0; + if (ret) + goto out_close_device; + } + + /* + * Paired with smp_load_acquire() in vfio_device_fops::ioctl/ + * read/write/mmap + */ + smp_store_release(&df->access_granted, true); + device->cdev_opened = true; + mutex_unlock(&device->dev_set->lock); + + return 0; + +out_close_device: + vfio_device_close(df); +out_put_kvm: + vfio_device_put_kvm(device); + if (!is_noiommu) { + iommufd_ctx_put(df->iommufd); + df->iommufd = NULL; + } +out_unlock: + mutex_unlock(&device->dev_set->lock); + vfio_device_unblock_group(device); + return ret; +} + static char *vfio_device_devnode(const struct device *dev, umode_t *mode) { return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev)); diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h index 3a8fd0e32f59..ace3d52b0928 100644 --- a/drivers/vfio/vfio.h +++ b/drivers/vfio/vfio.h @@ -281,6 +281,9 @@ static inline void vfio_device_del(struct vfio_device *device) void vfio_init_device_cdev(struct vfio_device *device); int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep); +void vfio_device_cdev_close(struct vfio_device_file *df); +long vfio_device_ioctl_bind_iommufd(struct vfio_device_file *df, + struct vfio_device_bind_iommufd __user *arg); int vfio_cdev_init(struct class *device_class); void vfio_cdev_cleanup(void); #else @@ -304,6 +307,16 @@ static inline int vfio_device_fops_cdev_open(struct inode *inode, return 0; } +static inline void vfio_device_cdev_close(struct vfio_device_file *df) +{ +} + +static inline long vfio_device_ioctl_bind_iommufd(struct vfio_device_file *df, + struct vfio_device_bind_iommufd __user *arg) +{ + return -EOPNOTSUPP; +} + static inline int vfio_cdev_init(struct class *device_class) { return 0; diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index 61f56d9b5e5f..0611e29e41a9 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -565,6 +565,8 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep) if (df->group) vfio_device_group_close(df); + else + vfio_device_cdev_close(df); vfio_device_put_registration(device); @@ -1138,6 +1140,9 @@ static long vfio_device_fops_unl_ioctl(struct file *filep, struct vfio_device *device = df->device; int ret; + if (cmd == VFIO_DEVICE_BIND_IOMMUFD) + return vfio_device_ioctl_bind_iommufd(df, (void __user *)arg); + /* Paired with smp_store_release() following vfio_device_open() */ if (!smp_load_acquire(&df->access_granted)) return -EINVAL; diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 5a34364e3b94..84d76630dd60 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -194,6 +194,37 @@ struct vfio_group_status { /* --------------- IOCTLs for DEVICE file descriptors --------------- */ +/* + * VFIO_DEVICE_BIND_IOMMUFD - _IOR(VFIO_TYPE, VFIO_BASE + 19, + * struct vfio_device_bind_iommufd) + * + * Bind a vfio_device to the specified iommufd. + * + * User is restricted from accessing the device before the binding operation + * is completed. + * + * Unbind is automatically conducted when device fd is closed. + * + * @argsz: user filled size of this data. + * @flags: reserved for future extension. + * @iommufd: iommufd to bind. VFIO_NOIOMMU_FD means noiommu. + * @out_devid: the device id generated by this bind. This field is valid + * as long as the input @iommufd is valid. Otherwise, it is + * meaningless. devid is a handle for this device and can be + * used in IOMMUFD commands. + * + * Return: 0 on success, -errno on failure. + */ +struct vfio_device_bind_iommufd { + __u32 argsz; + __u32 flags; + __s32 iommufd; +#define VFIO_NOIOMMU_FD (-1) + __u32 out_devid; +}; + +#define VFIO_DEVICE_BIND_IOMMUFD _IO(VFIO_TYPE, VFIO_BASE + 19) + /** * VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7, * struct vfio_device_info) -- 2.34.1