On Fri, 2 Jun 2023 05:16:47 -0700 Yi Liu <[email protected]> wrote:
> 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. > > Tested-by: Yanting Jiang <[email protected]> > Tested-by: Shameer Kolothum <[email protected]> > Tested-by: Terrence Xu <[email protected]> > Signed-off-by: Yi Liu <[email protected]> > --- > drivers/vfio/device_cdev.c | 123 +++++++++++++++++++++++++++++++++++++ > drivers/vfio/vfio.h | 13 ++++ > drivers/vfio/vfio_main.c | 5 ++ > include/linux/vfio.h | 3 +- > include/uapi/linux/vfio.h | 27 ++++++++ > 5 files changed, 170 insertions(+), 1 deletion(-) > > diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c > index 1c640016a824..a4498ddbe774 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 +45,128 @@ 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_df_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_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); > +} > + > +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_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 = 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_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; > + > + /* > + * 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_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; > +} > + > 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 d12b5b524bfc..42de40d2cd4d 100644 > --- a/drivers/vfio/vfio.h > +++ b/drivers/vfio/vfio.h > @@ -287,6 +287,9 @@ static inline void vfio_device_del(struct vfio_device > *device) > } > > int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep); > +void vfio_df_cdev_close(struct vfio_device_file *df); > +long vfio_df_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 > @@ -310,6 +313,16 @@ static inline int vfio_device_fops_cdev_open(struct > inode *inode, > return 0; > } > > +static inline void vfio_df_cdev_close(struct vfio_device_file *df) > +{ > +} > + > +static inline long vfio_df_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 ef55af75f459..9ba4d420eda2 100644 > --- a/drivers/vfio/vfio_main.c > +++ b/drivers/vfio/vfio_main.c > @@ -572,6 +572,8 @@ static int vfio_device_fops_release(struct inode *inode, > struct file *filep) > > if (df->group) > vfio_df_group_close(df); > + else > + vfio_df_cdev_close(df); > > vfio_device_put_registration(device); > > @@ -1145,6 +1147,9 @@ 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_df_ioctl_bind_iommufd(df, (void __user *)arg); > + > /* Paired with smp_store_release() following vfio_df_open() */ > if (!smp_load_acquire(&df->access_granted)) > return -EINVAL; > diff --git a/include/linux/vfio.h b/include/linux/vfio.h > index 83cc5dc28b7a..e80a8ac86e46 100644 > --- a/include/linux/vfio.h > +++ b/include/linux/vfio.h > @@ -66,6 +66,7 @@ struct vfio_device { > struct iommufd_device *iommufd_device; > bool iommufd_attached; > #endif > + bool cdev_opened:1; Perhaps a more strongly defined data type here as well and roll iommufd_attached into the same bit field scheme. > }; > > /** > @@ -170,7 +171,7 @@ vfio_iommufd_device_hot_reset_devid(struct vfio_device > *vdev, > > static inline bool vfio_device_cdev_opened(struct vfio_device *device) > { > - return false; > + return device->cdev_opened; > } > > /** > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h > index f753124e1c82..7296012b7f36 100644 > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -194,6 +194,33 @@ struct vfio_group_status { > > /* --------------- IOCTLs for DEVICE file descriptors --------------- */ > > +/* > + * VFIO_DEVICE_BIND_IOMMUFD - _IOR(VFIO_TYPE, VFIO_BASE + 18, > + * struct vfio_device_bind_iommufd) > + * @argsz: User filled size of this data. > + * @flags: Must be 0. > + * @iommufd: iommufd to bind. > + * @out_devid: The device id generated by this bind. devid is a > handle for > + * this device/iommufd bond and can be used in IOMMUFD commands. > + * > + * 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. > + * > + * Return: 0 on success, -errno on failure. > + */ > +struct vfio_device_bind_iommufd { > + __u32 argsz; > + __u32 flags; > + __s32 iommufd; > + __u32 out_devid; > +}; > + > +#define VFIO_DEVICE_BIND_IOMMUFD _IO(VFIO_TYPE, VFIO_BASE + 18) > + Why are we still defining device ioctls 18-20 before existing device ioctls? 18 should be defined after 17... Thanks, Alex > /** > * VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7, > * struct vfio_device_info)
