Re: [PATCH 2/3] vfio: Add VFIO_DEVICE_PASID_[AT|DE]TACH_IOMMUFD_PT

[Alex Williamson <alex.williamson@redhat.com>]

On Sun, 26 Nov 2023 22:39:08 -0800
Yi Liu <yi.l.liu@intel.com> wrote:

> This adds ioctls for the userspace to attach a given pasid of a vfio
> device to/from an IOAS/HWPT.
> 
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/vfio/device_cdev.c | 45 +++++++++++++++++++++++++++++++
>  drivers/vfio/vfio.h        |  4 +++
>  drivers/vfio/vfio_main.c   |  8 ++++++
>  include/uapi/linux/vfio.h  | 55 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 112 insertions(+)
> 
> diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> index e75da0a70d1f..c2ac7ed44537 100644
> --- a/drivers/vfio/device_cdev.c
> +++ b/drivers/vfio/device_cdev.c
> @@ -210,6 +210,51 @@ int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
>  	return 0;
>  }
>  
> +int vfio_df_ioctl_pasid_attach_pt(struct vfio_device_file *df,
> +				  struct vfio_device_pasid_attach_iommufd_pt __user *arg)
> +{
> +	struct vfio_device *device = df->device;
> +	struct vfio_device_pasid_attach_iommufd_pt attach;
> +	unsigned long minsz;
> +	int ret;
> +
> +	minsz = offsetofend(struct vfio_device_pasid_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->pasid_attach_ioas(device, attach.pasid, &attach.pt_id);

These callbacks were only implemented for vfio-pci in the previous
patch but they're called unconditionally.  Thanks,

Alex

> +	mutex_unlock(&device->dev_set->lock);
> +
> +	return ret;
> +}
> +
> +int vfio_df_ioctl_pasid_detach_pt(struct vfio_device_file *df,
> +				  struct vfio_device_pasid_detach_iommufd_pt __user *arg)
> +{
> +	struct vfio_device *device = df->device;
> +	struct vfio_device_pasid_detach_iommufd_pt detach;
> +	unsigned long minsz;
> +
> +	minsz = offsetofend(struct vfio_device_pasid_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->pasid_detach_ioas(device, detach.pasid);
> +	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));
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 307e3f29b527..d228cdb6b345 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -353,6 +353,10 @@ int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
>  			    struct vfio_device_attach_iommufd_pt __user *arg);
>  int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
>  			    struct vfio_device_detach_iommufd_pt __user *arg);
> +int vfio_df_ioctl_pasid_attach_pt(struct vfio_device_file *df,
> +				  struct vfio_device_pasid_attach_iommufd_pt __user *arg);
> +int vfio_df_ioctl_pasid_detach_pt(struct vfio_device_file *df,
> +				  struct vfio_device_pasid_detach_iommufd_pt __user *arg);
>  
>  #if IS_ENABLED(CONFIG_VFIO_DEVICE_CDEV)
>  void vfio_init_device_cdev(struct vfio_device *device);
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 8d4995ada74a..ff50c239873d 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -1240,6 +1240,14 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
>  		case VFIO_DEVICE_DETACH_IOMMUFD_PT:
>  			ret = vfio_df_ioctl_detach_pt(df, uptr);
>  			goto out;
> +
> +		case VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT:
> +			ret = vfio_df_ioctl_pasid_attach_pt(df, uptr);
> +			goto out;
> +
> +		case VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT:
> +			ret = vfio_df_ioctl_pasid_detach_pt(df, uptr);
> +			goto out;
>  		}
>  	}
>  
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 94b3badefde3..495193629029 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -977,6 +977,61 @@ struct vfio_device_detach_iommufd_pt {
>  
>  #define VFIO_DEVICE_DETACH_IOMMUFD_PT		_IO(VFIO_TYPE, VFIO_BASE + 20)
>  
> +/*
> + * VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 21,
> + *					      struct vfio_device_pasid_attach_iommufd_pt)
> + * @argsz:	User filled size of this data.
> + * @flags:	Must be 0.
> + * @pasid:	The pasid to be attached.
> + * @pt_id:	Input the target id which can represent an ioas or a hwpt
> + *		allocated via iommufd subsystem.
> + *		Output the input ioas id or the attached hwpt id which could
> + *		be the specified hwpt itself or a hwpt automatically created
> + *		for the specified ioas by kernel during the attachment.
> + *
> + * Associate a pasid (of a cdev device) with an address space within the
> + * bound iommufd. Undo by VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT or device fd
> + * close. This is only allowed on cdev fds.
> + *
> + * If a pasid is currently attached to a valid hw_pagetable (hwpt), without
> + * doing a VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT, a second
> + * VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT ioctl passing in another hwpt id is
> + * allowed. This action, also known as a hwpt replacement, will replace the
> + * pasid's currently attached hwpt with a new hwpt corresponding to the given
> + * @pt_id.
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +struct vfio_device_pasid_attach_iommufd_pt {
> +	__u32	argsz;
> +	__u32	flags;
> +	__u32	pasid;
> +	__u32	pt_id;
> +};
> +
> +#define VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT	_IO(VFIO_TYPE, VFIO_BASE + 21)
> +
> +/*
> + * VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 22,
> + *					      struct vfio_device_pasid_detach_iommufd_pt)
> + * @argsz:	User filled size of this data.
> + * @flags:	Must be 0.
> + * @pasid:	The pasid to be detached.
> + *
> + * Remove the association of a pasid (of a cdev device) and its current
> + * associated address space.  After it, the pasid of the device should be in
> + * a blocking DMA state.  This is only allowed on cdev fds.
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +struct vfio_device_pasid_detach_iommufd_pt {
> +	__u32	argsz;
> +	__u32	flags;
> +	__u32	pasid;
> +};
> +
> +#define VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT	_IO(VFIO_TYPE, VFIO_BASE + 22)
> +
>  /*
>   * Provide support for setting a PCI VF Token, which is used as a shared
>   * secret between PF and VF drivers.  This feature may only be set on a