> From: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Sent: Thursday, March 30, 2023 5:19 AM
>
>
> Nit, ATDETACH? [AT|DE]TACH?
[AT|DE]TACH 😊
> On Mon, 27 Mar 2023 02:40:45 -0700
> Yi Liu <yi.l.liu@xxxxxxxxx> wrote:
>
> > This adds ioctl for userspace to attach device cdev fd to and detach
> > from IOAS/hw_pagetable managed by iommufd.
> >
> > VFIO_DEVICE_ATTACH_IOMMUFD_PT: attach vfio device to IOAS, hw_pagetable
> > managed by iommufd. Attach can be
> > undo by VFIO_DEVICE_DETACH_IOMMUFD_PT
> > or device fd close.
> > VFIO_DEVICE_DETACH_IOMMUFD_PT: detach vfio device from the current
> attached
> > IOAS or hw_pagetable managed by iommufd.
> >
> > Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Tested-by: Terrence Xu <terrence.xu@xxxxxxxxx>
> > Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> > Tested-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
> > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> > ---
> > drivers/vfio/device_cdev.c | 85 ++++++++++++++++++++++++++++++++++++++
> > drivers/vfio/vfio.h | 16 +++++++
> > drivers/vfio/vfio_main.c | 8 ++++
> > include/uapi/linux/vfio.h | 52 +++++++++++++++++++++++
> > 4 files changed, 161 insertions(+)
> >
> > diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> > index 2b563bac50b9..b5de997bff6d 100644
> > --- a/drivers/vfio/device_cdev.c
> > +++ b/drivers/vfio/device_cdev.c
> > @@ -197,6 +197,91 @@ long vfio_device_ioctl_bind_iommufd(struct
> vfio_device_file *df,
> > return ret;
> > }
> >
> > +int vfio_ioctl_device_attach(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;
> > +
> > + static_assert(__same_type(arg->pt_id, attach.pt_id));
>
> Same comment as previous, given these are the same field of the same
> structure, I don't understand how this could ever assert.
yes, will remove it.
>
> > +
> > + 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;
> > +
> > + if (!device->ops->bind_iommufd)
> > + return -ENODEV;
>
> Same as previous, we already require this to enable cdev support, so
> this seems ultra paranoid.
will remove it.
>
> > +
> > + /* ATTACH only allowed for cdev fds */
> > + if (df->group)
> > + return -EINVAL;
> > +
> > + mutex_lock(&device->dev_set->lock);
> > + /* noiommufd mode doesn't allow attach */
> > + if (!df->iommufd) {
> > + ret = -EOPNOTSUPP;
> > + goto out_unlock;
> > + }
> > +
> > + ret = device->ops->attach_ioas(device, &attach.pt_id);
> > + if (ret)
> > + goto out_unlock;
> > +
> > + ret = copy_to_user(&arg->pt_id, &attach.pt_id,
> > + sizeof(attach.pt_id)) ? -EFAULT : 0;
> > + if (ret)
> > + 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_ioctl_device_detach(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;
> > +
> > + if (!device->ops->bind_iommufd)
> > + return -ENODEV;
> > +
> > + /* DETACH only allowed for cdev fds */
> > + if (df->group)
> > + return -EINVAL;
> > +
> > + mutex_lock(&device->dev_set->lock);
> > + /* noiommufd mode doesn't support detach */
> > + if (!df->iommufd) {
> > + mutex_unlock(&device->dev_set->lock);
> > + return -EOPNOTSUPP;
> > + }
> > + device->ops->detach_ioas(device);
> > + mutex_unlock(&device->dev_set->lock);
> > +
> > + return 0;
> > +}
>
> For both of these, can't a user trigger the
> WARN_ON(!vdev->iommufd_device) if they call either of these before
> VFIO_DEVICE_BIND_IOMMUFD? Thanks,
if VFIO_DEVICE_BIND_IOMMUFD is not done, the ATTACH/DETACH
shall be blocked, so it won't trigger the WARN_ON which is in the
attach_ioas and detach_ioas callback.
Regards,
Yi Liu
>
> > +
> > 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 ace3d52b0928..c199e410db18 100644
> > --- a/drivers/vfio/vfio.h
> > +++ b/drivers/vfio/vfio.h
> > @@ -284,6 +284,10 @@ 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_ioctl_device_attach(struct vfio_device_file *df,
> > + struct vfio_device_attach_iommufd_pt __user *arg);
> > +int vfio_ioctl_device_detach(struct vfio_device_file *df,
> > + struct vfio_device_detach_iommufd_pt __user *arg);
> > int vfio_cdev_init(struct class *device_class);
> > void vfio_cdev_cleanup(void);
> > #else
> > @@ -317,6 +321,18 @@ static inline long vfio_device_ioctl_bind_iommufd(struct
> vfio_device_file *df,
> > return -EOPNOTSUPP;
> > }
> >
> > +static inline int vfio_ioctl_device_attach(struct vfio_device_file *df,
> > + struct vfio_device_attach_iommufd_pt
> __user *arg)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > +
> > +static inline int vfio_ioctl_device_detach(struct vfio_device_file *df,
> > + struct vfio_device_detach_iommufd_pt
> __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 375086c8803f..896d8bb49585 100644
> > --- a/drivers/vfio/vfio_main.c
> > +++ b/drivers/vfio/vfio_main.c
> > @@ -1150,6 +1150,14 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
> > ret = vfio_ioctl_device_feature(device, (void __user *)arg);
> > break;
> >
> > + case VFIO_DEVICE_ATTACH_IOMMUFD_PT:
> > + ret = vfio_ioctl_device_attach(df, (void __user *)arg);
> > + break;
> > +
> > + case VFIO_DEVICE_DETACH_IOMMUFD_PT:
> > + ret = vfio_ioctl_device_detach(df, (void __user *)arg);
> > + break;
> > +
> > default:
> > if (unlikely(!device->ops->ioctl))
> > ret = -EINVAL;
> > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> > index 62b2f2497525..bf6c97e759c7 100644
> > --- a/include/uapi/linux/vfio.h
> > +++ b/include/uapi/linux/vfio.h
> > @@ -231,6 +231,58 @@ struct vfio_device_bind_iommufd {
> >
> > #define VFIO_DEVICE_BIND_IOMMUFD _IO(VFIO_TYPE, VFIO_BASE + 19)
> >
> > +/*
> > + * VFIO_DEVICE_ATTACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 20,
> > + * struct vfio_device_attach_iommufd_pt)
> > + *
> > + * Attach a vfio device to an iommufd address space specified by IOAS
> > + * id or hw_pagetable (hwpt) id.
> > + *
> > + * Available only after a device has been bound to iommufd via
> > + * VFIO_DEVICE_BIND_IOMMUFD
> > + *
> > + * Undo by VFIO_DEVICE_DETACH_IOMMUFD_PT or device fd close.
> > + *
> > + * @argsz: user filled size of this data.
> > + * @flags: must be 0.
> > + * @pt_id: Input the target id which can represent an ioas or a hwpt
> > + * allocated via iommufd subsystem.
> > + * Output 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.
> > + *
> > + * Return: 0 on success, -errno on failure.
> > + */
> > +struct vfio_device_attach_iommufd_pt {
> > + __u32 argsz;
> > + __u32 flags;
> > + __u32 pt_id;
> > +};
> > +
> > +#define VFIO_DEVICE_ATTACH_IOMMUFD_PT _IO(VFIO_TYPE,
> VFIO_BASE + 20)
> > +
> > +/*
> > + * VFIO_DEVICE_DETACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 21,
> > + * struct vfio_device_detach_iommufd_pt)
> > + *
> > + * Detach a vfio device from the iommufd address space it has been
> > + * attached to. After it, device should be in a blocking DMA state.
> > + *
> > + * Available only after a device has been bound to iommufd via
> > + * VFIO_DEVICE_BIND_IOMMUFD.
> > + *
> > + * @argsz: user filled size of this data.
> > + * @flags: must be 0.
> > + *
> > + * Return: 0 on success, -errno on failure.
> > + */
> > +struct vfio_device_detach_iommufd_pt {
> > + __u32 argsz;
> > + __u32 flags;
> > +};
> > +
> > +#define VFIO_DEVICE_DETACH_IOMMUFD_PT _IO(VFIO_TYPE,
> VFIO_BASE + 21)
> > +
> > /**
> > * VFIO_DEVICE_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 7,
> > * struct vfio_device_info)
