Re: [Intel-gfx] [PATCH v11 13/23] vfio-iommufd: Add detach_ioas support for physical VFIO devices

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

On Sat, 13 May 2023 06:28:17 -0700
Yi Liu <yi.l.liu@intel.com> wrote:

> this prepares for adding DETACH ioctl for physical VFIO devices.
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Tested-by: Terrence Xu <terrence.xu@intel.com>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  Documentation/driver-api/vfio.rst             |  8 +++++---
>  drivers/vfio/fsl-mc/vfio_fsl_mc.c             |  1 +
>  drivers/vfio/iommufd.c                        | 20 +++++++++++++++++++
>  .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c    |  2 ++
>  drivers/vfio/pci/mlx5/main.c                  |  1 +
>  drivers/vfio/pci/vfio_pci.c                   |  1 +
>  drivers/vfio/platform/vfio_amba.c             |  1 +
>  drivers/vfio/platform/vfio_platform.c         |  1 +
>  drivers/vfio/vfio_main.c                      |  3 ++-
>  include/linux/vfio.h                          |  8 +++++++-
>  10 files changed, 41 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/driver-api/vfio.rst b/Documentation/driver-api/vfio.rst
> index 68abc089d6dd..363e12c90b87 100644
> --- a/Documentation/driver-api/vfio.rst
> +++ b/Documentation/driver-api/vfio.rst
> @@ -279,6 +279,7 @@ similar to a file operations structure::
>  					struct iommufd_ctx *ictx, u32 *out_device_id);
>  		void	(*unbind_iommufd)(struct vfio_device *vdev);
>  		int	(*attach_ioas)(struct vfio_device *vdev, u32 *pt_id);
> +		void	(*detach_ioas)(struct vfio_device *vdev);
>  		int	(*open_device)(struct vfio_device *vdev);
>  		void	(*close_device)(struct vfio_device *vdev);
>  		ssize_t	(*read)(struct vfio_device *vdev, char __user *buf,
> @@ -315,9 +316,10 @@ container_of().
>  	- The [un]bind_iommufd callbacks are issued when the device is bound to
>  	  and unbound from iommufd.
>  
> -	- The attach_ioas callback is issued when the device is attached to an
> -	  IOAS managed by the bound iommufd. The attached IOAS is automatically
> -	  detached when the device is unbound from iommufd.
> +	- The [de]attach_ioas callback is issued when the device is attached to
> +	  and detached from an IOAS managed by the bound iommufd. However, the
> +	  attached IOAS can also be automatically detached when the device is
> +	  unbound from iommufd.
>  
>  	- The read/write/mmap callbacks implement the device region access defined
>  	  by the device's own VFIO_DEVICE_GET_REGION_INFO ioctl.
> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> index c89a047a4cd8..d540cf683d93 100644
> --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
> @@ -594,6 +594,7 @@ static const struct vfio_device_ops vfio_fsl_mc_ops = {
>  	.bind_iommufd	= vfio_iommufd_physical_bind,
>  	.unbind_iommufd	= vfio_iommufd_physical_unbind,
>  	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
> +	.detach_ioas	= vfio_iommufd_physical_detach_ioas,
>  };
>  
>  static struct fsl_mc_driver vfio_fsl_mc_driver = {
> diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
> index 07b58c4625b5..e3953e1617a5 100644
> --- a/drivers/vfio/iommufd.c
> +++ b/drivers/vfio/iommufd.c
> @@ -167,6 +167,14 @@ int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
>  {
>  	int rc;
>  
> +	lockdep_assert_held(&vdev->dev_set->lock);
> +
> +	if (WARN_ON(!vdev->iommufd_device))
> +		return -EINVAL;
> +
> +	if (vdev->iommufd_attached)
> +		return -EBUSY;
> +
>  	rc = iommufd_device_attach(vdev->iommufd_device, pt_id);
>  	if (rc)
>  		return rc;
> @@ -175,6 +183,18 @@ int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
>  }
>  EXPORT_SYMBOL_GPL(vfio_iommufd_physical_attach_ioas);
>  
> +void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev)
> +{
> +	lockdep_assert_held(&vdev->dev_set->lock);
> +
> +	if (WARN_ON(!vdev->iommufd_device) || !vdev->iommufd_attached)
> +		return;
> +
> +	iommufd_device_detach(vdev->iommufd_device);
> +	vdev->iommufd_attached = false;
> +}
> +EXPORT_SYMBOL_GPL(vfio_iommufd_physical_detach_ioas);

Can't a user trigger this WARN_ON by simply repeatedly calling the
to-be-added detach ioctl?  Thanks,

Alex

> +
>  /*
>   * The emulated standard ops mean that vfio_device is going to use the
>   * "mdev path" and will call vfio_pin_pages()/vfio_dma_rw(). Drivers using this
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> index a117eaf21c14..b2f9778c8366 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> @@ -1373,6 +1373,7 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_migrn_ops = {
>  	.bind_iommufd = vfio_iommufd_physical_bind,
>  	.unbind_iommufd = vfio_iommufd_physical_unbind,
>  	.attach_ioas = vfio_iommufd_physical_attach_ioas,
> +	.detach_ioas = vfio_iommufd_physical_detach_ioas,
>  };
>  
>  static const struct vfio_device_ops hisi_acc_vfio_pci_ops = {
> @@ -1391,6 +1392,7 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_ops = {
>  	.bind_iommufd = vfio_iommufd_physical_bind,
>  	.unbind_iommufd = vfio_iommufd_physical_unbind,
>  	.attach_ioas = vfio_iommufd_physical_attach_ioas,
> +	.detach_ioas = vfio_iommufd_physical_detach_ioas,
>  };
>  
>  static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
> index d95fd382814c..42ec574a8622 100644
> --- a/drivers/vfio/pci/mlx5/main.c
> +++ b/drivers/vfio/pci/mlx5/main.c
> @@ -1320,6 +1320,7 @@ static const struct vfio_device_ops mlx5vf_pci_ops = {
>  	.bind_iommufd = vfio_iommufd_physical_bind,
>  	.unbind_iommufd = vfio_iommufd_physical_unbind,
>  	.attach_ioas = vfio_iommufd_physical_attach_ioas,
> +	.detach_ioas = vfio_iommufd_physical_detach_ioas,
>  };
>  
>  static int mlx5vf_pci_probe(struct pci_dev *pdev,
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 29091ee2e984..cb5b7f865d58 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -141,6 +141,7 @@ static const struct vfio_device_ops vfio_pci_ops = {
>  	.bind_iommufd	= vfio_iommufd_physical_bind,
>  	.unbind_iommufd	= vfio_iommufd_physical_unbind,
>  	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
> +	.detach_ioas	= vfio_iommufd_physical_detach_ioas,
>  };
>  
>  static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> diff --git a/drivers/vfio/platform/vfio_amba.c b/drivers/vfio/platform/vfio_amba.c
> index 83fe54015595..6464b3939ebc 100644
> --- a/drivers/vfio/platform/vfio_amba.c
> +++ b/drivers/vfio/platform/vfio_amba.c
> @@ -119,6 +119,7 @@ static const struct vfio_device_ops vfio_amba_ops = {
>  	.bind_iommufd	= vfio_iommufd_physical_bind,
>  	.unbind_iommufd	= vfio_iommufd_physical_unbind,
>  	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
> +	.detach_ioas	= vfio_iommufd_physical_detach_ioas,
>  };
>  
>  static const struct amba_id pl330_ids[] = {
> diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c
> index 22a1efca32a8..8cf22fa65baa 100644
> --- a/drivers/vfio/platform/vfio_platform.c
> +++ b/drivers/vfio/platform/vfio_platform.c
> @@ -108,6 +108,7 @@ static const struct vfio_device_ops vfio_platform_ops = {
>  	.bind_iommufd	= vfio_iommufd_physical_bind,
>  	.unbind_iommufd	= vfio_iommufd_physical_unbind,
>  	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
> +	.detach_ioas	= vfio_iommufd_physical_detach_ioas,
>  };
>  
>  static struct platform_driver vfio_platform_driver = {
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 39d552e5160b..599d551fc4b5 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -273,7 +273,8 @@ static int __vfio_register_dev(struct vfio_device *device,
>  	if (WARN_ON(IS_ENABLED(CONFIG_IOMMUFD) &&
>  		    (!device->ops->bind_iommufd ||
>  		     !device->ops->unbind_iommufd ||
> -		     !device->ops->attach_ioas)))
> +		     !device->ops->attach_ioas ||
> +		     !device->ops->detach_ioas)))
>  		return -EINVAL;
>  
>  	/*
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 431eb82e0595..f446f5901e46 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -74,7 +74,9 @@ struct vfio_device {
>   * @bind_iommufd: Called when binding the device to an iommufd
>   * @unbind_iommufd: Opposite of bind_iommufd
>   * @attach_ioas: Called when attaching device to an IOAS/HWPT managed by the
> - *		 bound iommufd. Undo in unbind_iommufd.
> + *		 bound iommufd. Undo in unbind_iommufd if @detach_ioas is not
> + *		 called.
> + * @detach_ioas: Opposite of attach_ioas
>   * @open_device: Called when the first file descriptor is opened for this device
>   * @close_device: Opposite of open_device
>   * @read: Perform read(2) on device file descriptor
> @@ -98,6 +100,7 @@ struct vfio_device_ops {
>  				struct iommufd_ctx *ictx, u32 *out_device_id);
>  	void	(*unbind_iommufd)(struct vfio_device *vdev);
>  	int	(*attach_ioas)(struct vfio_device *vdev, u32 *pt_id);
> +	void	(*detach_ioas)(struct vfio_device *vdev);
>  	int	(*open_device)(struct vfio_device *vdev);
>  	void	(*close_device)(struct vfio_device *vdev);
>  	ssize_t	(*read)(struct vfio_device *vdev, char __user *buf,
> @@ -121,6 +124,7 @@ int vfio_iommufd_physical_bind(struct vfio_device *vdev,
>  			       struct iommufd_ctx *ictx, u32 *out_device_id);
>  void vfio_iommufd_physical_unbind(struct vfio_device *vdev);
>  int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id);
> +void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev);
>  int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
>  			       struct iommufd_ctx *ictx, u32 *out_device_id);
>  void vfio_iommufd_emulated_unbind(struct vfio_device *vdev);
> @@ -145,6 +149,8 @@ vfio_iommufd_physical_devid(struct vfio_device *vdev)
>  	((void (*)(struct vfio_device *vdev)) NULL)
>  #define vfio_iommufd_physical_attach_ioas \
>  	((int (*)(struct vfio_device *vdev, u32 *pt_id)) NULL)
> +#define vfio_iommufd_physical_detach_ioas \
> +	((void (*)(struct vfio_device *vdev)) NULL)
>  #define vfio_iommufd_emulated_bind                                      \
>  	((int (*)(struct vfio_device *vdev, struct iommufd_ctx *ictx,   \
>  		  u32 *out_device_id)) NULL)