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

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> From: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Sent: Tuesday, May 23, 2023 4:59 AM
> 
> On Mon, 22 May 2023 14:46:17 -0600
> Alex Williamson <alex.williamson@xxxxxxxxxx> wrote:
> 
> > On Sat, 13 May 2023 06:28:17 -0700
> > Yi Liu <yi.l.liu@xxxxxxxxx> wrote:
> >
> > > this prepares for adding DETACH ioctl for physical VFIO devices.
> > >
> > > 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>
> > > Tested-by: Yanting Jiang <yanting.jiang@xxxxxxxxx>
> > > Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> > > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> > > ---
> > >  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,
> 
> Oops, didn't track the close paren correctly, disregard.  Thanks,

Not sure ill it be clearer to have !vdev->iommufd_attached in the next
line? 😊

Regards,
Yi Liu

> 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)
> >





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