Re: [PATCH v3 04/12] vfio-iommufd: Add helper to retrieve iommufd_ctx and devid for vfio_device

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

On Tue, 4 Apr 2023 17:28:40 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> Hi,
> 
> On 4/1/23 16:44, Yi Liu wrote:
> > This is needed by the vfio-pci driver to report affected devices in the
> > hot reset for a given device.
> >
> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> > Tested-by: Yanting Jiang <yanting.jiang@intel.com>
> > Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> > ---
> >  drivers/iommu/iommufd/device.c | 12 ++++++++++++
> >  drivers/vfio/iommufd.c         | 14 ++++++++++++++
> >  include/linux/iommufd.h        |  3 +++
> >  include/linux/vfio.h           | 13 +++++++++++++
> >  4 files changed, 42 insertions(+)
> >
> > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> > index 25115d401d8f..04a57aa1ae2c 100644
> > --- a/drivers/iommu/iommufd/device.c
> > +++ b/drivers/iommu/iommufd/device.c
> > @@ -131,6 +131,18 @@ void iommufd_device_unbind(struct iommufd_device *idev)
> >  }
> >  EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD);
> >  
> > +struct iommufd_ctx *iommufd_device_to_ictx(struct iommufd_device *idev)
> > +{
> > +	return idev->ictx;
> > +}
> > +EXPORT_SYMBOL_NS_GPL(iommufd_device_to_ictx, IOMMUFD);
> > +
> > +u32 iommufd_device_to_id(struct iommufd_device *idev)
> > +{
> > +	return idev->obj.id;
> > +}
> > +EXPORT_SYMBOL_NS_GPL(iommufd_device_to_id, IOMMUFD);
> > +
> >  static int iommufd_device_setup_msi(struct iommufd_device *idev,
> >  				    struct iommufd_hw_pagetable *hwpt,
> >  				    phys_addr_t sw_msi_start)
> > diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
> > index 88b00c501015..809f2dd73b9e 100644
> > --- a/drivers/vfio/iommufd.c
> > +++ b/drivers/vfio/iommufd.c
> > @@ -66,6 +66,20 @@ void vfio_iommufd_unbind(struct vfio_device *vdev)
> >  		vdev->ops->unbind_iommufd(vdev);
> >  }
> >  
> > +struct iommufd_ctx *vfio_iommufd_physical_ictx(struct vfio_device *vdev)
> > +{
> > +	if (!vdev->iommufd_device)
> > +		return NULL;
> > +	return iommufd_device_to_ictx(vdev->iommufd_device);
> > +}
> > +EXPORT_SYMBOL_GPL(vfio_iommufd_physical_ictx);
> > +
> > +void vfio_iommufd_physical_devid(struct vfio_device *vdev, u32 *id)
> > +{
> > +	if (vdev->iommufd_device)
> > +		*id = iommufd_device_to_id(vdev->iommufd_device);  
> since there is no return value, may be worth to add at least a WARN_ON
> in case of !vdev->iommufd_device

Yeah, this is bizarre and makes the one caller of this interface very
awkward.  We later go on to define IOMMUFD_INVALID_ID, so this should
simply return that in the case of no iommufd_device and skip this
unnecessary pointer passing.  Thanks,

Alex

> > +}
> > +EXPORT_SYMBOL_GPL(vfio_iommufd_physical_devid);
> >  /*
> >   * The physical standard ops mean that the iommufd_device is bound to the
> >   * physical device vdev->dev that was provided to vfio_init_group_dev(). Drivers
> > diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
> > index 1129a36a74c4..ac96df406833 100644
> > --- a/include/linux/iommufd.h
> > +++ b/include/linux/iommufd.h
> > @@ -24,6 +24,9 @@ void iommufd_device_unbind(struct iommufd_device *idev);
> >  int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id);
> >  void iommufd_device_detach(struct iommufd_device *idev);
> >  
> > +struct iommufd_ctx *iommufd_device_to_ictx(struct iommufd_device *idev);
> > +u32 iommufd_device_to_id(struct iommufd_device *idev);
> > +
> >  struct iommufd_access_ops {
> >  	u8 needs_pin_pages : 1;
> >  	void (*unmap)(void *data, unsigned long iova, unsigned long length);
> > diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> > index 3188d8a374bd..97a1174b922f 100644
> > --- a/include/linux/vfio.h
> > +++ b/include/linux/vfio.h
> > @@ -113,6 +113,8 @@ struct vfio_device_ops {
> >  };
> >  
> >  #if IS_ENABLED(CONFIG_IOMMUFD)
> > +struct iommufd_ctx *vfio_iommufd_physical_ictx(struct vfio_device *vdev);
> > +void vfio_iommufd_physical_devid(struct vfio_device *vdev, u32 *id);
> >  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);
> > @@ -122,6 +124,17 @@ int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
> >  void vfio_iommufd_emulated_unbind(struct vfio_device *vdev);
> >  int vfio_iommufd_emulated_attach_ioas(struct vfio_device *vdev, u32 *pt_id);
> >  #else
> > +static inline struct iommufd_ctx *
> > +vfio_iommufd_physical_ictx(struct vfio_device *vdev)
> > +{
> > +	return NULL;
> > +}
> > +
> > +static inline void
> > +vfio_iommufd_physical_devid(struct vfio_device *vdev, u32 *id)
> > +{
> > +}
> > +
> >  #define vfio_iommufd_physical_bind                                      \
> >  	((int (*)(struct vfio_device *vdev, struct iommufd_ctx *ictx,   \
> >  		  u32 *out_device_id)) NULL)  
> besides
> 
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> 
> Eric
>