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

Liu, Yi L
2023-04-21T07:12:08Z

> From: Alex Williamson <alex.williamson@redhat.com>
> Sent: Wednesday, April 5, 2023 5:49 AM
> 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

This may be a user-triggerable warning if the input device is not bound
to iommufd.

> 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,

Ok. then it can return invalid id when !CONFIG_IOMMUFD. Also
Needs to wait for the decision in the thread that is talking errr-code.

Regards,
Yi Liu

> 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
> >