Re: [PATCH v3 12/13] PCI/TSM: support TDI related operations for host TSM driver

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, May 29, 2025 at 07:13:54PM +0530, Aneesh Kumar K.V wrote:
> Jason Gunthorpe <jgg@nvidia.com> writes:
> 
> > On Wed, May 28, 2025 at 01:42:25PM -0300, Jason Gunthorpe wrote:
> >> > +int iommufd_vdevice_tsm_bind_ioctl(struct iommufd_ucmd *ucmd)
> >> > +{
> >> > +	struct iommu_vdevice_id *cmd = ucmd->cmd;
> >> > +	struct iommufd_vdevice *vdev;
> >> > +	int rc = 0;
> >> > +
> >> > +	vdev = container_of(iommufd_get_object(ucmd->ictx, cmd->vdevice_id,
> >> > +					       IOMMUFD_OBJ_VDEVICE),
> >> > +			    struct iommufd_vdevice, obj);
> >> > +	if (IS_ERR(vdev))
> >> > +		return PTR_ERR(vdev);
> >> > +
> >> > +	rc = tsm_bind(vdev->dev, vdev->viommu->kvm, vdev->id);
> >> 
> >> Yeah, that makes alot of sense now, you are passing in the KVM for the
> >> VIOMMU and both the vBDF and pBDF to the TSM layer, that should be
> >> enough for it to figure out what to do. The only other data would be
> >> the TSM's VIOMMU handle..
> >
> > Actually it should also check that the viommu type is compatible with
> > the TSM, somehow.
> >
> > The way I imagine this working is userspace would create a 
> > IOMMU_VIOMMU_TYPE_TSM_VTD (for example) viommu object which will do a
> > TSM call to setup the secure vIOMMU
> >
> > Then when you create a VDEVICE against the IOMMU_VIOMMU_TYPE_TSM_VTD
> > it will do a TSM call to create the secure vPCI function attached to
> > the vIOMMU and register the vBDF. [1]
> >
> 
> Don’t we create the vdevice before the guest starts? 

Yes, vdevice/vPCI creation is before the guest start.

> If I understand correctly, we expect tsm_bind to be triggered by the
> guest’s request—specifically, when it writes to
> /sys/bus/pci/devices/X/tsm/connect.

Yes, vdevice creation does not set the device to T=1.

If the device is T=1/0 mode is a dynamic choice controlled by the
guest.

vPCI device creation is controlled by the hypervisor and is done
before starting the VM. It just informs the TSM that a vPCI function
exists, should the TSM need to know that, which it usually will if
a secure vIOMMU is involved.

Jason