Re: [RFC PATCH v4 00/16] coco/TSM: Implement host-side support for Arm CCA TDISP setup

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Apr 27, 2026 at 02:23:28PM +0530, Aneesh Kumar K.V (Arm) wrote:
> 
> This patch series implements the host-side changes needed for end-to-end
> Arm CCA TDISP setup. It adds the RMI/RHI plumbing required to create and
> manage Realm vdev objects, service device-attestation object requests, and
> complete the KVM/RMM flows needed for device run-time transitions.

So this is enough for the realm to see a physical PCI device inside it
without any vSMMU inside the realm?

It is really weird to see a viommu for a case where there is no
viommu..

It doesn't do anything except manage memory for the RMM..

It feels wrong that the arm-cca-guest module is calling
RMI_PDEV_CREATE and RMI_VDEV_CREATE while the viommu is allocating STE
memory for the PDEV. That doesn't make alot of sense? The STE is
needed before VDEV_CREATE, right? So why not place it there in the
flow?

If that's changed then the only thing the viommu does is manage the
PSMMU, which again, seems like something VDEV_CREATE needs, so why is
a viommu involved at all?

The smmu driver involvment would be much smaller if it was only the
interrupt routing and some helper to return the psmmu addr for a
struct device that the arm-cc-guest module can call to manage the
psmmu?

But I'm also sitting here scratching my head a bit, did the tsm_ops
design go the wrong way? Should we have run more of that through a
viommu instead of tsm_ops? Bind is sort of an illogical operation
without a viommu, even if it is a nop viommu.

I suppose it depends what it looks like when a real vsmmu is
created.. That probably needs a special viommu object, and do we get
into order problems if the lifecylce becomes split to tsm and viommu?

> RHI v1.0 BET1 specification [5].
> 
> At a high level, the series adds support for:
> - host-side vdev communication and lifecycle management
> - host handling of RHI DA object read/size requests
> - host-side fetching and caching of interface reports and measurements
> - KVM handling of vdev request/complete exits
> - KVM handling of map/validation exits and teardown on granule destroy
> - vdev transition to TDISP RUN state
> - enabling DA in Realm create parameters
> 
> The series builds upon the TSM framework patches posted at [2] and depends on
> the KVM CCA patchset [3]. A git repository containing all related changes is
> available at [4]. kvmtool repo is at [6]

It looks like it also needs the series that adds bind to iommufd too

Jason