Re: [PATCH v3 21/22] iommu/amd: Add translation DTE and VFctrl TransDevID helpers

[Suthikulpanit, Suravee]

On 7/7/2026 9:43 PM, Jason Gunthorpe wrote:
> On Mon, Jun 29, 2026 at 03:35:34PM +0000, Suravee Suthikulpanit wrote:
> > The hardware vIOMMU uses a per-VM translate device ID (TransDevID)
> > to
>
> per-viommu, the iommu drivers don't work with the concept of VM.

Updating this in v4

> > index the host device table when guest IOMMU traffic needs GPA->SPA
> > translation.  The VF Control guest miscellaneous register tells the
> > IOMMU which TransDevID to use; the corresponding device table entry
> > (DTE) points at the nested IOMMU v1 page table that performs the walk
> > from guest physical to system physical addresses.
>
> A v1 page table is a "parent" not a nested

Updating this in v4

> > @@ -213,7 +213,12 @@ void amd_iommu_update_dte(struct amd_iommu *iommu,
> >   			     struct dev_table_entry *new)
> >   {
> >   	update_dte256(iommu, dev_data, new);
> > -	clone_aliases(iommu, dev_data->dev);
> > +	/*
> > +	 * The dev_data for trans_devid does not have struct dev.
> > +	 * So clone_aliases is not supported for translate-device-id.
> > +	 */
> > +	if (dev_data->dev)
> > +		clone_aliases(iommu, dev_data->dev);
>
> More junk from the ugly alias scheme :\ Maybe you should fix it

I will have a separate series to clean up all alias stuff after this series.

> > +int amd_iommu_set_translate_dte(struct amd_iommu *iommu,
> > +				 struct protection_domain *pdom,
> > +				 u16 gid, u32 trans_devid)
> > +{
>
> This should probably accept a viommu struct instead of all these arguments.

Note. I'll update this in v4.

Thanks,
Suravee