Re: [PATCH v2 02/14] iommufd: Extend attach/detach_hwpt callbacks to support pasid

[Nicolin Chen via <qemu-arm@nongnu.org>]

On Fri, Mar 27, 2026 at 10:34:01AM +0100, Cédric Le Goater wrote:
> On 3/27/26 07:44, Duan, Zhenzhong wrote:
> > 
> > 
> > > -----Original Message-----
> > > From: Nicolin Chen <nicolinc@nvidia.com>
> > > Subject: Re: [PATCH v2 02/14] iommufd: Extend attach/detach_hwpt callbacks to
> > > support pasid
> > > 
> > > On Fri, Mar 27, 2026 at 02:32:57AM +0000, Duan, Zhenzhong wrote:
> > > > > -----Original Message-----
> > > > > From: Nicolin Chen <nicolinc@nvidia.com>
> > > > > Subject: Re: [PATCH v2 02/14] iommufd: Extend attach/detach_hwpt callbacks
> > > to
> > > > > support pasid
> > > > > 
> > > > > On Thu, Mar 26, 2026 at 05:11:16AM -0400, Zhenzhong Duan wrote:
> > > > > > @@ -138,14 +138,16 @@ struct HostIOMMUDeviceIOMMUFDClass {
> > > > > >        *
> > > > > >        * @idev: host IOMMU device backed by IOMMUFD backend.
> > > > > 
> > > > > Not commenting against this patch, but I just found the "host IOMMU
> > > > > device" and the "HostIOMMUDeviceIOMMUFD" a bit ambiguous. It's not
> > > > > an "IOMMU device" right? Perhaps somebody can help me understand :)
> > > > 
> > > > A host device under host IOMMU?
> > > 
> > > "host device" would make sense, not "host IOMMU device", right?
> > 
> > We want to emphasize that it's a "host device" backed by "host IOMMU",
> > "host device" is not enough, I think.
> Yes. These are related to the Host IOMMU device backends :
> 
>   - VFIO IOMMU Type1, a.k.a legacy backend
>   - IOMMUFD,
> 
> There are other implementations. VFIO IOMMU Type1 is versioned and
> a ppc flavor exists.

But the @idev here is a passthrough device (VFIO/PCI)?

"IOMMU device" would be SMMU, VT-d...

Especially we are adding @pasid parameter. Relating it to SMMU or
VT-d sounds weird.

Nicolin