RE: [PATCH v2 0/5] iommu: Enable user space IOPFs in non-PASID and non-svm cases

[Tian, Kevin]

> From: Joel Granados <j.granados@xxxxxxxxxxx>
> Sent: Monday, September 16, 2024 4:51 PM
> 
> On Sat, Sep 14, 2024 at 12:48:31AM +0000, Tian, Kevin wrote:
> > > From: Joel Granados via B4 Relay
> > > <devnull+j.granados.samsung.com@xxxxxxxxxx>
> > >
> > > This series makes use of iommufd_hwpt_replace_device to execute
> > > non-pasid/non-svm user space IOPFs. Our main motivation is to enable
> > > user-space driver driven device verification without SVM/PASID.
> >
> > can you elaborate why IOPFs are necessary to help verify such usage?
> 
> In retrospect "enable" might not be the best word to use here. We are not
> "enabling" user-space driver driven device verification as it is already
> enabled; you could already poke a device from user space. But the whole
> poke
> space was not available, you could not test IOPF without having an
> SVM/PASID
> capable IOMMU. Therefore a better wording would be "Our main motivation
> is to
> expand or facilitate user-space driver driven device verification by enabling
> IOPF without SMV/PASID".
> 

hmm did you actually see a IOMMU which supports IOPF only but
not SVM/PASID? 

this series alone has its merit, e.g. postcopy migration might want
such notification. But not sure it helps solve a real problem in your side...