Re: [PATCH RFC PREVIEW 0/6] iommu: enable user space iopfs in non-nested and non-svm cases

[Joel Granados]

On Wed, Sep 04, 2024 at 01:13:50PM -0300, Jason Gunthorpe wrote:
> On Mon, Sep 02, 2024 at 12:48:19PM +0200, Joel Granados wrote:
> > > >   Supplementary repositories supporting this patchset:
> > > >     1. A user space library libvfn [1] which is used for testing and
> > > >        verification (see examples/iopf.c), and
> > > 
> > > That's pretty neat, I've been wanting to see some kind of IOMMU test
> > > suite based around a capable widely available device. This is the
> > > closest I've seen..
> >
> > Yes! This is an obvious application of libvfn. Do you see it as a
> > something that can be included in tools/selftests/iommu?
> 
> Maybe? What would it look like in-kernel?
Having it in-kernel with libvfn might be a bit too much because we would
have to bring libvfn into the kernel sources. But we can have some sort
of DMA test suit that runs as CI. Similar to what fstests or blktest do
(dmatests?). And we can automate it all with kdevops.

Here is a very rough run down of the idea.
1. We create (or use if there is one already) a DMA test suit. That has
can run on its own
2. Use libvfn to create commands that poke at the iommu{,fd}, intel)
amd, arm drivers.
3. Use qemu iommu implementation as well as pci dma enabled devices as
the test devices.
4. Can use hardware if it is detected.
5. Can use kdevops to bring up the different environments (e.g. kernel and
qemu branch combinations) needed for the test.
6. And finally put the kdevops test targets into some existing kernel CI
like linux-next or 0day (or whatever makes sense).

> 
> I've been thinking the same thing with mlx5
Not too familiar with this driver, but if it makes sense to reuse it (or
part of it) to make the test happen, I'm all for that.

> 
> Maybe some kind of test runner with a plugin driver that has some kind
> of 'do dma', 'generate interrupt', etc sort of operations, IDK.
Yes. If you are up for it, we can maybe discuss it a bit in LPC and
flesh it out a bit more?

Best

-- 

Joel Granados