S390 testing for IOMMUFD

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Nov 07, 2022 at 08:48:53PM -0400, Jason Gunthorpe wrote:
> [
> This has been in linux-next for a little while now, and we've completed
> the syzkaller run. 1300 hours of CPU time have been invested since the
> last report with no improvement in coverage or new detections. syzkaller
> coverage reached 69%(75%), and review of the misses show substantial
> amounts are WARN_ON's and other debugging which are not expected to be
> covered.
> ]
> 
> iommufd is the user API to control the IOMMU subsystem as it relates to
> managing IO page tables that point at user space memory.

[chop cc list]

s390 mdev maintainers,

Can I ask your help to test this with the two S390 mdev drivers? Now
that gvt is passing and we've covered alot of the QA ground it is a
good time to run it.

Take the branch from here:

https://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd.git/log/?h=for-next

And build the kernel with 

CONFIG_VFIO_CONTAINER=n
CONFIG_IOMMUFD=y
CONFIG_IOMMUFD_VFIO_CONTAINER=y

And your existing stuff should work with iommufd providing the iommu
support to vfio. There will be a dmesg confirming this.

Let me know if there are any problems!

If I recall there was some desire from the S390 platform team to start
building on iommufd to create some vIOMMU acceleration for S390
guests, this is a necessary first step.

Thanks,
Jason