Re: S390 testing for IOMMUFD

Christian Borntraeger
2022-11-08T10:13:30Z

Am 08.11.22 um 02:09 schrieb Jason Gunthorpe:
> 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.

Gave it a quick spin with vfio_ap:
[ 401.679199] vfio_ap_mdev b01a7c33-9696-48b2-9a98-050e8e17c69a: Adding to iommu group 1
[ 402.085386] iommufd: IOMMUFD is providing /dev/vfio/vfio, not VFIO.

Some tests seem to work, but others dont (running into timeouts). I need to look
into that (or ideally Tony will have a look, FWIW tests.test_vfio_ap.VfioAPAssignMdevToGuestTest
fails for me.

The same kernel tree with defconfig (instead of CONFIG_IOMMUFD_VFIO_CONTAINER=y) works fine.
>
> 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