Re: [PATCH v12 0/6] iommu/dma: s390 DMA API conversion and optimized IOTLB flushing

Niklas Schnelle
2023-09-27T08:56:29Z

On Tue, 2023-09-26 at 13:08 -0300, Jason Gunthorpe wrote:
> On Tue, Sep 26, 2023 at 05:04:28PM +0200, Joerg Roedel wrote:
> > Hi Niklas,
> >
> > On Fri, Aug 25, 2023 at 12:11:15PM +0200, Niklas Schnelle wrote:
> > > Niklas Schnelle (6):
> > > iommu: Allow .iotlb_sync_map to fail and handle s390's -ENOMEM return
> > > s390/pci: prepare is_passed_through() for dma-iommu
> > > s390/pci: Use dma-iommu layer
> > > iommu/s390: Disable deferred flush for ISM devices
> > > iommu/dma: Allow a single FQ in addition to per-CPU FQs
> > > iommu/dma: Use a large flush queue and timeout for shadow_on_flush
> >
> > Turned out this series has non-trivial conflicts with Jasons
> > default-domain work so I had to remove it from the IOMMU tree for now.
> > Can you please rebase it to the latest iommu/core branch and re-send? I
> > will take it into the tree again then.
>
> Niklas, I think you just 'take yours' to resolve this. All the
> IOMMU_DOMAIN_PLATFORM related and .default_domain = parts should be
> removed. Let me know if you need anything
>
> Thanks,
> Jason

Hi Joerg, Hi Jason,

I've run into an unfortunate problem, not with the rebase itself but
with the iommu/core branch.

Jason is right, I basically need to just remove the platform ops and
.default_domain ops. This seems to work fine for an NVMe both in the
host and also when using the IOMMU with vfio-pci + KVM. I've already
pushed the result of that to my git.kernel.org:
https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git/log/?h=b4/dma_iommu

The problem is that something seems to be broken in the iommu/core
branch. Regardless of whether I have my DMA API conversion on top or
with the base iommu/core branch I can not use ConnectX-4 VFs.

# lspci
111a:00:00.0 Ethernet controller: Mellanox Technologies MT27710 Family [ConnectX-4 Lx Virtual Function]
# dmesg | grep mlx
[ 3.189749] mlx5_core 111a:00:00.0: mlx5_mdev_init:1802:(pid 464): Failed initializing cmdif SW structs, aborting
[ 3.189783] mlx5_core: probe of 111a:00:00.0 failed with error -12

This same card works on v6.6-rc3 both with and without my DMA API
conversion patch series applied. Looking at mlx5_mdev_init() ->
mlx5_cmd_init(). The -ENOMEM seems to come from the following
dma_pool_create():

cmd->pool = dma_pool_create("mlx5_cmd", mlx5_core_dma_dev(dev), size, align, 0);

I'll try to debug this further but wanted to let you know already in
case you have some ideas. Either way as it doesn't seem to be related
to the DMA API conversion I can sent that out again regardless if you
want, really don't want to miss another cycle.

Thanks,
Niklas