Re: [PATCH v4 3/3] iommu: Drop sw_msi from iommu_domain

[Nicolin Chen <nicolinc@nvidia.com>]

On Mon, Mar 24, 2025 at 01:40:23PM -0300, Jason Gunthorpe wrote:
> On Mon, Mar 24, 2025 at 09:25:58AM -0700, Nathan Chancellor wrote:
> 
> > I bisected a loss of networking on one of my machines to this change as
> > commit e009e088d88e ("iommu: Drop sw_msi from iommu_domain") in -next.
> 
> Okay wow, I will drop this series from the tree if I don't see a
> resolution in a few days. We can try again next cycle, thank you for
> testing and bisect!
> 
> > At this change, I see:
> > 
> >   [  +0.000000] Linux version 6.14.0-rc2-00033-ge009e088d88e (nathan@ax162) (aarch64-linux-gcc (GCC) 14.2.0, GNU ld (GNU Binutils) 2.42) #1 SMP PREEMPT_DYNAMIC Mon Mar 24 08:57:49 MST 2025
> >   ...
> >   [  +0.002355] fsl_mc_bus NXP0008:00: Adding to iommu group 0
> >   [  +0.000533] fsl_mc_bus NXP0008:00: MC firmware version: 10.28.1
> >   [  +0.002565] fsl_mc_dprc dprc.1: DMA mask not set
> >   [  +0.019255] fsl_mc_dprc dprc.1: Adding to iommu group 1
> >   [  +0.046820] fsl_mc_dprc dprc.1: Failed to allocate IRQs
> 
> I guess it is tripping up going through iommu_dma_prepare_msi()
> somehow?
> 
> Maybe fsl bus is special and doesn't manage to set
> IOMMU_COOKIE_DMA_IOVA for some reason?
> 
> I wonder if this is not right:
> 
> +               default:
> +                       ret = -EOPNOTSUPP;
> +                       break;
> 
> And it should be just break instead (return 0) which is what was
> happening before?

Yea, I found the diff here too.

Nathan, would you please give it a try by removing this
	ret = -EOPNOTSUPP;
?

Thanks
Nicolin