Re: [PATCH v2 00/17] Solve iommu probe races around iommu_fwspec

Jason Gunthorpe
2023-11-15T15:36:26Z

On Wed, Nov 15, 2023 at 03:22:09PM +0000, Robin Murphy wrote:
> On 2023-11-15 2:05 pm, Jason Gunthorpe wrote:
> > [Several people have tested this now, so it is something that should sit in
> > linux-next for a while]
>
> What's the aim here? This is obviously far, far too much for a
> stable fix,

To fix the locking bug and ugly abuse of dev->iommu?

I wouldn't say that, it is up to the people who care about this to
decide. It seems alot of people are hitting it so maybe it should be
backported in some situations. Regardless, we should not continue to
have this locking bug in v6.8.

> but then it's also not the refactoring we want for the future either, since
> it's moving in the wrong direction of cementing the fundamental brokenness
> further in place rather than getting any closer to removing it.

I haven't seen patches or an outline on what you have in mind though?

In my view I would like to get rid of of_xlate(), at a minimum. It is
a micro-optimization I don't think we need. I see a pretty
straightforward path to get there from here.

Do you also want to get rid of iommu_fwspec, or at least thin it out?
That seems reasonable too, I think that becomes within reach once
of_xlate is gone.

What do you see as "cemeting"?

Jason