Re: [PATCH v2 0/4] Firmware LSM hook

Leon Romanovsky
2026-04-27T19:09:46Z

On Sun, Apr 26, 2026 at 10:42:24AM -0300, Jason Gunthorpe wrote:
> On Sun, Apr 26, 2026 at 01:39:57PM +0300, Leon Romanovsky wrote:
> > On Fri, Apr 24, 2026 at 11:19:21AM -0300, Jason Gunthorpe wrote:
> > > On Thu, Apr 23, 2026 at 05:09:50PM +0300, Leon Romanovsky wrote:
> > >
> > > > > > Leon mentioned that different firmware revisions would have different
> > > > > > parameters for a given opcode, and that one would need to inspect
> > > > > > those parameters to properly filter the command. Is that not true, or
> > > > > > am I misreading or misunderstanding Leon's comments?
> > > > >
> > > > > They are ABI stable, so there will be rules about future changes that
> > > > > old software can follow to ignore or reject future things it doesn't
> > > > > understand.
> > > >
> > > > It is wishful thinking and applicable only to mlx5 devices. No one
> > > > promises that other devices follow same ABI rules.
> > >
> > > Well, I will definately kick them out of fwctl if they don't.
> >
> > It is easy to say but harder to follow. The kernel includes many devices that
> > exist only in specific hyperscale environments, where the update cycle is
> > tightly controlled. They easily can break FW backward compatibility.
>
> Well Linus's rule applies here, if it doesn't bother anyone it didn't
> break..

Great, that means they can load any BPF program they want and access whatever
firmware fields they choose. Your earlier claim about 'not breaking FW
compatibility' is only partially correct.

Thanks

>
> Jason
>