Re: [PATCH v3 0/6] x86/hygon: Add Family 0x18 DF node enumeration and SMN access

[Yazen Ghannam]

On Wed, Jul 22, 2026 at 12:59:13PM -0700, Borislav Petkov wrote:
> On Thu, Jul 09, 2026 at 03:55:43PM +0800, Lin Wang wrote:
> > Hygon Family 0x18 systems expose Data Fabric (DF) devices in a layout
> > that cannot be handled by the AMD fixed-slot node model.
> 
> A bunch of issues Sashiko caught which need addressing:
> 
> https://sashiko.dev/#/patchset/20260709075549.626095-1-wanglin%40open-hieco.net
> 
> @Yazen, there are some preexisting ones in the SMN code that would need
> addressing/commenting too.
> 

There are a couple of preexisting issues.

1) Use-After-Free

This looks like a long-time gap that doesn't happen in practice. The
"devices" are the internal root ports. They don't get added/removed,
since they're built into the chip. And the amd_node code is built-in
too.

In any case, I'll work on a patch for this.

2) Divide-by-Zero

This one has come up a few times recently. Latest two threads:

https://lore.kernel.org/20260506055528.476493-1-penny.zheng@xxxxxxx/
https://lore.kernel.org/20260623211904.3674-1-jason.andryuk@xxxxxxx/

Thanks,
Yazen