Re: [tip: x86/urgent] x86/CPU/AMD: Add RDSEED fix for Zen5

From: Jason A. Donenfeld

Date: Thu Oct 30 2025 - 14:05:25 EST


Hi,

On Tue, Oct 28, 2025 at 12:01:51PM -0000, tip-bot2 for Gregory Price wrote:
> x86/CPU/AMD: Add RDSEED fix for Zen5
>
> There's an issue with RDSEED's 16-bit and 32-bit register output
> variants on Zen5 which return a random value of 0 "at a rate inconsistent
> with randomness while incorrectly signaling success (CF=1)". Search the
> web for AMD-SB-7055 for more detail.
>
> Add a fix glue which checks microcode revisions.
>
> [ bp: Add microcode revisions checking, rewrite. ]
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Gregory Price <gourry@xxxxxxxxxx>
> Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
> Link: https://lore.kernel.org/r/20251018024010.4112396-1-gourry@xxxxxxxxxx

I didn't see this on LKML or any mailing list before this appeared in
tip. Did I miss something?

Jason