Re: [PATCH 2/2] x86/bugs: Don't WARN() when overwriting retbleed_return_thunk with srso_return_thunk

[Borislav Petkov]

On Fri, May 16, 2025 at 03:18:30PM +0000, Kaplan, David wrote:
> Hmm.  Since SRSO is kind of a superset of retbleed, it might make sense to
> create a new mitigation, RETBLEED_MITIGATION_SAFE_RET.
> 
> retbleed_update_mitigation() can change its mitigation to this if
> srso_mitigation is SAFE_RET (or SAFE_RET_UCODE_NEEDED).
> RETBLEED_MITIGATION_SAFE_RET can do nothing in retbleed_apply_mitigation()
> because it means that srso is taking care of things.  Thoughts?
> 
> This also made me realize there's another minor missing interaction here,
> which is that if spec_rstack_overflow=ibpb, then that should set
> retbleed_mitigation to IBPB as well.

Ok, this sounds like we should expedite our srso mitigation cleanup
intentions. :-)

Lemme find you on chat...

-- 
Regards/Gruss,
    Boris.

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