Re: [PATCH v3 5/6] x86/bugs: Don't fill RSB on context switch with eIBRS

[Nikolay Borisov]

On 2.04.25 г. 21:19 ч., Josh Poimboeuf wrote:
> User->user Spectre v2 attacks (including RSB) across context switches
> are already mitigated by IBPB in cond_mitigation(), if enabled globally
> or if either the prev or the next task has opted in to protection.  RSB
> filling without IBPB serves no purpose for protecting user space, as
> indirect branches are still vulnerable.
>
> User->kernel RSB attacks are mitigated by eIBRS.  In which case the RSB
> filling on context switch isn't needed, so remove it.
>
> Suggested-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
> Reviewed-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
> Reviewed-by: Amit Shah <amit.shah@xxxxxxx>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx>