Re: Request to port to 6.6.y : c809b0d0e52d ("x86/microcode/AMD: Flush patch buffer mapping after application")

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Dec 17, 2024 at 04:32:55PM +0100, Thomas De Schampheleire wrote:
> Hello,
> 
> Below commit was ported to 6.12, but I would like to request porting to the 6.6
> longterm branch we are currently using:
> 
>     commit c809b0d0e52d01c30066367b2952c4c4186b1047
>     Author: Borislav Petkov (AMD) <bp@alien8.de>
>     Date:   2024-11-19 12:21:33 +0100
> 
>         x86/microcode/AMD: Flush patch buffer mapping after application
>         [...]
> 
> 
> The patch itself is small, but the consequence of not patching is large on
> affected systems (tens of seconds to minutes, of boot delay). See original
> discussion [1] for details.
> 
> The patch in master relies on a variable 'bsp_cpuid_1_eax' introduced in commit
> 94838d230a6c ("x86/microcode/AMD: Use the family,model,stepping encoded in the
> patch ID"), but porting that entire commit seems excessive, especially because
> there are several 'Fixes' commits for that one (e.g. 5343558a868e, d1744a4c975b,
> 1d81d85d1a19).
> 
> I think the simplest prerequisite change is (for Borislav Petkov to confirm):

Please send a set of working, and tested, commits that you wish for us
to commit, we can't cherry-pick stuff out of an email like this for
obvious reasons :)

And whenever possible, yes, we do want to take the fixes that are in
Linus's tree, otherwise maintaining the branch over time gets harder and
harder.  So just backport them all please.

thanks,

greg k-h