Re: [Xen-devel] [PATCH V2] x86, amd_ucode: Skip microcode updates for final levels

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 03/08/15 17:35, Aravind Gopalakrishnan wrote:
> Some of older[Fam10h] systems require that certain number of
> applied microcode patch levels should not be overwritten by
> the microcode loader. Otherwise, system hangs are known to occur.
>
> The 'final_levels' of patch ids have been obtained empirically.
> Refer bug https://bugzilla.suse.com/show_bug.cgi?id=913996
> for details of the issue.
>
> The short version is that people have predominantly noticed
> system hang issues when trying to update microcode levels
> beyond the patch IDs below.
> [0x01000098, 0x0100009f, 0x010000af]
>
> From internal discussions, we gathered that OS/hypervisor
> cannot reliably perform microcode updates beyond these levels
> due to hardware issues. Therefore, we need to abort microcode
> update process if we hit any of these levels.
>
> In this patch, we check for those microcode versions and abort
> if the current core has one of those final patch levels applied
> by the BIOS
>
> A linux version of the patch has already made it into tip-
> http://marc.info/?l=linux-kernel&m=143703405627170
>
> Signed-off-by: Aravind Gopalakrishnan <aravind.gopalakrishnan@xxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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