Re: [PATCH v2] x86/microcode/intel: Taint kernel on partial update

[Nikolay Borisov]

On 7/9/26 00:18, Chang S. Bae wrote:
> A modern individual microcode update contains firmware for many pieces of
> silicon inside the CPU. Sometimes, a single update operation successfully
> updates some components and not others leaving a partially-applied
> update.
>
> This may leave the system in an undefined and unreliable state. Fatal
> failures are expected to be handled by the CPU itself, by raising #MC for
> example. If the CPU instead reports a partial update, warn and taint the
> kernel at least.
>
> A partial update may still update the revision. Continue checking the
> revision rather than an immediate error return so the update result
> remains consistent with the revision changes.
>
> Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
> ---
> V1 -> V2: Do not raise panic, inline cpuid check and massage the changelog (Dave)


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


<rant>
What a long-winded way to check whether MCU_ENUM is present... I 
understand it's outside of the purview of software but couldn't this 
been put into some customs CPUID leaf ... sigh
</rant>