Re: [PATCH 0/3] x86/microcode: support for microcode update in Xen dom0

Jeremy Fitzhardinge
2011-10-12T15:39:13Z

On 10/12/2011 03:16 AM, Borislav Petkov wrote:
> On Tue, Oct 11, 2011 at 08:40:05PM -0400, Jeremy Fitzhardinge wrote:
>> Ping?
>>
>> On 09/26/2011 11:17 AM, Jeremy Fitzhardinge wrote:
>>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
>>>
>>> Hi all,
>>>
>>> I'm proposing this for the next merge window v3.2.
>>>
>>> I originally posted this early this year, and it prompted a debate
>>> about what the "proper" way that Linux should do microcode updates,
>>> with the general concensus being "earlier", ideally in the bootloader
>>> (or in the case of Xen, as the hypervisor boots before starting any
>>> domains). However, as far as I know there has been no progress along
>>> those lines.
> Err,
>
> wait a sec, last time the suggestion was that _because_ xen supports the
> multiboot protocol, implementing an early solution would be even easier
> for you:
>
> http://marc.info/?l=linux-kernel&m=129667641316947&w=2
>
> Why would a xen microcode solution would even be contingent on how
> upstream Linux solves it (and when)?
>
> AFAICT, you want to hand off the microcode image from the bootloader to
> the hypervisor and update ucode there - no need for dom0 changes...

I don't want a Xen-specific solution to this. If Linux overall moves to
a boot-time microcode loading scheme, then I'm happy to support it. But
in the meantime, I want a Xen system to Just Work in the same manner as
a non-Xen one, without requiring special support from all the distros.

J