Re: [Xen-devel] pvops microcode support for AMD FAM >= 15

[Ian Campbell <ijc@xxxxxxxxxxxxxx>]

On Mon, 2012-11-26 at 13:44 +0000, Jan Beulich wrote:
> >>> On 26.11.12 at 14:21, Ian Campbell <ijc@xxxxxxxxxxxxxx> wrote:
> > Debian has decided to take Jeremy's microcode patch [0] as an interim
> > measure for their next release. (TL;DR -- Debian is shipping pvops Linux
> > 3.2 and Xen 4.1 in the next release. See http://bugs.debian.org/693053 
> > and https://lists.debian.org/debian-devel/2012/11/msg00141.html for some
> > more background).
> > 
> > However the patch is a bit old and predates the use introduction of
> > separate firmware files for AMD family >= 15h. Looking at the SuSE
> > forward ported classic Xen patches it seems like the following patch is
> > all that is required. But it seems a little too simple to be true and I
> > don't have any such processors to test on.
> > 
> > Jan, can you recall if it really is that easy on the kernel side ;-)
> 
> While so far I didn't myself run anything on post-Fam10 systems
> either, it really ought to be that easy - the patch format didn't
> change, it's just that they decided to spit the files by family to
> keep them manageable.
> 
> The only other thing to check for is that you don't have any
> artificial size restriction left in that code (I think patch files early
> on were limited to 4k in size, and that got lifted during the last
> couple of years).

I managed to find a machine and try this and it turns out that all that
was missing from the kernel side was:

        @@ -58,7 +58,7 @@
         
         static enum ucode_state xen_request_microcode_fw(int cpu, struct 
device *device)
         {
        -       char name[30];
        +       char name[36];
                struct cpuinfo_x86 *c = &cpu_data(cpu);
                const struct firmware *firmware;
                struct ucode_cpu_info *uci = ucode_cpu_info + cpu;

> The hypervisor is really going to take care of all other aspects
> here.

There may be some  other issue here (I replied to Boris about it) but it
does seem like the kernel side is now correct.

Ian.


-- 
Ian Campbell

Friction is a drag.


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