On Mon, Apr 22, 2024 at 3:09 PM Jan Beulich <jbeul...@suse.com> wrote:
>
> On 16.04.2024 11:15, Fouad Hilly wrote:
> > Update microcode version check at Intel and AMD Level by:
> > Preventing the low level code from sending errors if the microcode
> > version provided is not a newer version.
>
> And why is this change (a) wanted and (b) correct?
I will improve the message description to cover more details and reasoning.
>
> > Other errors will be sent like before.
> > When the provided microcode version is the same as the current one, code
> > to point to microcode provided.
>
> I'm afraid I can't interpret this sentence.
"provided" is the firmware presented\provided to the code for firmware
flashing. As above, I will provide more comprehensive description.
>
> > Microcode version check happens at higher and common level in core.c.
> > Keep all the required code at low level that checks for signature and CPU
> > compatibility
> >
> > [v2]
> > Update message description to better describe the changes
>
> This belongs ...
>
> > Signed-off-by: Fouad Hilly <fouad.hi...@cloud.com>
> > ---
>
> ... below the separator.
>
> > --- a/xen/arch/x86/cpu/microcode/amd.c
> > +++ b/xen/arch/x86/cpu/microcode/amd.c
> > @@ -383,12 +383,8 @@ static struct microcode_patch *cf_check
> > cpu_request_microcode(
> > goto skip;
> > }
> >
> > - /*
> > - * If the new ucode covers current CPU, compare ucodes and
> > store the
> > - * one with higher revision.
> > - */
> > - if ( (microcode_fits(mc->patch) != MIS_UCODE) &&
> > - (!saved || (compare_header(mc->patch, saved) ==
> > NEW_UCODE)) )
> > + /* If the provided ucode covers current CPU, then store its
> > revision. */
> > + if ( (microcode_fits(mc->patch) != MIS_UCODE) && !saved )
> > {
> > saved = mc->patch;
> > saved_size = mc->len;
> > --- a/xen/arch/x86/cpu/microcode/intel.c
> > +++ b/xen/arch/x86/cpu/microcode/intel.c
> > @@ -294,8 +294,7 @@ static int cf_check apply_microcode(const struct
> > microcode_patch *patch)
> >
> > result = microcode_update_match(patch);
> >
> > - if ( result != NEW_UCODE &&
> > - !(opt_ucode_allow_same && result == SAME_UCODE) )
> > + if ( result != NEW_UCODE && result != SAME_UCODE )
> > return -EINVAL;
>
> Unlike the other two adjustments this one results in still permitting
> only same-or-newer. How does this fit with the AMD change above and
> the other Intel change ...
To be fixed in V3
>
> > @@ -354,12 +353,8 @@ static struct microcode_patch *cf_check
> > cpu_request_microcode(
> > if ( error )
> > break;
> >
> > - /*
> > - * If the new update covers current CPU, compare updates and store
> > the
> > - * one with higher revision.
> > - */
> > - if ( (microcode_update_match(mc) != MIS_UCODE) &&
> > - (!saved || compare_revisions(saved->rev, mc->rev) ==
> > NEW_UCODE) )
> > + /* If the provided ucode covers current CPU, then store its
> > revision. */
> > + if ( (microcode_update_match(mc) != MIS_UCODE) && !saved )
> > saved = mc;
>
> ... here?
I assume this refers to the previous comment? Which will be fixed in V3
>
> Jan
Thanks,
Fouad
