RE: [PATCH v2 06/10] x86/mce: Convert multiple if () statements into a switch() statement

[Zhuo, Qiuxu]

> From: Hansen, Dave <dave.hansen@xxxxxxxxx>
> [...]
> On 10/21/24 09:06, Luck, Tony wrote:
> >>         /*
> >>          * All newer Intel systems support MCE broadcasting. Enable
> >>          * synchronization with a one second timeout.
> >>          */
> >> -       if ((c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xe)) &&
> >> -           cfg->monarch_timeout < 0)
> >> +       if (c->x86_vfm >= INTEL_CORE_YONAH && cfg->monarch_timeout <
> >> + 0)
> >>                 cfg->monarch_timeout = USEC_PER_SEC;
> > This change is correct. But the old code makes it more explicit that
> > CPUs in families > 6 take this action. As the author of the VFM
> > changes it's clear to me, maybe less so to others?
> >
> > But maybe its OK.  The comment does help a lot. Anyone else have thoughts
> on this?
> 
> It certainly is a bit subtle.
> 
> To me, the earlier check would be even better if it were:
> 
> -	if (c->x86 < 6)

Thanks, Dave. 
OK, I'll update it in the next version. 
Apart from this, I'll also add a comment below, as suggested by Sohil, to make it explicit that it's for prior to family 6.

   /* Older CPUs (prior to family 6) don't need quirks */
> +	if (c->x86_vfm < INTEL_PENTIUM_PRO)
> 		return;
> 
> That at least makes it more clear that it's a range of models and avoids having
> a ->x86 check mixed with a ->x86_vfm one.