Re: [RFC 05/10] x86/speculation: Add basic IBRS support infrastructure

[Arjan van de Ven]

On 1/24/2018 1:10 AM, Greg Kroah-Hartman wrote:
> > That means the whitelist ends up basically empty right now. Should I
> > add a command line parameter to override it? Otherwise we end up having
> > to rebuild the kernel every time there's a microcode release which
> > covers a new CPU SKU (which is why I kind of hate the whitelist, but
> > Arjan is very insistent...)
>
> Ick, no, whitelists are a pain for everyone involved.  Don't do that
> unless it is absolutely the only way it will ever work.
>
> Arjan, why do you think this can only be done as a whitelist?

I suggested a minimum version list for those cpus that need it.

microcode versions are tricky (and we've released betas etc etc with their own numbers)
and as a result there might be several numbers that have those issues with their IBRS for the same F/M/S