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

[David Woodhouse]

On Wed, 2018-01-24 at 07:09 -0800, Arjan van de Ven wrote:
> On 1/24/2018 1:10 AM, Greg Kroah-Hartman wrote:
> > 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

I really think that's fine. Anyone who uses beta microcodes, should be
perfectly prepared to deal with the results. And probably *wanted* to
be able to actually test them, instead of having the kernel refuse to
do so.

So if there are beta microcodes floating around with numbers higher
than in Intel's currently-published list, which are not yet known to be
safe (or even if they're known not to be), that's absolutely OK.

If you're telling me that there will be *publicly* released microcodes
with version numbers higher than those in the list, which still have
the same issues... well, then I think Mr Shouty is going to come for
another visit.

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