[PATCH 2/3] rfi-flush: Make it possible to call setup_rfi_flush() again

[Mauricio Faria de Oliveira]

Hi Michael, Michal,

I got back from vacation. Checking this one.

On 02/20/2018 02:06 PM, Michal Suchánek wrote:
>> I did it the way I did because otherwise we waste memory on every
>> system on earth just to support a use case that we don't actually
>> intend for anyone to ever use - ie. migrating from a patched machine
>> to an unpatched machine.

If this thread eventually closes in 'ok, so that memory has to be
reserved/wasted anyway', that can be done only in pseries, right?

It seems not so much memory for this particular platform/hardware.

> If you have multiple hosts running some LPMs and want to update them
> without shutting down the whole thing I suppose it might easily happen
> that a machine (re)started on a patched host is migrated to unpatched
> host.

Right, but that should be temporary, I think -- after updating some of
the hosts, the LPAR(s) can be migrated back to one of them, where the
fallback flush is not required anymore.

>> I think I'm inclined to leave it the way it is, unless you feel
>> strongly about it Michal?

> I think it would be more user friendly to either support the fallback
> method 100% or remove it and require patched firmware.

I beg to disagree.  Since the matter is a security issue, the option
of still have some sort of fix that works on unpatched firmware does
look good and friendly to users (rather than require 'you _must_ get
the firmware update') IMHO.

cheers,
Mauricio