On Mon, Dec 18, 2017 at 08:20:18PM +1100, David Gibson wrote: > This series is a first draft to add the notion of optional > capabilities to the "pseries" machine type. A default set of > capabilities is selected based on the machine type version and > selected cpu model, but this can be overridden with machine > parameters. > > The purpose of this is to get rid of a number of places where we > implicitly decide what features to advertise to the guest based on > capabilities of the host. This is bad, because it means it's > difficult to be certain if machines started at different ends of a > migration really match from the guest's point of view. > > By giving the user explicit control of these optional features, then > validating that the chosen ones can be supplied on the host we make > behaviour more predictable. > > The more specific motivation for this is that POWER9 has bugs in its > hardware transactional memory (HTM) implementation making it unsafe to > migrate POWER8 guests to POWER9 if they use HTM.
I've fixed the user-after-free bug Greg pointed out and merged this into ppc-for-2.12. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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