Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Babu Moger (babu.moger@amd.com) wrote:
> Hi Dave,
> 
> On 8/24/20 1:41 PM, Dr. David Alan Gilbert wrote:
> > * Babu Moger (babu.moger@amd.com) wrote:
> >> To support some of the complex topology, we introduced EPYC mode apicid decode.
> >> But, EPYC mode decode is running into problems. Also it can become quite a
> >> maintenance problem in the future. So, it was decided to remove that code and
> >> use the generic decode which works for majority of the topology. Most of the
> >> SPECed configuration would work just fine. With some non-SPECed user inputs,
> >> it will create some sub-optimal configuration.
> >> Here is the discussion thread.
> >> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fqemu-devel%2Fc0bcc1a6-1d84-a6e7-e468-d5b437c1b254%40amd.com%2F&data=02%7C01%7Cbabu.moger%40amd.com%7C74d90724af9c4adcc75008d8485d4d16%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637338912853492167&sdata=GTsMKcpeYXAA0CvpLTirPHKdNSdlJE3RuPjCtSyWtGQ%3D&reserved=0
> >>
> >> This series removes all the EPYC mode specific apicid changes and use the generic
> >> apicid decode.
> > 
> > Hi Babu,
> >   This does simplify things a lot!
> > One worry, what happens about a live migration of a VM from an old qemu
> > that was using the node-id to a qemu with this new scheme?
> 
> The node_id which we introduced was only used internally. This wasn't
> exposed outside. I don't think live migration will be an issue.

Didn't it become part of the APIC ID visible to the guest?

Dave

-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK