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Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode
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From: |
Dr. David Alan Gilbert |
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Subject: |
Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode |
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Date: |
Tue, 25 Aug 2020 09:15:04 +0100 |
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User-agent: |
Mutt/1.14.6 (2020-07-11) |
* 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
- [PATCH v5 1/8] hw/i386: Remove node_id, nr_nodes and nodes_per_pkg from topology, (continued)
- [PATCH v5 1/8] hw/i386: Remove node_id, nr_nodes and nodes_per_pkg from topology, Babu Moger, 2020/08/21
- [PATCH v5 2/8] Revert "i386: Fix pkg_id offset for EPYC cpu models", Babu Moger, 2020/08/21
- [PATCH v5 3/8] Revert "target/i386: Enable new apic id encoding for EPYC based cpus models", Babu Moger, 2020/08/21
- [PATCH v5 7/8] Revert "hw/386: Add EPYC mode topology decoding functions", Babu Moger, 2020/08/21
- [PATCH v5 8/8] i386: Simplify CPUID_8000_001E for AMD, Babu Moger, 2020/08/21
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Dr. David Alan Gilbert, 2020/08/24
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Babu Moger, 2020/08/24
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode,
Dr. David Alan Gilbert <=
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/25
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Dr. David Alan Gilbert, 2020/08/25
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/26
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Dr. David Alan Gilbert, 2020/08/26
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/27
- RE: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Babu Moger, 2020/08/27
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/28
- RE: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Babu Moger, 2020/08/28
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Dr. David Alan Gilbert, 2020/08/28
- Re: [PATCH v5 0/8] Remove EPYC mode apicid decode and use generic decode, Igor Mammedov, 2020/08/28