Comment 1 for bug 1832622

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Christian Ehrhardt  (paelzer) wrote :

I'm glad that the kernel patch is already integrated by bug 1822870 in >=Bionic - no dependency on the kernel here then.

The patches themselve look small and clean.
Thanks for identifying the extra dependencies to:
- 8fea7044 (>=3.0) target/ppc: Factor out the parsing in kvmppc_get_cpu_characteristics()
- 8c5909c4 (>=2.12) ppc/spapr-caps: Change migration macro to take full spapr-cap name

That overall makes the request to apply:
- 8c5909c4 (>=2.12) ppc/spapr-caps: Change migration macro to take full spapr-cap name
- 8fea7044 (>=3.0) target/ppc: Factor out the parsing in kvmppc_get_cpu_characteristics()
- 399b2896 (>=4.0) target/ppc/spapr: Add workaround option to SPAPR_CAP_IBS
- 8ff43ee4 (>=4.0) target/ppc/spapr: Add SPAPR_CAP_CCF_ASSIST

By reading the bug top down I ran into issues with patch #4, but then I read the rest and found that you already handled that. Taking the backport from the referenced git worked great, thanks Michael.

There was some minor noise bringing that to 2.12 and 3.0 but it worked rather straight forward as expected for 2.12. In qemu 3.0 thou we need something else for the fourth patch. Neither the upstream original (9 rejects), nor the backport you provided for 2.11 apply (10 rejects).
Upstream is a bit closer, the lack of "large decr" in qemu 3.0 shows up as context change a few times, but those were resovable.

For "SPAPR_CAP_CCF_ASSIST" I followed your backport of leaving no holes in the cap numbering (the alternative would be to retain it being 0x9, but leave some in between undefined which would break when iterating).

TODO
check cosmic applied include/hw/ppc/spapr.h SPAPR_CAP_CCF_ASSIST for wholes

IIRC Xenial has no P9 support and probably would be much harder to backport, so unless further discussion this is a Won't Fix for Xenial.

Timing: we have a qemu SRU in the pipe that needs verification and release. Once done we will enqueue that one.

But until then we can still work on this.
I opend MPs for internal review with the backports for Bionic/Cosmic/Disco/Eoan (linked to the bug here) and a PPA [1].
If you want to test anything ahead of proposed please feel free to take a look at MPs and/or the PPA.

[1]: https://launchpad.net/~paelzer/+archive/ubuntu/bug-1832622-qemu-spectre-ppc