Re: [PATCH v10 00/30] Add KVM LoongArch support

[WANG Xuerui]

On 2023/5/18 10:56, maobibo wrote:
> Hi Paolo & Huacai,
>
> Sorry to bother you, I do not know flow of kernel code reviewing and merging.
>
> I want to know who should give a reviewed-by comments for these piece of code
> about loongarch kvm patch. It should be kvm maintainer or LoongArch maintianer?
> And any suggestion is welcome.

IMO the series should get its R-b from kvm maintainers (because it's kvm 
after all), and ideally also Acked-by from arch/loongarch maintainers 
(because it contains arch-specific code), according to common sense.

But in order for the various maintainers/reviewers to effectively 
review, maybe the LoongArch ISA manual Volume 3 (containing details 
about the virtualization extension) should be put out soon. AFAIK Huacai 
has access to it, by being a Loongson employee, but I don't know if he 
can review this series in the public without violating NDAs; Loongson 
outsiders like me and the kvm reviewers can only trust the commit 
messages and comments for the time being.

(BTW, how do people usually deal with pre-release hardware wit 
documentation not out yet? I suppose similar situations like this should 
turn up fairly often.)

Aside from this, there's another point: use of undocumented instructions 
in raw form with ".word". This currently doesn't work in LLVM/Clang, 
thus will slightly set back the ongoing ClangBuiltLinux enablement 
effort (currently all such usages in arch/loongarch are related to 
"invtlb" which has perfect support, and can be removed). AFAIK, such 
practice dates back to the LoongISA times, when the Loongson extended 
opcodes weren't supported by the upstream MIPS toolchains for some 
reason; but LoongArch is independent and not bounded by anyone else now, 
so it's better in terms of maintainability to just add the instructions 
to the toolchains. People will not be inconvenienced by having to use 
bleeding-edge LoongArch toolchains because upstream LoongArch devs have 
always been doing this.

--
WANG "xen0n" Xuerui

Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/