Re: [PATCH v7 7/7] Documentation: KVM: Add hypercall for LoongArch

[maobibo]

On 2024/3/24 上午2:40, WANG Xuerui wrote:
> On 3/15/24 16:11, Bibo Mao wrote:
> > [snip]
> > +KVM hypercall ABI
> > +=================
> > +
> > +Hypercall ABI on KVM is simple, only one scratch register a0 and at most
> > +five generic registers used as input parameter. FP register and 
> > vector register
> > +is not used for input register and should not be modified during 
> > hypercall.
> > +Hypercall function can be inlined since there is only one scratch 
> > register.
>
> Maybe it's better to describe the list of preserved registers with an 
> expression such as "all non-GPR registers shall remain unmodified after 
> returning from the hypercall", to guard ourselves against future ISA 
> state additions.
Sorry, I do not understand. What is the meaning of "all non-GPR 
registers"?  Can you give an example?

Regards
Bibo Mao
> But I still maintain that it's better to promise less here, and only 
> hint on the extensive preservation of context as an implementation 
> detail. It is for not losing our ability to save/restore less in the 
> future, should we decide to do so.