Re: [PATCH v2 1/6] KVM: x86: Add dedicated storage for guest RIP

[Xiaoyao Li]

On 4/14/2026 11:37 PM, Sean Christopherson wrote:
> On Tue, Apr 14, 2026, Chang S. Bae wrote:
> > On 4/14/2026 5:31 AM, Xiaoyao Li wrote:
> > > Even leave RIP in regs[], what is the problem by just allocating the
> > > index 16-31 to R16-R31 and making RIP the index 32?
> >
> > But why?
> >
> > Even though the array isn't explicitly labeled as GPRs, that's effectively
> > how it's being used, and RIP isn't part of that set.
> >
> > I don't think there is any benefit of leaving it in regs[].
>
> +1.  Chang's earlier argument that RIP isn't a proper GPR swayed me over, e.g. RIP
> doesn't have an architectural index.
>
> Keeping RIP in regs[] saves one line of code in arch/x86/include/asm/kvm_host.h,
> at the cost of making the code less readable (IMO) and incorrectly suggesting that
> RIP can be accessed like other regs[].

I'm not trying to object this patch. Instead, I'm trying to understand 
the justification of the change.

So I would expected an updated changelog with above justifications 
incorporated.