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

Sean Christopherson
2026-04-14T15:38:06Z

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[].