Re: [PATCH v2 01/16] KVM: x86: Rename register accessors to be GPR-specific

["Chang S. Bae" <chang.seok.bae@intel.com>]

On 3/4/2026 5:35 PM, Sean Christopherson wrote:
> On Mon, Jan 12, 2026, Chang S. Bae wrote:
>> Refactor the VCPU register state accessors to make them explicitly
>> GPR-only.
> 
> I like "register" though.

Yeah, agree that it is more general.

> 
>> The existing register accessors operate on the cached VCPU register
>> state. That cache holds GPRs and RIP. RIP has its own interface already.
> 
> Isn't it possible that e.g. get_vmx_mem_address() will do kvm_register_read()
> for a RIP-relative address?  One could RIP isn't a pure GPR, but it's also not
> something entirely different either.

The 'reg' argument has historically matched the index of the register 
cache array, vcpu::arch::regs[]. When extending the accessors to support 
EGPRs, it looked smooth to keep using it as a register ID, since that 
wires up cleanly with VMX instruction info and emulator sites. But then 
reg=16 immediately conflicts with RIP.

Separating accessors for RIP and GPRs was an option. Yes, the usages are 
very close and EGPRs are strictly not *legacy* GPRs.

Then, another option would be adjust RIP numbering. For example, use 
something like VCPU_REGS_RIP=32 for the accessor, while keeping a 
separate value like __VCPU_REGS_RIP=16 for the reg cache index. But 
there are many sites directly referencing regs[] and the change looked 
rather ugly -- two numberings for RIP alone.

Thoughts?