Re: [PATCH v2 5/8] KVM: x86: Reduce the number of emulator GPRs to '8' for 32-bit KVM

Kees Cook
2022-05-31T18:04:23Z

On Thu, May 26, 2022 at 09:08:14PM +0000, Sean Christopherson wrote:
> Reduce the number of GPRs emulated by 32-bit KVM from 16 to 8. KVM does
> not support emulating 64-bit mode on 32-bit host kernels, and so should
> never generate accesses to R8-15.
>
> Opportunistically use NR_EMULATOR_GPRS in rsm_load_state_{32,64}() now
> that it is precise and accurate for both flavors.
>
> Wrap the definition with full #ifdef ugliness; sadly, IS_ENABLED()
> doesn't guarantee a compile-time constant as far as BUILD_BUG_ON() is
> concerned.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

--
Kees Cook