Re: [V2 PATCH 4/8] KVM: selftests: x86: Precompute the result for is_{intel,amd}_cpu()

From: David Matlack
Date: Wed Sep 21 2022 - 17:39:30 EST


On Thu, Sep 15, 2022 at 12:04:44AM +0000, Vishal Annapurve wrote:
> Cache the vendor CPU type in a global variable so that multiple calls
> to is_intel_cpu() do not need to re-execute CPUID.
>
> Add cpu vendor check in kvm_hypercall() so that it executes correct
> vmcall/vmmcall instruction when running on Intel/AMD hosts. This avoids
> exit to KVM which anyway tries to patch the instruction according to
> the cpu type.

Out of curiousity, why do we want to avoid this exit?