Re: [RFC PATCH 1/4] KVM: selftests: Add support for creating non-default type VMs

From: Sean Christopherson
Date: Wed Aug 04 2021 - 19:31:28 EST

On Wed, Aug 04, 2021, Erdem Aktas wrote:
> Thank you all for all that great feedback! I will include them in my v2.
> On Wed, Aug 4, 2021 at 7:46 AM Maxim Levitsky <mlevitsk@xxxxxxxxxx> wrote:
> >
> > > > > Can we pass KVM_X86_LEGACY_VM (whatever name when it's upstreamed)
> > > > > instead of 0?
> > > >
> I was originally thinking of doing this but Sean has suggested that we
> should use 0 to make it arch-agnostic for creating default VMs.
> +Sean Christopherson : What do you think?

I hate passing '0', but KVM_X86_LEGACY_VM is worse because it's nonsensical for
other architectures.

> >
> > KVM_X86_NORMAL_VM is a very good name IMHO as well.

But that implies protected guests are abnormal! And KVM_X86_STANDARD_VM would
imply protected guests are sub-standard! I'm only half-joking, e.g. if we get
to the point where the majority of guests being run are protected guests, then
!protected guests are no longer the "standard".

Looking at other architectures, I think the least awful option is a generic
KVM_VM_TYPE_AUTO, or maybe KVM_VM_TYPE_DEFAULT. That aligns with how '0' is used
by PPC, MIPS, and arm64[*], and would work for x86 as well without implying what's

[*] arm64 uses the type to specify the IPA width (I'm not even sure what that is),
but thankfully interprets '0' as a default.