Re: [kvm-unit-tests PATCH 1/3] x86: Add define for MSR_IA32_PRED_CMD's PRED_CMD_IBPB (bit 0)

[Sean Christopherson <seanjc@google.com>]

On Wed, Mar 29, 2023, Xiaoyao Li wrote:
> On 3/28/2023 11:07 PM, Sean Christopherson wrote:
> > On Tue, Mar 28, 2023, Xiaoyao Li wrote:
> > > On 3/28/2023 1:02 PM, Sean Christopherson wrote:
> > > > Add a define for PRED_CMD_IBPB and use it to replace the open coded '1' in
> > > > the nVMX library.
> > > 
> > > What does nVMX mean here?
> > 
> > Nested VMX.  From KUT's perspective, the testing exists to validate KVM's nested
> > VMX implementation.  If it's at all confusing, I'll drop the 'n'  And we've already
> > established that KUT can be used on bare metal, even if that's not the primary use
> > case.
> 
> So vmexit.flat is supposed to be ran in L1 VM?

Not all of the tests can be run on bare metal, e.g. I can't imagine the VMware
backdoor test works either.

> I'm confused and interested in how KUT is used on bare metal.

I haven't used KUT on bare metal myself, but the idea is pretty much the same as
running under QEMU/KVM: boot into the KUT "kernel" after getting through firmwrae
instead of transferring control to an actual OS.  I assume the biggest challenges
are getting the image loaded, and getting info out of KUT, e.g. having a serial
port with something on the backend to capture/display output.