Re: [PATCH v4 09/18] KVM: arm64: selftests: Add guest support to get the vcpuid

[Andrew Jones]

On Thu, Sep 09, 2021 at 10:10:56AM -0700, Raghavendra Rao Ananta wrote:
> On Thu, Sep 9, 2021 at 12:56 AM Andrew Jones <drjones@xxxxxxxxxx> wrote:
> >
> > On Thu, Sep 09, 2021 at 01:38:09AM +0000, Raghavendra Rao Ananta wrote:
...
> > > +     for (i = 0; i < KVM_MAX_VCPUS; i++) {
> > > +             vcpuid = vcpuid_map[i].vcpuid;
> > > +             GUEST_ASSERT_1(vcpuid != VM_VCPUID_MAP_INVAL, mpidr);
> >
> > We don't want this assert if it's possible to have sparse maps, which
> > it probably isn't ever going to be, but...
> >
> If you look at the way the array is arranged, the element with
> VM_VCPUID_MAP_INVAL acts as a sentinel for us and all the proper
> elements would lie before this. So, I don't think we'd have a sparse
> array here.

If we switch to my suggestion of adding map entries at vcpu-add time and
removing them at vcpu-rm time, then the array may become sparse depending
on the order of removals.

Thanks,
drew