On 09.05.19 19:25, Ankur Arora wrote:Yeah, a more narrowly tailored interface, where perhaps the L1-Xen
Abstract out xen_vcpu_id probing via (*probe_vcpu_id)(). Once that is
availab,e the vcpu_info registration happens via the VCPUOP hypercall.
Note that for the nested case, there are two vcpu_ids, and two vcpu_info
areas, one each for the default xenhost and the remote xenhost.
The vcpu_info is used via pv_irq_ops, and evtchn signaling.
The other VCPUOP hypercalls are used for management (and scheduling)
which is expected to be done purely in the default hypervisor.
However, scheduling of L1-guest does imply L0-Xen-vcpu_info switching,
which might mean that the remote hypervisor needs some visibility
into related events/hypercalls in the default hypervisor.
Another candidate for dropping due to layering violation, I guess.