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Re: Introduction of stable interface between Xenstore and hypervisor

On 10/09/2021 14:46, Juergen Gross wrote:
On 10.09.21 15:22, Jan Beulich wrote:
On 09.09.2021 08:27, Juergen Gross wrote:
- Addition of a new stable hypercall ("get domain state") returning the
    following information:
    + domid of a domain having the bit set in above bitmap
    + state of that domain (existing, dying)
    + sequence count of that domain
    The related bit is reset in the bitmap as a side effect of the call.

What I'd like us to consider up front is whether xenstored is going
to remain only entity interested in this kind of information. The
entire design looks to leverage that there's only a single consumer
in the system.

Right. I'm just writing some RFC patches, and I have coded this
interface to be usable only for the domain having VIRQ_DOM_EXC

The alternative (IMO) would have been to expose the domain-state
bitmap to Xenstore (and/or other interested parties).

If we do that, let's do in such way that guest_*_bit() helpers are not necessary because they are a massive hammer on Arm. This means the bitmap would have to be read-only for the domain.


Julien Grall



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