Re: [RFC PATCH 06/16] x86/xen: add shared_info support to xenhost_t

From: Ankur Arora
Date: Sat Jun 08 2019 - 01:06:33 EST

On 2019-06-07 8:08 a.m., Juergen Gross wrote:
On 09.05.19 19:25, Ankur Arora wrote:
HYPERVISOR_shared_info is used for irq/evtchn communication between the
guest and the host. Abstract out the setup/reset in xenhost_t such that
nested configurations can use both xenhosts simultaneously.

I have mixed feelings about this patch. Most of the shared_info stuff we
don't need for the nested case. In the end only the event channels might
be interesting, but we obviously want them not for all vcpus of the L1
hypervisor, but for those of the current guest.
Agreed about the mixed feelings part. shared_info does feel far too
heavy to drag along just for the event-channel state.
Infact, on thinking a bit more, a better abstraction for nested
event-channels would have been as an extension to the primary
xenhost's event-channel bits.
(The nested upcalls also go via the primary xenhost in patch-8.)


So I think just drop that patch for now. We can dig it out later in case > nesting wants it again.