RE: [PATCH 6/7] Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation

Dexuan Cui
2019-07-31T00:16:27Z

> From: Michael Kelley <mikelley@microsoft.com>
> Sent: Tuesday, July 30, 2019 4:26 PM
> From: Dexuan Cui <decui@microsoft.com> Sent: Monday, July 8, 2019 10:30
> PM
> >
> > This is needed when we resume the old kernel from the "current" kernel.
>
> Perhaps a bit more descriptive commit message could be supplied?

I'll use this as the new changelog:

Before Linux enters hibernation, it sends the CHANNELMSG_UNLOAD message to
the host so all the offers are gone. After hibernation, Linux needs to re-negotiate
with the host using the same vmbus protocol version (which was in use
before hibernation), and ask the host to re-offer the vmbus devices.

> > +
> > + ret = vmbus_negotiate_version(msginfo, vmbus_proto_version);
>
> I think this code answers my earlier question: Upon resume, we negotiate
> the same
> VMbus protocol version we had at time of hibernation, even if running on a
> newer
> version of Hyper-V that might support newer protocol versions. Hence the
> offer
> messages should not have any previously reserved fields now being used. A
> comment to this effect would be useful.

Ok, let me add a comment before the line.

I'll post a v2 of the patchset, including the "[PATCH 4/7]", which needs a small change.

Thanks,
-- Dexuan