From: Dexuan Cui <decui@microsoft.com>
To: Michael Kelley <mikelley@microsoft.com>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
Sasha Levin <Alexander.Levin@microsoft.com>,
"sashal@kernel.org" <sashal@kernel.org>,
Haiyang Zhang <haiyangz@microsoft.com>,
KY Srinivasan <kys@microsoft.com>,
"tglx@linutronix.de" <tglx@linutronix.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v3 12/12] Drivers: hv: vmbus: Resume after fixing up old primary channels
Date: Sat, 31 Aug 2019 04:37:14 +0000 [thread overview]
Message-ID: <PU1P153MB0169E3DD602FB575C346186DBFBC0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <DM5PR21MB01370691E881D59773B9EF60D7A40@DM5PR21MB0137.namprd21.prod.outlook.com>
> From: Michael Kelley <mikelley@microsoft.com>
> Sent: Friday, August 23, 2019 1:25 PM
>
> From: Dexuan Cui Sent: Monday, August 19, 2019 6:52 PM
> > @@ -890,6 +937,11 @@ static void vmbus_onoffer(struct
> > vmbus_channel_message_header *hdr)
> > false);
> > print_hex_dump_debug("New vmbus offer: ",
> DUMP_PREFIX_OFFSET,
> > 16, 4, offer, offer_sz, false);
> > +
> > + vmbus_setup_channel_state(oldchannel, offer);
> > +
> > + check_ready_for_resume_event();
>
> This is the error case where the new offer didn't match some aspect of
> the old offer.
Actually, this is not an error: besides the RELID, the host can also change
the offer->connection_id when it re-offers a device to the guest: so far,
I only see this host behavior for the VF vmbus device, and in this case, the
first vmbus_setup_channel_state() in vmbus_onoffer() is used to do the
fix-up:
channel->sig_event = offer->connection_id;
and later channel->sig_event is used in vmbus_set_event().
Despite the host behavior, it looks the VF vmbus device still works fine,
so (IMO) this is not an error. I'll write a separate email to report this to
Hyper-V team.
> Is the intent to proceed and use the new offer?
Yes, since this is not an error.
I'll add a comment before the "Mismatched offer from the host" for this.
BTW, the 3 debug lines here output nothing, unless we enable the output
by
cd /sys/kernel/debug/dynamic_debug/
echo 'file drivers/hv/channel_mgmt.c +p' > control
.
> I can see that check_ready_for_resume_event() has to be called in
> the error case, otherwise the resume operation will hang forever, but
> I'm not sure about setting up the channel state and then proceeding as
> if all is good.
> > +
> > return;
Thanks,
-- Dexuan
next prev parent reply other threads:[~2019-08-31 4:37 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 1:51 [PATCH v3 00/12] Enhance the hv_vmbus driver to support hibernation Dexuan Cui
2019-08-20 1:51 ` [PATCH v3 01/12] x86/hyper-v: Suspend/resume the hypercall page for hibernation Dexuan Cui
2019-08-20 1:51 ` [PATCH v3 02/12] x86/hyper-v: Implement hv_is_hibernation_supported() Dexuan Cui
2019-08-23 19:50 ` Michael Kelley
2019-08-30 23:37 ` Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 03/12] clocksource/drivers: Suspend/resume Hyper-V clocksource for hibernation Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 04/12] Drivers: hv: vmbus: Break out synic enable and disable operations Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 05/12] Drivers: hv: vmbus: Suspend/resume the synic for hibernation Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 06/12] Drivers: hv: vmbus: Add a helper function is_sub_channel() Dexuan Cui
2019-08-23 19:51 ` Michael Kelley
2019-08-20 1:52 ` [PATCH v3 07/12] Drivers: hv: vmbus: Implement suspend/resume for VSC drivers for hibernation Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 08/12] Drivers: hv: vmbus: Ignore the offers when resuming from hibernation Dexuan Cui
2019-08-23 19:56 ` Michael Kelley
2019-08-31 0:23 ` Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 09/12] Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 10/12] Drivers: hv: vmbus: Clean up hv_sock channels by force upon suspend Dexuan Cui
2019-08-23 20:02 ` Michael Kelley
2019-08-31 2:00 ` Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 11/12] Drivers: hv: vmbus: Suspend after cleaning up hv_sock and sub channels Dexuan Cui
2019-08-23 20:16 ` Michael Kelley
2019-08-31 2:54 ` Dexuan Cui
2019-08-20 1:52 ` [PATCH v3 12/12] Drivers: hv: vmbus: Resume after fixing up old primary channels Dexuan Cui
2019-08-23 20:25 ` Michael Kelley
2019-08-31 4:37 ` Dexuan Cui [this message]
2019-08-31 5:08 ` Dexuan Cui
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