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 5/7] Drivers: hv: vmbus: Ignore the offers when resuming from hibernation
Date: Wed, 31 Jul 2019 00:01:53 +0000 [thread overview]
Message-ID: <PU1P153MB01699A21E81D9E8E872A190ABFDF0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <MWHPR21MB078481A7C7F65E0297135D41D7DC0@MWHPR21MB0784.namprd21.prod.outlook.com>
> From: Michael Kelley <mikelley@microsoft.com>
> Sent: Tuesday, July 30, 2019 4:07 PM
> > +
> > + if (oldchannel != NULL) {
> > + atomic_dec(&vmbus_connection.offer_in_progress);
> > +
> > + /*
> > + * We're resuming from hibernation: we expect the host to send
> > + * exactly the same offers that we had before the hibernation.
> > + */
> > + offer_sz = sizeof(*offer);
> > + if (memcmp(offer, &oldchannel->offermsg, offer_sz) == 0)
> > + return;
>
> The offermsg contains "reserved" and "padding" fields. Does Hyper-V
> guarantee that all these fields are the same in the new offer after resuming
> from hibernation?
Yes. I confirmed this with Hyper-V team. The reserved/padding fields don't change
across hiberantion. BTW, the fields are filled with zeros since they're not used.
> Or should a less stringent check be made? For example,
> I could imagine a newer version of Hyper-V allowing a VM that was
> hibernated on an older version to be resumed. But one of the reserved fields
> might be used in the newer version, and the comparison could fail
> unnecessarily.
Upon resume, Linux VM always uses the same version, which was used when the
VM firstly booted up before suspend, to re-negotiate with the host.
> > +
> > + pr_err("Mismatched offer from the host (relid=%d)!\n",
> > + offer->child_relid);
> > +
> > + print_hex_dump_debug("Old vmbus offer: ", DUMP_PREFIX_OFFSET,
> 4,
> > + 4, &oldchannel->offermsg, offer_sz, false);
> > + print_hex_dump_debug("New vmbus offer: ",
> DUMP_PREFIX_OFFSET, 4,
> > + 4, offer, offer_sz, false);
>
> The third argument to print_hex_dump() is the rowsize and is specified as must
> be 16 or 32.
Thanks! I misunderstood the argument. I'll change it to 16.
Thanks,
-- Dexuan
next prev parent reply other threads:[~2019-07-31 0:02 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 5:29 [PATCH 0/7] Enhance the hv_vmbus driver to support hibernation Dexuan Cui
2019-07-09 5:29 ` [PATCH 1/7] x86/hyper-v: Suspend/resume the hypercall page for hibernation Dexuan Cui
2019-07-30 22:18 ` Michael Kelley
2019-07-09 5:29 ` [PATCH 2/7] clocksource/drivers: Suspend/resume Hyper-V clocksource " Dexuan Cui
2019-07-30 22:23 ` Michael Kelley
2019-07-09 5:29 ` [PATCH 3/7] Drivers: hv: vmbus: Split hv_synic_init/cleanup into regs and timer settings Dexuan Cui
2019-07-30 22:35 ` Michael Kelley
2019-07-30 23:18 ` Dexuan Cui
2019-07-09 5:29 ` [PATCH 4/7] Drivers: hv: vmbus: Suspend/resume the synic for hibernation Dexuan Cui
2019-07-09 5:29 ` [PATCH 5/7] Drivers: hv: vmbus: Ignore the offers when resuming from hibernation Dexuan Cui
2019-07-30 23:07 ` Michael Kelley
2019-07-31 0:01 ` Dexuan Cui [this message]
2019-07-09 5:29 ` [PATCH 6/7] Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation Dexuan Cui
2019-07-30 23:25 ` Michael Kelley
2019-07-31 0:16 ` Dexuan Cui
2019-07-09 5:29 ` [PATCH 7/7] Drivers: hv: vmbus: Implement suspend/resume for VSC drivers " Dexuan Cui
2019-07-30 23:38 ` Michael Kelley
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