RE: [PATCH v5 0/9] Enhance the hv_vmbus driver to support hibernation

From: Dexuan Cui <decui@microsoft.com>
To: Sasha Levin <sashal@kernel.org>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Sasha Levin <Alexander.Levin@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	KY Srinivasan <kys@microsoft.com>,
	Michael Kelley <mikelley@microsoft.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v5 0/9] Enhance the hv_vmbus driver to support hibernation
Date: Fri, 6 Sep 2019 22:45:31 +0000	[thread overview]
Message-ID: <PU1P153MB01697512A097B489E0440E13BFBA0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20190906200325.GD1528@sasha-vm>

> From: Sasha Levin <sashal@kernel.org>
> Sent: Friday, September 6, 2019 1:03 PM
> On Thu, Sep 05, 2019 at 11:01:14PM +0000, Dexuan Cui wrote:
> >This patchset (consisting of 9 patches) was part of the v4 patchset (consisting
> >of 12 patches):
> >
> >The other 3 patches in v4 are posted in another patchset, which will go
> >through the tip.git tree.
> >
> >All the 9 patches here are now rebased to the hyperv tree's hyperv-next
> branch, and all the 9 patches have Michael Kelley's Signed-off-by's.
> >
> >Please review.
> 
> Given that these two series depend on each other, I'd much prefer for
> them to go through one tree.

Hi Sasha,
Yeah, that would be ideal. The problem here is: the other patchset conflicts
with the existing patches in the tip.git tree's timers/core branch, so IMO 
the 3 patches have to go through the tip tree:

[PATCH v5 1/3] x86/hyper-v: Suspend/resume the hypercall page for hibernation
[PATCH v5 2/3] x86/hyper-v: Implement hv_is_hibernation_supported()
[PATCH v5 3/3] clocksource/drivers: Suspend/resume Hyper-V clocksource for hibernation

> But, I may be wrong, and I'm going to see if a scenario such as this
> make sense. I've queued this one to the hyperv-next, but I'll wait for
> the x86 folks to send their pull request to Linus first before I do it
> for these patches.

Actually IMHO you don't need to wait, because there is not a build
dependency, so either patchset can go into the Linus's tree first.

The 2 patchsets are just the first step to make hibernation work for Linux VM
running on Hyper-V. Next I'm going to post some high-level VSC patches for
hv_balloon, hv_utils, hv_netvsc, hid_hyperv, hv_storvsc, hyperv_keyboard, 
hyperv_fb,etc. All of these should go through the hyperv tree, since they're
pure hyper-v changes, and they depend on this 9-patch patchset. I'll make
a note in every patch so the subsystem maintainers will be aware and ack it.

Among the VSC patches, the hv_balloon patch does depend on the 2nd patch:
    [PATCH v5 2/3] x86/hyper-v: Implement hv_is_hibernation_supported().
I think I'll wait for the aforementioned 2 patchsets to be in first, before posting
the hv_balloon patch.

> Usually cases such as these are the exception, but for Hyper-V it seems
> to be the norm, so I'm curious to see how this will unfold.
> 
> Thanks,
> Sasha

Thanks for taking care all the patches!

Thanks,
-- Dexuan