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Message-ID: <20200911204447.GA23729@dev-dsk-anchalag-2a-9c2d1d96.us-west-2.amazon.com>
Date: Fri, 11 Sep 2020 20:44:47 +0000
From: Anchal Agarwal <anchalag@...zon.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>,
"the arch/x86 maintainers" <x86@...nel.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
Linux PM <linux-pm@...r.kernel.org>,
Linux Memory Management List <linux-mm@...ck.org>,
"Kamata, Munehisa" <kamatam@...zon.com>,
"Stefano Stabellini" <sstabellini@...nel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
<roger.pau@...rix.com>, Jens Axboe <axboe@...nel.dk>,
David Miller <davem@...emloft.net>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Peter Zijlstra <peterz@...radead.org>,
Eduardo Valentin <eduval@...zon.com>,
"Singh, Balbir" <sblbir@...zon.com>,
<xen-devel@...ts.xenproject.org>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
netdev <netdev@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
David Woodhouse <dwmw@...zon.co.uk>,
"Benjamin Herrenschmidt" <benh@...nel.crashing.org>
Subject: Re: [PATCH v3 00/11] Fix PM hibernation in Xen guests
On Fri, Aug 28, 2020 at 06:39:45PM +0000, Anchal Agarwal wrote:
> On Fri, Aug 28, 2020 at 08:29:24PM +0200, Rafael J. Wysocki wrote:
> > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe.
> >
> >
> >
> > On Fri, Aug 28, 2020 at 8:26 PM Anchal Agarwal <anchalag@...zon.com> wrote:
> > >
> > > On Fri, Aug 21, 2020 at 10:22:43PM +0000, Anchal Agarwal wrote:
> > > > Hello,
> > > > This series fixes PM hibernation for hvm guests running on xen hypervisor.
> > > > The running guest could now be hibernated and resumed successfully at a
> > > > later time. The fixes for PM hibernation are added to block and
> > > > network device drivers i.e xen-blkfront and xen-netfront. Any other driver
> > > > that needs to add S4 support if not already, can follow same method of
> > > > introducing freeze/thaw/restore callbacks.
> > > > The patches had been tested against upstream kernel and xen4.11. Large
> > > > scale testing is also done on Xen based Amazon EC2 instances. All this testing
> > > > involved running memory exhausting workload in the background.
> > > >
> > > > Doing guest hibernation does not involve any support from hypervisor and
> > > > this way guest has complete control over its state. Infrastructure
> > > > restrictions for saving up guest state can be overcome by guest initiated
> > > > hibernation.
> > > >
> > > > These patches were send out as RFC before and all the feedback had been
> > > > incorporated in the patches. The last v1 & v2 could be found here:
> > > >
> > > > [v1]: https://lkml.org/lkml/2020/5/19/1312
> > > > [v2]: https://lkml.org/lkml/2020/7/2/995
> > > > All comments and feedback from v2 had been incorporated in v3 series.
> > > >
> > > > Known issues:
> > > > 1.KASLR causes intermittent hibernation failures. VM fails to resumes and
> > > > has to be restarted. I will investigate this issue separately and shouldn't
> > > > be a blocker for this patch series.
> > > > 2. During hibernation, I observed sometimes that freezing of tasks fails due
> > > > to busy XFS workqueuei[xfs-cil/xfs-sync]. This is also intermittent may be 1
> > > > out of 200 runs and hibernation is aborted in this case. Re-trying hibernation
> > > > may work. Also, this is a known issue with hibernation and some
> > > > filesystems like XFS has been discussed by the community for years with not an
> > > > effectve resolution at this point.
> > > >
> > > > Testing How to:
> > > > ---------------
> > > > 1. Setup xen hypervisor on a physical machine[ I used Ubuntu 16.04 +upstream
> > > > xen-4.11]
> > > > 2. Bring up a HVM guest w/t kernel compiled with hibernation patches
> > > > [I used ubuntu18.04 netboot bionic images and also Amazon Linux on-prem images].
> > > > 3. Create a swap file size=RAM size
> > > > 4. Update grub parameters and reboot
> > > > 5. Trigger pm-hibernation from within the VM
> > > >
> > > > Example:
> > > > Set up a file-backed swap space. Swap file size>=Total memory on the system
> > > > sudo dd if=/dev/zero of=/swap bs=$(( 1024 * 1024 )) count=4096 # 4096MiB
> > > > sudo chmod 600 /swap
> > > > sudo mkswap /swap
> > > > sudo swapon /swap
> > > >
> > > > Update resume device/resume offset in grub if using swap file:
> > > > resume=/dev/xvda1 resume_offset=200704 no_console_suspend=1
> > > >
> > > > Execute:
> > > > --------
> > > > sudo pm-hibernate
> > > > OR
> > > > echo disk > /sys/power/state && echo reboot > /sys/power/disk
> > > >
> > > > Compute resume offset code:
> > > > "
> > > > #!/usr/bin/env python
> > > > import sys
> > > > import array
> > > > import fcntl
> > > >
> > > > #swap file
> > > > f = open(sys.argv[1], 'r')
> > > > buf = array.array('L', [0])
> > > >
> > > > #FIBMAP
> > > > ret = fcntl.ioctl(f.fileno(), 0x01, buf)
> > > > print buf[0]
> > > > "
> > > >
> > > > Aleksei Besogonov (1):
> > > > PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA
> > > >
> > > > Anchal Agarwal (4):
> > > > x86/xen: Introduce new function to map HYPERVISOR_shared_info on
> > > > Resume
> > > > x86/xen: save and restore steal clock during PM hibernation
> > > > xen: Introduce wrapper for save/restore sched clock offset
> > > > xen: Update sched clock offset to avoid system instability in
> > > > hibernation
> > > >
> > > > Munehisa Kamata (5):
> > > > xen/manage: keep track of the on-going suspend mode
> > > > xenbus: add freeze/thaw/restore callbacks support
> > > > x86/xen: add system core suspend and resume callbacks
> > > > xen-blkfront: add callbacks for PM suspend and hibernation
> > > > xen-netfront: add callbacks for PM suspend and hibernation
> > > >
> > > > Thomas Gleixner (1):
> > > > genirq: Shutdown irq chips in suspend/resume during hibernation
> > > >
> > > > arch/x86/xen/enlighten_hvm.c | 7 +++
> > > > arch/x86/xen/suspend.c | 63 ++++++++++++++++++++
> > > > arch/x86/xen/time.c | 15 ++++-
> > > > arch/x86/xen/xen-ops.h | 3 +
> > > > drivers/block/xen-blkfront.c | 122 ++++++++++++++++++++++++++++++++++++--
> > > > drivers/net/xen-netfront.c | 96 +++++++++++++++++++++++++++++-
> > > > drivers/xen/events/events_base.c | 1 +
> > > > drivers/xen/manage.c | 46 ++++++++++++++
> > > > drivers/xen/xenbus/xenbus_probe.c | 96 +++++++++++++++++++++++++-----
> > > > include/linux/irq.h | 2 +
> > > > include/xen/xen-ops.h | 3 +
> > > > include/xen/xenbus.h | 3 +
> > > > kernel/irq/chip.c | 2 +-
> > > > kernel/irq/internals.h | 1 +
> > > > kernel/irq/pm.c | 31 +++++++---
> > > > kernel/power/user.c | 7 ++-
> > > > 16 files changed, 464 insertions(+), 34 deletions(-)
> > > >
> > > > --
> > > > 2.16.6
> > > >
> > > A gentle ping on the series in case there is any more feedback or can we plan to
> > > merge this? I can then send the series with minor fixes pointed by tglx@
> >
> > Some more time, please!
> >
> Sure happy to answer any more questions and fix more BUGS!!
>
> --
> Anchal
>
A gentle ping on this one again!
--
Anchal
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