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* [Xen-devel] [RFC RESEND PATCH v3 00/12] Enable PM hibernation on guest VMs
@ 2020-02-14 23:21 Anchal Agarwal
  2020-02-14 23:22 ` [Xen-devel] [RFC PATCH v3 01/12] xen/manage: keep track of the on-going suspend mode Anchal Agarwal
                   ` (11 more replies)
  0 siblings, 12 replies; 37+ messages in thread
From: Anchal Agarwal @ 2020-02-14 23:21 UTC (permalink / raw)
  To: tglx, mingo, bp, hpa, x86, boris.ostrovsky, jgross, linux-pm,
	linux-mm, kamatam, sstabellini, konrad.wilk, roger.pau, axboe,
	davem, rjw, len.brown, pavel, peterz, eduval, sblbir, anchalag,
	xen-devel, vkuznets, netdev, linux-kernel, dwmw, fllinden, benh

Resending this in a more threaded format.
  
Hello,
I am sending out a v3 version of series of patches that implements guest
PM hibernation.
These guests are running on xen hypervisor. The patches had been tested
against mainstream kernel. EC2 instance hibernation feature is provided
to the AWS EC2 customers. PM hibernation uses swap space carved out within
the guest[or can be a separate partition], where hibernation image is
stored and restored from.

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.

This series includes some improvements over RFC series sent last year:
https://lists.xenproject.org/archives/html/xen-devel/2018-06/msg00823.html

Changelog v3:
1. Feedback from V2
2. Introduced 2 new patches for xen sched clock offset fix
3. Fixed pirq shutdown/restore in generic irq subsystem
4. Split save/restore steal clock patches into 2 for better readability

Changelog v2:
1. Removed timeout/request present on the ring in xen-blkfront during blkfront freeze
2. Fixed restoring of PIRQs which was apparently working for 4.9 kernels but not for
newer kernel. [Legacy irqs were no longer restored after hibernation introduced with
this commit "020db9d3c1dc0"]
3. Merged couple of related patches to make the code more coherent and readable
4. Code refactoring
5. Sched clock fix when hibernating guest is under heavy CPU load
Note: Under very rare circumstances we see resume failures with KASLR enabled only
on xen instances.  We are roughly seeing 3% failures [>1000 runs] when testing with
various instance sizes and some workload running on each instance. I am currently
investigating the issue as to confirm if its a xen issue or kernel issue.
However, it should not hold back anyone from reviewing/accepting these patches.

Testing done:
All testing is done for multiple hibernation cycle for 5.4 kernel on EC2.

Testing How to:
---------------
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

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
  genirq: Shutdown irq chips in suspend/resume during hibernation
  xen: Introduce wrapper for save/restore sched clock offset
  xen: Update sched clock offset to avoid system instability in
    hibernation

Munehisa Kamata (7):
  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-netfront: add callbacks for PM suspend and hibernation support
  xen-blkfront: add callbacks for PM suspend and hibernation
  xen/time: introduce xen_{save,restore}_steal_clock
  x86/xen: save and restore steal clock

 arch/x86/xen/enlighten_hvm.c      |   8 ++
 arch/x86/xen/suspend.c            |  72 ++++++++++++++++++
 arch/x86/xen/time.c               |  18 ++++-
 arch/x86/xen/xen-ops.h            |   3 +
 drivers/block/xen-blkfront.c      | 119 ++++++++++++++++++++++++++++--
 drivers/net/xen-netfront.c        |  98 +++++++++++++++++++++++-
 drivers/xen/events/events_base.c  |   1 +
 drivers/xen/manage.c              |  73 ++++++++++++++++++
 drivers/xen/time.c                |  29 +++++++-
 drivers/xen/xenbus/xenbus_probe.c |  99 ++++++++++++++++++++-----
 include/linux/irq.h               |   2 +
 include/xen/xen-ops.h             |   8 ++
 include/xen/xenbus.h              |   3 +
 kernel/irq/chip.c                 |   2 +-
 kernel/irq/internals.h            |   1 +
 kernel/irq/pm.c                   |  31 +++++---
 kernel/power/user.c               |   6 +-
 17 files changed, 533 insertions(+), 40 deletions(-)

-- 
2.24.1.AMZN


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

^ permalink raw reply	[flat|nested] 37+ messages in thread
* [Xen-devel] [RFC PATCH v3 06/12] xen-blkfront: add callbacks for PM suspend and hibernation
@ 2020-02-12 22:32 Anchal Agarwal
  0 siblings, 0 replies; 37+ messages in thread
From: Anchal Agarwal @ 2020-02-12 22:32 UTC (permalink / raw)
  To: tglx, mingo, bp, hpa, x86, boris.ostrovsky, jgross, linux-pm,
	linux-mm, kamatam, sstabellini, konrad.wilk, roger.pau, axboe,
	davem, rjw, len.brown, pavel, peterz, eduval, sblbir, anchalag,
	xen-devel, vkuznets, netdev, linux-kernel, dwmw, fllinden, benh

From: Munehisa Kamata <kamatam@amazon.com>

Add freeze, thaw and restore callbacks for PM suspend and hibernation
support. All frontend drivers that needs to use PM_HIBERNATION/PM_SUSPEND
events, need to implement these xenbus_driver callbacks.
The freeze handler stops a block-layer queue and disconnect the
frontend from the backend while freeing ring_info and associated resources.
The restore handler re-allocates ring_info and re-connect to the
backend, so the rest of the kernel can continue to use the block device
transparently. Also, the handlers are used for both PM suspend and
hibernation so that we can keep the existing suspend/resume callbacks for
Xen suspend without modification. Before disconnecting from backend,
we need to prevent any new IO from being queued and wait for existing
IO to complete. Freeze/unfreeze of the queues will guarantee that there
are no requests in use on the shared ring.

Note:For older backends,if a backend doesn't have commit'12ea729645ace'
xen/blkback: unmap all persistent grants when frontend gets disconnected,
the frontend may see massive amount of grant table warning when freeing
resources.
[   36.852659] deferring g.e. 0xf9 (pfn 0xffffffffffffffff)
[   36.855089] xen:grant_table: WARNING:e.g. 0x112 still in use!

In this case, persistent grants would need to be disabled.

[Anchal Changelog: Removed timeout/request during blkfront freeze.
Fixed major part of the code to work with blk-mq]
Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
Signed-off-by: Munehisa Kamata <kamatam@amazon.com>

---
Changes since V2: None
---
 drivers/block/xen-blkfront.c | 119 ++++++++++++++++++++++++++++++++---
 1 file changed, 112 insertions(+), 7 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 478120233750..d715ed3cb69a 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -47,6 +47,8 @@
 #include <linux/bitmap.h>
 #include <linux/list.h>
 #include <linux/workqueue.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
 
 #include <xen/xen.h>
 #include <xen/xenbus.h>
@@ -79,6 +81,8 @@ enum blkif_state {
 	BLKIF_STATE_DISCONNECTED,
 	BLKIF_STATE_CONNECTED,
 	BLKIF_STATE_SUSPENDED,
+	BLKIF_STATE_FREEZING,
+	BLKIF_STATE_FROZEN
 };
 
 struct grant {
@@ -220,6 +224,7 @@ struct blkfront_info
 	struct list_head requests;
 	struct bio_list bio_list;
 	struct list_head info_list;
+	struct completion wait_backend_disconnected;
 };
 
 static unsigned int nr_minors;
@@ -261,6 +266,7 @@ static DEFINE_SPINLOCK(minor_lock);
 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 static void blkfront_gather_backend_features(struct blkfront_info *info);
 static int negotiate_mq(struct blkfront_info *info);
+static void __blkif_free(struct blkfront_info *info);
 
 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 {
@@ -995,6 +1001,7 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 	info->sector_size = sector_size;
 	info->physical_sector_size = physical_sector_size;
 	blkif_set_queue_limits(info);
+	init_completion(&info->wait_backend_disconnected);
 
 	return 0;
 }
@@ -1218,6 +1225,8 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
 /* Already hold rinfo->ring_lock. */
 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
 {
+	if (unlikely(rinfo->dev_info->connected == BLKIF_STATE_FREEZING))
+		return;
 	if (!RING_FULL(&rinfo->ring))
 		blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
 }
@@ -1341,8 +1350,6 @@ static void blkif_free_ring(struct blkfront_ring_info *rinfo)
 
 static void blkif_free(struct blkfront_info *info, int suspend)
 {
-	unsigned int i;
-
 	/* Prevent new requests being issued until we fix things up. */
 	info->connected = suspend ?
 		BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
@@ -1350,6 +1357,13 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 	if (info->rq)
 		blk_mq_stop_hw_queues(info->rq);
 
+	__blkif_free(info);
+}
+
+static void __blkif_free(struct blkfront_info *info)
+{
+	unsigned int i;
+
 	for (i = 0; i < info->nr_rings; i++)
 		blkif_free_ring(&info->rinfo[i]);
 
@@ -1553,8 +1567,10 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
 	struct blkfront_info *info = rinfo->dev_info;
 
-	if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
-		return IRQ_HANDLED;
+	if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
+		if (info->connected != BLKIF_STATE_FREEZING)
+			return IRQ_HANDLED;
+	}
 
 	spin_lock_irqsave(&rinfo->ring_lock, flags);
  again:
@@ -2020,6 +2036,7 @@ static int blkif_recover(struct blkfront_info *info)
 	struct bio *bio;
 	unsigned int segs;
 
+	bool frozen = info->connected == BLKIF_STATE_FROZEN;
 	blkfront_gather_backend_features(info);
 	/* Reset limits changed by blk_mq_update_nr_hw_queues(). */
 	blkif_set_queue_limits(info);
@@ -2046,6 +2063,9 @@ static int blkif_recover(struct blkfront_info *info)
 		kick_pending_request_queues(rinfo);
 	}
 
+	if (frozen)
+		return 0;
+
 	list_for_each_entry_safe(req, n, &info->requests, queuelist) {
 		/* Requeue pending requests (flush or discard) */
 		list_del_init(&req->queuelist);
@@ -2359,6 +2379,7 @@ static void blkfront_connect(struct blkfront_info *info)
 
 		return;
 	case BLKIF_STATE_SUSPENDED:
+	case BLKIF_STATE_FROZEN:
 		/*
 		 * If we are recovering from suspension, we need to wait
 		 * for the backend to announce it's features before
@@ -2476,12 +2497,37 @@ static void blkback_changed(struct xenbus_device *dev,
 		break;
 
 	case XenbusStateClosed:
-		if (dev->state == XenbusStateClosed)
+		if (dev->state == XenbusStateClosed) {
+			if (info->connected == BLKIF_STATE_FREEZING) {
+				__blkif_free(info);
+				info->connected = BLKIF_STATE_FROZEN;
+				complete(&info->wait_backend_disconnected);
+				break;
+			}
+
 			break;
+		}
+
+		/*
+		 * We may somehow receive backend's Closed again while thawing
+		 * or restoring and it causes thawing or restoring to fail.
+		 * Ignore such unexpected state anyway.
+		 */
+		if (info->connected == BLKIF_STATE_FROZEN &&
+				dev->state == XenbusStateInitialised) {
+			dev_dbg(&dev->dev,
+					"ignore the backend's Closed state: %s",
+					dev->nodename);
+			break;
+		}
 		/* fall through */
 	case XenbusStateClosing:
-		if (info)
-			blkfront_closing(info);
+		if (info) {
+			if (info->connected == BLKIF_STATE_FREEZING)
+				xenbus_frontend_closed(dev);
+			else
+				blkfront_closing(info);
+		}
 		break;
 	}
 }
@@ -2625,6 +2671,62 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 	mutex_unlock(&blkfront_mutex);
 }
 
+static int blkfront_freeze(struct xenbus_device *dev)
+{
+	unsigned int i;
+	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
+	struct blkfront_ring_info *rinfo;
+	/* This would be reasonable timeout as used in xenbus_dev_shutdown() */
+	unsigned int timeout = 5 * HZ;
+	int err = 0;
+
+	info->connected = BLKIF_STATE_FREEZING;
+
+	blk_mq_freeze_queue(info->rq);
+	blk_mq_quiesce_queue(info->rq);
+
+	for (i = 0; i < info->nr_rings; i++) {
+		rinfo = &info->rinfo[i];
+
+		gnttab_cancel_free_callback(&rinfo->callback);
+		flush_work(&rinfo->work);
+	}
+
+	/* Kick the backend to disconnect */
+	xenbus_switch_state(dev, XenbusStateClosing);
+
+	/*
+	 * We don't want to move forward before the frontend is diconnected
+	 * from the backend cleanly.
+	 */
+	timeout = wait_for_completion_timeout(&info->wait_backend_disconnected,
+					      timeout);
+	if (!timeout) {
+		err = -EBUSY;
+		xenbus_dev_error(dev, err, "Freezing timed out;"
+				 "the device may become inconsistent state");
+	}
+
+	return err;
+}
+
+static int blkfront_restore(struct xenbus_device *dev)
+{
+	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
+	int err = 0;
+
+	err = talk_to_blkback(dev, info);
+	blk_mq_unquiesce_queue(info->rq);
+	blk_mq_unfreeze_queue(info->rq);
+
+	if (err)
+		goto out;
+	blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
+
+out:
+	return err;
+}
+
 static const struct block_device_operations xlvbd_block_fops =
 {
 	.owner = THIS_MODULE,
@@ -2647,6 +2749,9 @@ static struct xenbus_driver blkfront_driver = {
 	.resume = blkfront_resume,
 	.otherend_changed = blkback_changed,
 	.is_ready = blkfront_is_ready,
+	.freeze = blkfront_freeze,
+	.thaw = blkfront_restore,
+	.restore = blkfront_restore
 };
 
 static void purge_persistent_grants(struct blkfront_info *info)
-- 
2.24.1.AMZN


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

^ permalink raw reply	[flat|nested] 37+ messages in thread

end of thread, back to index

Thread overview: 37+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-02-14 23:21 [Xen-devel] [RFC RESEND PATCH v3 00/12] Enable PM hibernation on guest VMs Anchal Agarwal
2020-02-14 23:22 ` [Xen-devel] [RFC PATCH v3 01/12] xen/manage: keep track of the on-going suspend mode Anchal Agarwal
2020-02-14 23:23 ` [Xen-devel] [RFC PATCH v3 02/12] xenbus: add freeze/thaw/restore callbacks support Anchal Agarwal
2020-02-14 23:23 ` [Xen-devel] [RFC PATCH v3 03/12] x86/xen: Introduce new function to map HYPERVISOR_shared_info on Resume Anchal Agarwal
2020-02-14 23:24 ` [Xen-devel] [RFC PATCH v3 04/12] x86/xen: add system core suspend and resume callbacks Anchal Agarwal
2020-02-14 23:24 ` [Xen-devel] [RFC PATCH v3 05/12] xen-netfront: add callbacks for PM suspend and hibernation support Anchal Agarwal
2020-02-14 23:25 ` [Xen-devel] [RFC PATCH v3 06/12] xen-blkfront: add callbacks for PM suspend and hibernation Anchal Agarwal
2020-02-17 10:05   ` Roger Pau Monné
2020-02-17 23:05     ` Anchal Agarwal
2020-02-18  9:16       ` Roger Pau Monné
2020-02-19 18:04         ` Anchal Agarwal
2020-02-20  8:39           ` Roger Pau Monné
2020-02-20  8:54             ` Durrant, Paul
2020-02-20 15:45               ` Roger Pau Monné
2020-02-20 16:23                 ` Durrant, Paul
2020-02-20 16:48                   ` Roger Pau Monné
2020-02-20 17:01                     ` Durrant, Paul
2020-02-21  0:49                       ` Anchal Agarwal
2020-02-21  9:47                         ` Roger Pau Monné
2020-02-21  9:22                       ` Roger Pau Monné
2020-02-21  9:56                         ` Durrant, Paul
2020-02-21 10:21                           ` Roger Pau Monné
2020-02-21 10:33                             ` Durrant, Paul
2020-02-21 11:51                               ` Roger Pau Monné
2020-02-21 14:24   ` Roger Pau Monné
2020-03-06 18:40     ` Anchal Agarwal
2020-03-09  9:54       ` Roger Pau Monné
     [not found]         ` <FA688A68-5372-4757-B075-A69A45671CB9@amazon.com>
     [not found]           ` <20200312090435.GK24449@Air-de-Roger.citrite.net>
2020-03-13 17:21             ` Anchal Agarwal
2020-02-14 23:25 ` [Xen-devel] [RFC PATCH v3 07/12] genirq: Shutdown irq chips in suspend/resume during hibernation Anchal Agarwal
2020-03-06 23:03   ` Thomas Gleixner
2020-03-09 22:37     ` [Xen-devel] [EXTERNAL][RFC " Anchal Agarwal
2020-02-14 23:26 ` [Xen-devel] [RFC PATCH v3 08/12] xen/time: introduce xen_{save, restore}_steal_clock Anchal Agarwal
2020-02-14 23:27 ` [Xen-devel] [RFC PATCH v3 09/12] x86/xen: save and restore steal clock Anchal Agarwal
2020-02-14 23:27 ` [Xen-devel] [RFC PATCH v3 10/12] xen: Introduce wrapper for save/restore sched clock offset Anchal Agarwal
2020-02-14 23:27 ` [Xen-devel] [RFC PATCH v3 11/12] xen: Update sched clock offset to avoid system instability in hibernation Anchal Agarwal
2020-02-14 23:28 ` [Xen-devel] [RFC PATCH v3 12/12] PM / hibernate: update the resume offset on SNAPSHOT_SET_SWAP_AREA Anchal Agarwal
  -- strict thread matches above, loose matches on Subject: below --
2020-02-12 22:32 [Xen-devel] [RFC PATCH v3 06/12] xen-blkfront: add callbacks for PM suspend and hibernation Anchal Agarwal

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