[PULL 00/24] bitmaps patches for -rc2, 2020-07-27

[PULL 00/24] bitmaps patches for -rc2, 2020-07-27

[Eric Blake]

The following changes since commit 9303ecb658a0194560d1eecde165a1511223c2d8:

  Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20200727' into staging (2020-07-27 17:25:06 +0100)

are available in the Git repository at:

  https://repo.or.cz/qemu/ericb.git tags/pull-bitmaps-2020-07-27

for you to fetch changes up to 37931e006f05cb768b78dcc47453b13f76ea43c5:

  migration: Fix typos in bitmap migration comments (2020-07-27 15:42:21 -0500)

----------------------------------------------------------------
bitmaps patches for 2020-07-27

- Improve handling of various post-copy bitmap migration scenarios. A lost
bitmap should merely mean that the next backup must be full rather than
incremental, rather than abruptly breaking the entire guest migration.
- Associated iotest improvements

----------------------------------------------------------------
Andrey Shinkevich (1):
      qcow2: Fix capitalization of header extension constant.

Eric Blake (2):
      iotests: Adjust which migration tests are quick
      migration: Fix typos in bitmap migration comments

Vladimir Sementsov-Ogievskiy (21):
      qemu-iotests/199: fix style
      qemu-iotests/199: drop extra constraints
      qemu-iotests/199: better catch postcopy time
      qemu-iotests/199: improve performance: set bitmap by discard
      qemu-iotests/199: change discard patterns
      qemu-iotests/199: increase postcopy period
      migration/block-dirty-bitmap: fix dirty_bitmap_mig_before_vm_start
      migration/block-dirty-bitmap: rename state structure types
      migration/block-dirty-bitmap: rename dirty_bitmap_mig_cleanup
      migration/block-dirty-bitmap: move mutex init to dirty_bitmap_mig_init
      migration/block-dirty-bitmap: refactor state global variables
      migration/block-dirty-bitmap: rename finish_lock to just lock
      migration/block-dirty-bitmap: simplify dirty_bitmap_load_complete
      migration/block-dirty-bitmap: keep bitmap state for all bitmaps
      migration/block-dirty-bitmap: relax error handling in incoming part
      migration/block-dirty-bitmap: cancel migration on shutdown
      migration/savevm: don't worry if bitmap migration postcopy failed
      qemu-iotests/199: prepare for new test-cases addition
      qemu-iotests/199: check persistent bitmaps
      qemu-iotests/199: add early shutdown case to bitmaps postcopy
      qemu-iotests/199: add source-killed case to bitmaps postcopy

 docs/interop/qcow2.txt         |   2 +-
 migration/migration.h          |   3 +-
 block/qcow2.c                  |   2 +-
 migration/block-dirty-bitmap.c | 472 ++++++++++++++++++++++++++---------------
 migration/migration.c          |  15 +-
 migration/savevm.c             |  37 +++-
 tests/qemu-iotests/199         | 254 +++++++++++++++++-----
 tests/qemu-iotests/199.out     |   4 +-
 tests/qemu-iotests/group       |  12 +-
 9 files changed, 556 insertions(+), 245 deletions(-)

-- 
2.27.0

[PULL 01/24] qcow2: Fix capitalization of header extension constant.

[Eric Blake]

From: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>

Make the capitalization of the hexadecimal numbers consistent for the
QCOW2 header extension constants in docs/interop/qcow2.txt.

Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <1594973699-781898-2-git-send-email-andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 docs/interop/qcow2.txt | 2 +-
 block/qcow2.c          | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt
index cb723463f241..f072e27900e6 100644
--- a/docs/interop/qcow2.txt
+++ b/docs/interop/qcow2.txt
@@ -231,7 +231,7 @@ be stored. Each extension has a structure like the following:

     Byte  0 -  3:   Header extension type:
                         0x00000000 - End of the header extension area
-                        0xE2792ACA - Backing file format name string
+                        0xe2792aca - Backing file format name string
                         0x6803f857 - Feature name table
                         0x23852875 - Bitmaps extension
                         0x0537be77 - Full disk encryption header pointer
diff --git a/block/qcow2.c b/block/qcow2.c
index fadf3422f8c5..6ad6bdc166ea 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -66,7 +66,7 @@ typedef struct {
 } QEMU_PACKED QCowExtension;

 #define  QCOW2_EXT_MAGIC_END 0
-#define  QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
+#define  QCOW2_EXT_MAGIC_BACKING_FORMAT 0xe2792aca
 #define  QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
 #define  QCOW2_EXT_MAGIC_CRYPTO_HEADER 0x0537be77
 #define  QCOW2_EXT_MAGIC_BITMAPS 0x23852875
-- 
2.27.0

[PULL 02/24] qemu-iotests/199: fix style

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Mostly, satisfy pep8 complaints.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-2-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index 40774eed74c2..de9ba8d94c23 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -28,8 +28,8 @@ disk_b = os.path.join(iotests.test_dir, 'disk_b')
 size = '256G'
 fifo = os.path.join(iotests.test_dir, 'mig_fifo')

+
 class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
-
     def tearDown(self):
         self.vm_a.shutdown()
         self.vm_b.shutdown()
@@ -54,7 +54,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):

         result = self.vm_a.qmp('block-dirty-bitmap-add', node='drive0',
                                name='bitmap', granularity=granularity)
-        self.assert_qmp(result, 'return', {});
+        self.assert_qmp(result, 'return', {})

         s = 0
         while s < write_size:
@@ -71,7 +71,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):

         result = self.vm_a.qmp('block-dirty-bitmap-clear', node='drive0',
                                name='bitmap')
-        self.assert_qmp(result, 'return', {});
+        self.assert_qmp(result, 'return', {})
         s = 0
         while s < write_size:
             self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
@@ -104,15 +104,16 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
             self.vm_b.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
             s += 0x10000

-        result = self.vm_b.qmp('query-block');
+        result = self.vm_b.qmp('query-block')
         while len(result['return'][0]['dirty-bitmaps']) > 1:
             time.sleep(2)
-            result = self.vm_b.qmp('query-block');
+            result = self.vm_b.qmp('query-block')

         result = self.vm_b.qmp('x-debug-block-dirty-bitmap-sha256',
                                node='drive0', name='bitmap')

-        self.assert_qmp(result, 'return/sha256', sha256);
+        self.assert_qmp(result, 'return/sha256', sha256)
+

 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2'], supported_cache_modes=['none'],
-- 
2.27.0

[PULL 03/24] qemu-iotests/199: drop extra constraints

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

We don't need any specific format constraints here. Still keep qcow2
for two reasons:
1. No extra calls of format-unrelated test
2. Add some check around persistent bitmap in future (require qcow2)

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-3-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index de9ba8d94c23..dda918450a8b 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -116,5 +116,4 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):


 if __name__ == '__main__':
-    iotests.main(supported_fmts=['qcow2'], supported_cache_modes=['none'],
-                 supported_protocols=['file'])
+    iotests.main(supported_fmts=['qcow2'])
-- 
2.27.0

[PULL 04/24] qemu-iotests/199: better catch postcopy time

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

The test aims to test _postcopy_ migration, and wants to do some write
operations during postcopy time.

Test considers migrate status=complete event on source as start of
postcopy. This is completely wrong, completion is completion of the
whole migration process. Let's instead consider destination start as
start of postcopy, and use RESUME event for it.

Next, as migration finish, let's use migration status=complete event on
target, as such method is closer to what libvirt or another user will
do, than tracking number of dirty-bitmaps.

Finally, add a possibility to dump events for debug. And if
set debug to True, we see, that actual postcopy period is very small
relatively to the whole test duration time (~0.2 seconds to >40 seconds
for me). This means, that test is very inefficient in what it supposed
to do. Let's improve it in following commits.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-4-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 72 +++++++++++++++++++++++++++++++++---------
 1 file changed, 57 insertions(+), 15 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index dda918450a8b..dd6044768c76 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -20,17 +20,43 @@

 import os
 import iotests
-import time
 from iotests import qemu_img

+debug = False
+
 disk_a = os.path.join(iotests.test_dir, 'disk_a')
 disk_b = os.path.join(iotests.test_dir, 'disk_b')
 size = '256G'
 fifo = os.path.join(iotests.test_dir, 'mig_fifo')


+def event_seconds(event):
+    return event['timestamp']['seconds'] + \
+        event['timestamp']['microseconds'] / 1000000.0
+
+
+def event_dist(e1, e2):
+    return event_seconds(e2) - event_seconds(e1)
+
+
 class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
     def tearDown(self):
+        if debug:
+            self.vm_a_events += self.vm_a.get_qmp_events()
+            self.vm_b_events += self.vm_b.get_qmp_events()
+            for e in self.vm_a_events:
+                e['vm'] = 'SRC'
+            for e in self.vm_b_events:
+                e['vm'] = 'DST'
+            events = (self.vm_a_events + self.vm_b_events)
+            events = [(e['timestamp']['seconds'],
+                       e['timestamp']['microseconds'],
+                       e['vm'],
+                       e['event'],
+                       e.get('data', '')) for e in events]
+            for e in sorted(events):
+                print('{}.{:06} {} {} {}'.format(*e))
+
         self.vm_a.shutdown()
         self.vm_b.shutdown()
         os.remove(disk_a)
@@ -47,6 +73,10 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         self.vm_a.launch()
         self.vm_b.launch()

+        # collect received events for debug
+        self.vm_a_events = []
+        self.vm_b_events = []
+
     def test_postcopy(self):
         write_size = 0x40000000
         granularity = 512
@@ -77,15 +107,13 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
             self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
             s += 0x10000

-        bitmaps_cap = {'capability': 'dirty-bitmaps', 'state': True}
-        events_cap = {'capability': 'events', 'state': True}
+        caps = [{'capability': 'dirty-bitmaps', 'state': True},
+                {'capability': 'events', 'state': True}]

-        result = self.vm_a.qmp('migrate-set-capabilities',
-                               capabilities=[bitmaps_cap, events_cap])
+        result = self.vm_a.qmp('migrate-set-capabilities', capabilities=caps)
         self.assert_qmp(result, 'return', {})

-        result = self.vm_b.qmp('migrate-set-capabilities',
-                               capabilities=[bitmaps_cap])
+        result = self.vm_b.qmp('migrate-set-capabilities', capabilities=caps)
         self.assert_qmp(result, 'return', {})

         result = self.vm_a.qmp('migrate', uri='exec:cat>' + fifo)
@@ -94,24 +122,38 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         result = self.vm_a.qmp('migrate-start-postcopy')
         self.assert_qmp(result, 'return', {})

-        while True:
-            event = self.vm_a.event_wait('MIGRATION')
-            if event['data']['status'] == 'completed':
-                break
+        event_resume = self.vm_b.event_wait('RESUME')
+        self.vm_b_events.append(event_resume)

         s = 0x8000
         while s < write_size:
             self.vm_b.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
             s += 0x10000

+        match = {'data': {'status': 'completed'}}
+        event_complete = self.vm_b.event_wait('MIGRATION', match=match)
+        self.vm_b_events.append(event_complete)
+
+        # take queued event, should already been happened
+        event_stop = self.vm_a.event_wait('STOP')
+        self.vm_a_events.append(event_stop)
+
+        downtime = event_dist(event_stop, event_resume)
+        postcopy_time = event_dist(event_resume, event_complete)
+
+        # TODO: assert downtime * 10 < postcopy_time
+        if debug:
+            print('downtime:', downtime)
+            print('postcopy_time:', postcopy_time)
+
+        # Assert that bitmap migration is finished (check that successor bitmap
+        # is removed)
         result = self.vm_b.qmp('query-block')
-        while len(result['return'][0]['dirty-bitmaps']) > 1:
-            time.sleep(2)
-            result = self.vm_b.qmp('query-block')
+        assert len(result['return'][0]['dirty-bitmaps']) == 1

+        # Check content of migrated (and updated by new writes) bitmap
         result = self.vm_b.qmp('x-debug-block-dirty-bitmap-sha256',
                                node='drive0', name='bitmap')
-
         self.assert_qmp(result, 'return/sha256', sha256)


-- 
2.27.0

[PULL 05/24] qemu-iotests/199: improve performance: set bitmap by discard

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Discard dirties dirty-bitmap as well as write, but works faster. Let's
use it instead.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-5-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index dd6044768c76..190e820b8408 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -67,8 +67,10 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         os.mkfifo(fifo)
         qemu_img('create', '-f', iotests.imgfmt, disk_a, size)
         qemu_img('create', '-f', iotests.imgfmt, disk_b, size)
-        self.vm_a = iotests.VM(path_suffix='a').add_drive(disk_a)
-        self.vm_b = iotests.VM(path_suffix='b').add_drive(disk_b)
+        self.vm_a = iotests.VM(path_suffix='a').add_drive(disk_a,
+                                                          'discard=unmap')
+        self.vm_b = iotests.VM(path_suffix='b').add_drive(disk_b,
+                                                          'discard=unmap')
         self.vm_b.add_incoming("exec: cat '" + fifo + "'")
         self.vm_a.launch()
         self.vm_b.launch()
@@ -78,7 +80,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         self.vm_b_events = []

     def test_postcopy(self):
-        write_size = 0x40000000
+        discard_size = 0x40000000
         granularity = 512
         chunk = 4096

@@ -86,25 +88,32 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
                                name='bitmap', granularity=granularity)
         self.assert_qmp(result, 'return', {})

+        result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
+                               node='drive0', name='bitmap')
+        empty_sha256 = result['return']['sha256']
+
         s = 0
-        while s < write_size:
-            self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+        while s < discard_size:
+            self.vm_a.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
             s += 0x10000
         s = 0x8000
-        while s < write_size:
-            self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+        while s < discard_size:
+            self.vm_a.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
             s += 0x10000

         result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
                                node='drive0', name='bitmap')
         sha256 = result['return']['sha256']

+        # Check, that updating the bitmap by discards works
+        assert sha256 != empty_sha256
+
         result = self.vm_a.qmp('block-dirty-bitmap-clear', node='drive0',
                                name='bitmap')
         self.assert_qmp(result, 'return', {})
         s = 0
-        while s < write_size:
-            self.vm_a.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+        while s < discard_size:
+            self.vm_a.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
             s += 0x10000

         caps = [{'capability': 'dirty-bitmaps', 'state': True},
@@ -126,8 +135,8 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         self.vm_b_events.append(event_resume)

         s = 0x8000
-        while s < write_size:
-            self.vm_b.hmp_qemu_io('drive0', 'write %d %d' % (s, chunk))
+        while s < discard_size:
+            self.vm_b.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
             s += 0x10000

         match = {'data': {'status': 'completed'}}
-- 
2.27.0

[PULL 06/24] qemu-iotests/199: change discard patterns

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

iotest 199 works too long because of many discard operations. At the
same time, postcopy period is very short, in spite of all these
efforts.

So, let's use less discards (and with more interesting patterns) to
reduce test timing. In the next commit we'll increase postcopy period.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-6-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 44 +++++++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index 190e820b8408..da4dae01fb5d 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -30,6 +30,28 @@ size = '256G'
 fifo = os.path.join(iotests.test_dir, 'mig_fifo')


+GiB = 1024 * 1024 * 1024
+
+discards1 = (
+    (0, GiB),
+    (2 * GiB + 512 * 5, 512),
+    (3 * GiB + 512 * 5, 512),
+    (100 * GiB, GiB)
+)
+
+discards2 = (
+    (3 * GiB + 512 * 8, 512),
+    (4 * GiB + 512 * 8, 512),
+    (50 * GiB, GiB),
+    (100 * GiB + GiB // 2, GiB)
+)
+
+
+def apply_discards(vm, discards):
+    for d in discards:
+        vm.hmp_qemu_io('drive0', 'discard {} {}'.format(*d))
+
+
 def event_seconds(event):
     return event['timestamp']['seconds'] + \
         event['timestamp']['microseconds'] / 1000000.0
@@ -80,9 +102,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         self.vm_b_events = []

     def test_postcopy(self):
-        discard_size = 0x40000000
         granularity = 512
-        chunk = 4096

         result = self.vm_a.qmp('block-dirty-bitmap-add', node='drive0',
                                name='bitmap', granularity=granularity)
@@ -92,14 +112,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
                                node='drive0', name='bitmap')
         empty_sha256 = result['return']['sha256']

-        s = 0
-        while s < discard_size:
-            self.vm_a.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
-            s += 0x10000
-        s = 0x8000
-        while s < discard_size:
-            self.vm_a.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
-            s += 0x10000
+        apply_discards(self.vm_a, discards1 + discards2)

         result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
                                node='drive0', name='bitmap')
@@ -111,10 +124,8 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         result = self.vm_a.qmp('block-dirty-bitmap-clear', node='drive0',
                                name='bitmap')
         self.assert_qmp(result, 'return', {})
-        s = 0
-        while s < discard_size:
-            self.vm_a.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
-            s += 0x10000
+
+        apply_discards(self.vm_a, discards1)

         caps = [{'capability': 'dirty-bitmaps', 'state': True},
                 {'capability': 'events', 'state': True}]
@@ -134,10 +145,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         event_resume = self.vm_b.event_wait('RESUME')
         self.vm_b_events.append(event_resume)

-        s = 0x8000
-        while s < discard_size:
-            self.vm_b.hmp_qemu_io('drive0', 'discard %d %d' % (s, chunk))
-            s += 0x10000
+        apply_discards(self.vm_b, discards2)

         match = {'data': {'status': 'completed'}}
         event_complete = self.vm_b.event_wait('MIGRATION', match=match)
-- 
2.27.0

[PULL 07/24] qemu-iotests/199: increase postcopy period

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

The test wants to force a bitmap postcopy. Still, the resulting
postcopy period is very small. Let's increase it by adding more
bitmaps to migrate. Also, test disabled bitmaps migration.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-7-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 66 +++++++++++++++++++++++++++---------------
 1 file changed, 43 insertions(+), 23 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index da4dae01fb5d..d8532e49da00 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -103,30 +103,46 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):

     def test_postcopy(self):
         granularity = 512
+        nb_bitmaps = 15

-        result = self.vm_a.qmp('block-dirty-bitmap-add', node='drive0',
-                               name='bitmap', granularity=granularity)
-        self.assert_qmp(result, 'return', {})
+        for i in range(nb_bitmaps):
+            result = self.vm_a.qmp('block-dirty-bitmap-add', node='drive0',
+                                   name='bitmap{}'.format(i),
+                                   granularity=granularity)
+            self.assert_qmp(result, 'return', {})

         result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
-                               node='drive0', name='bitmap')
+                               node='drive0', name='bitmap0')
         empty_sha256 = result['return']['sha256']

-        apply_discards(self.vm_a, discards1 + discards2)
-
-        result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
-                               node='drive0', name='bitmap')
-        sha256 = result['return']['sha256']
-
-        # Check, that updating the bitmap by discards works
-        assert sha256 != empty_sha256
-
-        result = self.vm_a.qmp('block-dirty-bitmap-clear', node='drive0',
-                               name='bitmap')
-        self.assert_qmp(result, 'return', {})
-
         apply_discards(self.vm_a, discards1)

+        result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
+                               node='drive0', name='bitmap0')
+        discards1_sha256 = result['return']['sha256']
+
+        # Check, that updating the bitmap by discards works
+        assert discards1_sha256 != empty_sha256
+
+        # We want to calculate resulting sha256. Do it in bitmap0, so, disable
+        # other bitmaps
+        for i in range(1, nb_bitmaps):
+            result = self.vm_a.qmp('block-dirty-bitmap-disable', node='drive0',
+                                   name='bitmap{}'.format(i))
+            self.assert_qmp(result, 'return', {})
+
+        apply_discards(self.vm_a, discards2)
+
+        result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
+                               node='drive0', name='bitmap0')
+        all_discards_sha256 = result['return']['sha256']
+
+        # Now, enable some bitmaps, to be updated during migration
+        for i in range(2, nb_bitmaps, 2):
+            result = self.vm_a.qmp('block-dirty-bitmap-enable', node='drive0',
+                                   name='bitmap{}'.format(i))
+            self.assert_qmp(result, 'return', {})
+
         caps = [{'capability': 'dirty-bitmaps', 'state': True},
                 {'capability': 'events', 'state': True}]

@@ -145,6 +161,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         event_resume = self.vm_b.event_wait('RESUME')
         self.vm_b_events.append(event_resume)

+        # enabled bitmaps should be updated
         apply_discards(self.vm_b, discards2)

         match = {'data': {'status': 'completed'}}
@@ -158,7 +175,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         downtime = event_dist(event_stop, event_resume)
         postcopy_time = event_dist(event_resume, event_complete)

-        # TODO: assert downtime * 10 < postcopy_time
+        assert downtime * 10 < postcopy_time
         if debug:
             print('downtime:', downtime)
             print('postcopy_time:', postcopy_time)
@@ -166,12 +183,15 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         # Assert that bitmap migration is finished (check that successor bitmap
         # is removed)
         result = self.vm_b.qmp('query-block')
-        assert len(result['return'][0]['dirty-bitmaps']) == 1
+        assert len(result['return'][0]['dirty-bitmaps']) == nb_bitmaps

-        # Check content of migrated (and updated by new writes) bitmap
-        result = self.vm_b.qmp('x-debug-block-dirty-bitmap-sha256',
-                               node='drive0', name='bitmap')
-        self.assert_qmp(result, 'return/sha256', sha256)
+        # Check content of migrated bitmaps. Still, don't waste time checking
+        # every bitmap
+        for i in range(0, nb_bitmaps, 5):
+            result = self.vm_b.qmp('x-debug-block-dirty-bitmap-sha256',
+                                   node='drive0', name='bitmap{}'.format(i))
+            sha256 = discards1_sha256 if i % 2 else all_discards_sha256
+            self.assert_qmp(result, 'return/sha256', sha256)


 if __name__ == '__main__':
-- 
2.27.0

[PULL 08/24] migration/block-dirty-bitmap: fix dirty_bitmap_mig_before_vm_start

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Using the _locked version of bdrv_enable_dirty_bitmap to bypass locking
is wrong as we do not already own the mutex.  Moreover, the adjacent
call to bdrv_dirty_bitmap_enable_successor grabs the mutex.

Fixes: 58f72b965e9e1q
Cc: qemu-stable@nongnu.org # v3.0
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-8-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index b0dbf9eeed43..0739f1259e05 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -566,7 +566,7 @@ void dirty_bitmap_mig_before_vm_start(void)
         DirtyBitmapLoadBitmapState *b = item->data;

         if (b->migrated) {
-            bdrv_enable_dirty_bitmap_locked(b->bitmap);
+            bdrv_enable_dirty_bitmap(b->bitmap);
         } else {
             bdrv_dirty_bitmap_enable_successor(b->bitmap);
         }
-- 
2.27.0

[PULL 09/24] migration/block-dirty-bitmap: rename state structure types

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Rename types to be symmetrical for load/save part and shorter.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-9-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 70 ++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 33 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 0739f1259e05..1d57bff4f6c7 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -100,23 +100,25 @@
 /* 0x04 was "AUTOLOAD" flags on elder versions, no it is ignored */
 #define DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK    0xf8

-typedef struct DirtyBitmapMigBitmapState {
+/* State of one bitmap during save process */
+typedef struct SaveBitmapState {
     /* Written during setup phase. */
     BlockDriverState *bs;
     const char *node_name;
     BdrvDirtyBitmap *bitmap;
     uint64_t total_sectors;
     uint64_t sectors_per_chunk;
-    QSIMPLEQ_ENTRY(DirtyBitmapMigBitmapState) entry;
+    QSIMPLEQ_ENTRY(SaveBitmapState) entry;
     uint8_t flags;

     /* For bulk phase. */
     bool bulk_completed;
     uint64_t cur_sector;
-} DirtyBitmapMigBitmapState;
+} SaveBitmapState;

-typedef struct DirtyBitmapMigState {
-    QSIMPLEQ_HEAD(, DirtyBitmapMigBitmapState) dbms_list;
+/* State of the dirty bitmap migration (DBM) during save process */
+typedef struct DBMSaveState {
+    QSIMPLEQ_HEAD(, SaveBitmapState) dbms_list;

     bool bulk_completed;
     bool no_bitmaps;
@@ -124,23 +126,25 @@ typedef struct DirtyBitmapMigState {
     /* for send_bitmap_bits() */
     BlockDriverState *prev_bs;
     BdrvDirtyBitmap *prev_bitmap;
-} DirtyBitmapMigState;
+} DBMSaveState;

-typedef struct DirtyBitmapLoadState {
+/* State of the dirty bitmap migration (DBM) during load process */
+typedef struct DBMLoadState {
     uint32_t flags;
     char node_name[256];
     char bitmap_name[256];
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
-} DirtyBitmapLoadState;
+} DBMLoadState;

-static DirtyBitmapMigState dirty_bitmap_mig_state;
+static DBMSaveState dirty_bitmap_mig_state;

-typedef struct DirtyBitmapLoadBitmapState {
+/* State of one bitmap during load process */
+typedef struct LoadBitmapState {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
     bool migrated;
-} DirtyBitmapLoadBitmapState;
+} LoadBitmapState;
 static GSList *enabled_bitmaps;
 QemuMutex finish_lock;

@@ -170,7 +174,7 @@ static void qemu_put_bitmap_flags(QEMUFile *f, uint32_t flags)
     qemu_put_byte(f, flags);
 }

-static void send_bitmap_header(QEMUFile *f, DirtyBitmapMigBitmapState *dbms,
+static void send_bitmap_header(QEMUFile *f, SaveBitmapState *dbms,
                                uint32_t additional_flags)
 {
     BlockDriverState *bs = dbms->bs;
@@ -199,19 +203,19 @@ static void send_bitmap_header(QEMUFile *f, DirtyBitmapMigBitmapState *dbms,
     }
 }

-static void send_bitmap_start(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
+static void send_bitmap_start(QEMUFile *f, SaveBitmapState *dbms)
 {
     send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_START);
     qemu_put_be32(f, bdrv_dirty_bitmap_granularity(dbms->bitmap));
     qemu_put_byte(f, dbms->flags);
 }

-static void send_bitmap_complete(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
+static void send_bitmap_complete(QEMUFile *f, SaveBitmapState *dbms)
 {
     send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
 }

-static void send_bitmap_bits(QEMUFile *f, DirtyBitmapMigBitmapState *dbms,
+static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,
                              uint64_t start_sector, uint32_t nr_sectors)
 {
     /* align for buffer_is_zero() */
@@ -257,7 +261,7 @@ static void send_bitmap_bits(QEMUFile *f, DirtyBitmapMigBitmapState *dbms,
 /* Called with iothread lock taken.  */
 static void dirty_bitmap_mig_cleanup(void)
 {
-    DirtyBitmapMigBitmapState *dbms;
+    SaveBitmapState *dbms;

     while ((dbms = QSIMPLEQ_FIRST(&dirty_bitmap_mig_state.dbms_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&dirty_bitmap_mig_state.dbms_list, entry);
@@ -271,7 +275,7 @@ static void dirty_bitmap_mig_cleanup(void)
 static int add_bitmaps_to_list(BlockDriverState *bs, const char *bs_name)
 {
     BdrvDirtyBitmap *bitmap;
-    DirtyBitmapMigBitmapState *dbms;
+    SaveBitmapState *dbms;
     Error *local_err = NULL;

     FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
@@ -309,7 +313,7 @@ static int add_bitmaps_to_list(BlockDriverState *bs, const char *bs_name)
         bdrv_ref(bs);
         bdrv_dirty_bitmap_set_busy(bitmap, true);

-        dbms = g_new0(DirtyBitmapMigBitmapState, 1);
+        dbms = g_new0(SaveBitmapState, 1);
         dbms->bs = bs;
         dbms->node_name = bs_name;
         dbms->bitmap = bitmap;
@@ -334,7 +338,7 @@ static int add_bitmaps_to_list(BlockDriverState *bs, const char *bs_name)
 static int init_dirty_bitmap_migration(void)
 {
     BlockDriverState *bs;
-    DirtyBitmapMigBitmapState *dbms;
+    SaveBitmapState *dbms;
     GHashTable *handled_by_blk = g_hash_table_new(NULL, NULL);
     BlockBackend *blk;

@@ -408,7 +412,7 @@ fail:
 }

 /* Called with no lock taken.  */
-static void bulk_phase_send_chunk(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
+static void bulk_phase_send_chunk(QEMUFile *f, SaveBitmapState *dbms)
 {
     uint32_t nr_sectors = MIN(dbms->total_sectors - dbms->cur_sector,
                              dbms->sectors_per_chunk);
@@ -424,7 +428,7 @@ static void bulk_phase_send_chunk(QEMUFile *f, DirtyBitmapMigBitmapState *dbms)
 /* Called with no lock taken.  */
 static void bulk_phase(QEMUFile *f, bool limit)
 {
-    DirtyBitmapMigBitmapState *dbms;
+    SaveBitmapState *dbms;

     QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
         while (!dbms->bulk_completed) {
@@ -461,7 +465,7 @@ static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)

 static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
 {
-    DirtyBitmapMigBitmapState *dbms;
+    SaveBitmapState *dbms;
     trace_dirty_bitmap_save_complete_enter();

     if (!dirty_bitmap_mig_state.bulk_completed) {
@@ -486,7 +490,7 @@ static void dirty_bitmap_save_pending(QEMUFile *f, void *opaque,
                                       uint64_t *res_compatible,
                                       uint64_t *res_postcopy_only)
 {
-    DirtyBitmapMigBitmapState *dbms;
+    SaveBitmapState *dbms;
     uint64_t pending = 0;

     qemu_mutex_lock_iothread();
@@ -507,7 +511,7 @@ static void dirty_bitmap_save_pending(QEMUFile *f, void *opaque,
 }

 /* First occurrence of this bitmap. It should be created if doesn't exist */
-static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
+static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
 {
     Error *local_err = NULL;
     uint32_t granularity = qemu_get_be32(f);
@@ -538,7 +542,7 @@ static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)

     bdrv_disable_dirty_bitmap(s->bitmap);
     if (flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED) {
-        DirtyBitmapLoadBitmapState *b;
+        LoadBitmapState *b;

         bdrv_dirty_bitmap_create_successor(s->bitmap, &local_err);
         if (local_err) {
@@ -546,7 +550,7 @@ static int dirty_bitmap_load_start(QEMUFile *f, DirtyBitmapLoadState *s)
             return -EINVAL;
         }

-        b = g_new(DirtyBitmapLoadBitmapState, 1);
+        b = g_new(LoadBitmapState, 1);
         b->bs = s->bs;
         b->bitmap = s->bitmap;
         b->migrated = false;
@@ -563,7 +567,7 @@ void dirty_bitmap_mig_before_vm_start(void)
     qemu_mutex_lock(&finish_lock);

     for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
-        DirtyBitmapLoadBitmapState *b = item->data;
+        LoadBitmapState *b = item->data;

         if (b->migrated) {
             bdrv_enable_dirty_bitmap(b->bitmap);
@@ -580,7 +584,7 @@ void dirty_bitmap_mig_before_vm_start(void)
     qemu_mutex_unlock(&finish_lock);
 }

-static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
+static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
 {
     GSList *item;
     trace_dirty_bitmap_load_complete();
@@ -589,7 +593,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
     qemu_mutex_lock(&finish_lock);

     for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
-        DirtyBitmapLoadBitmapState *b = item->data;
+        LoadBitmapState *b = item->data;

         if (b->bitmap == s->bitmap) {
             b->migrated = true;
@@ -621,7 +625,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DirtyBitmapLoadState *s)
     qemu_mutex_unlock(&finish_lock);
 }

-static int dirty_bitmap_load_bits(QEMUFile *f, DirtyBitmapLoadState *s)
+static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
 {
     uint64_t first_byte = qemu_get_be64(f) << BDRV_SECTOR_BITS;
     uint64_t nr_bytes = (uint64_t)qemu_get_be32(f) << BDRV_SECTOR_BITS;
@@ -666,7 +670,7 @@ static int dirty_bitmap_load_bits(QEMUFile *f, DirtyBitmapLoadState *s)
     return 0;
 }

-static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)
+static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s)
 {
     Error *local_err = NULL;
     bool nothing;
@@ -715,7 +719,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DirtyBitmapLoadState *s)

 static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
 {
-    static DirtyBitmapLoadState s;
+    static DBMLoadState s;
     int ret = 0;

     trace_dirty_bitmap_load_enter();
@@ -753,7 +757,7 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)

 static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
 {
-    DirtyBitmapMigBitmapState *dbms = NULL;
+    SaveBitmapState *dbms = NULL;
     if (init_dirty_bitmap_migration() < 0) {
         return -1;
     }
-- 
2.27.0

[PULL 10/24] migration/block-dirty-bitmap: rename dirty_bitmap_mig_cleanup

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Rename dirty_bitmap_mig_cleanup to dirty_bitmap_do_save_cleanup, to
stress that it is on save part.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-10-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 1d57bff4f6c7..01a536d7d3d3 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -259,7 +259,7 @@ static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,
 }

 /* Called with iothread lock taken.  */
-static void dirty_bitmap_mig_cleanup(void)
+static void dirty_bitmap_do_save_cleanup(void)
 {
     SaveBitmapState *dbms;

@@ -406,7 +406,7 @@ static int init_dirty_bitmap_migration(void)

 fail:
     g_hash_table_destroy(handled_by_blk);
-    dirty_bitmap_mig_cleanup();
+    dirty_bitmap_do_save_cleanup();

     return -1;
 }
@@ -445,7 +445,7 @@ static void bulk_phase(QEMUFile *f, bool limit)
 /* for SaveVMHandlers */
 static void dirty_bitmap_save_cleanup(void *opaque)
 {
-    dirty_bitmap_mig_cleanup();
+    dirty_bitmap_do_save_cleanup();
 }

 static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
@@ -480,7 +480,7 @@ static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)

     trace_dirty_bitmap_save_complete_finish();

-    dirty_bitmap_mig_cleanup();
+    dirty_bitmap_do_save_cleanup();
     return 0;
 }

-- 
2.27.0

[PULL 11/24] migration/block-dirty-bitmap: move mutex init to dirty_bitmap_mig_init

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

No reasons to keep two public init functions.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20200727194236.19551-11-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/migration.h          | 1 -
 migration/block-dirty-bitmap.c | 6 +-----
 migration/migration.c          | 2 --
 3 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/migration/migration.h b/migration/migration.h
index f617960522aa..ab20c756f549 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -335,7 +335,6 @@ void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis,
 void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value);

 void dirty_bitmap_mig_before_vm_start(void);
-void init_dirty_bitmap_incoming_migration(void);
 void migrate_add_address(SocketAddress *address);

 int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque);
diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 01a536d7d3d3..4b67e4f4fbcd 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -148,11 +148,6 @@ typedef struct LoadBitmapState {
 static GSList *enabled_bitmaps;
 QemuMutex finish_lock;

-void init_dirty_bitmap_incoming_migration(void)
-{
-    qemu_mutex_init(&finish_lock);
-}
-
 static uint32_t qemu_get_bitmap_flags(QEMUFile *f)
 {
     uint8_t flags = qemu_get_byte(f);
@@ -801,6 +796,7 @@ static SaveVMHandlers savevm_dirty_bitmap_handlers = {
 void dirty_bitmap_mig_init(void)
 {
     QSIMPLEQ_INIT(&dirty_bitmap_mig_state.dbms_list);
+    qemu_mutex_init(&finish_lock);

     register_savevm_live("dirty-bitmap", 0, 1,
                          &savevm_dirty_bitmap_handlers,
diff --git a/migration/migration.c b/migration/migration.c
index 2ed99232272e..1c61428988e9 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -165,8 +165,6 @@ void migration_object_init(void)
     qemu_sem_init(&current_incoming->postcopy_pause_sem_dst, 0);
     qemu_sem_init(&current_incoming->postcopy_pause_sem_fault, 0);

-    init_dirty_bitmap_incoming_migration();
-
     if (!migration_object_check(current_migration, &err)) {
         error_report_err(err);
         exit(1);
-- 
2.27.0

[PULL 12/24] migration/block-dirty-bitmap: refactor state global variables

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Move all state variables into one global struct. Reduce global
variable usage, utilizing opaque pointer where possible.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-12-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 179 ++++++++++++++++++---------------
 1 file changed, 99 insertions(+), 80 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 4b67e4f4fbcd..9b39e7aa2b4f 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -128,6 +128,12 @@ typedef struct DBMSaveState {
     BdrvDirtyBitmap *prev_bitmap;
 } DBMSaveState;

+typedef struct LoadBitmapState {
+    BlockDriverState *bs;
+    BdrvDirtyBitmap *bitmap;
+    bool migrated;
+} LoadBitmapState;
+
 /* State of the dirty bitmap migration (DBM) during load process */
 typedef struct DBMLoadState {
     uint32_t flags;
@@ -135,18 +141,17 @@ typedef struct DBMLoadState {
     char bitmap_name[256];
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
+
+    GSList *enabled_bitmaps;
+    QemuMutex finish_lock;
 } DBMLoadState;

-static DBMSaveState dirty_bitmap_mig_state;
+typedef struct DBMState {
+    DBMSaveState save;
+    DBMLoadState load;
+} DBMState;

-/* State of one bitmap during load process */
-typedef struct LoadBitmapState {
-    BlockDriverState *bs;
-    BdrvDirtyBitmap *bitmap;
-    bool migrated;
-} LoadBitmapState;
-static GSList *enabled_bitmaps;
-QemuMutex finish_lock;
+static DBMState dbm_state;

 static uint32_t qemu_get_bitmap_flags(QEMUFile *f)
 {
@@ -169,21 +174,21 @@ static void qemu_put_bitmap_flags(QEMUFile *f, uint32_t flags)
     qemu_put_byte(f, flags);
 }

-static void send_bitmap_header(QEMUFile *f, SaveBitmapState *dbms,
-                               uint32_t additional_flags)
+static void send_bitmap_header(QEMUFile *f, DBMSaveState *s,
+                               SaveBitmapState *dbms, uint32_t additional_flags)
 {
     BlockDriverState *bs = dbms->bs;
     BdrvDirtyBitmap *bitmap = dbms->bitmap;
     uint32_t flags = additional_flags;
     trace_send_bitmap_header_enter();

-    if (bs != dirty_bitmap_mig_state.prev_bs) {
-        dirty_bitmap_mig_state.prev_bs = bs;
+    if (bs != s->prev_bs) {
+        s->prev_bs = bs;
         flags |= DIRTY_BITMAP_MIG_FLAG_DEVICE_NAME;
     }

-    if (bitmap != dirty_bitmap_mig_state.prev_bitmap) {
-        dirty_bitmap_mig_state.prev_bitmap = bitmap;
+    if (bitmap != s->prev_bitmap) {
+        s->prev_bitmap = bitmap;
         flags |= DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME;
     }

@@ -198,19 +203,22 @@ static void send_bitmap_header(QEMUFile *f, SaveBitmapState *dbms,
     }
 }

-static void send_bitmap_start(QEMUFile *f, SaveBitmapState *dbms)
+static void send_bitmap_start(QEMUFile *f, DBMSaveState *s,
+                              SaveBitmapState *dbms)
 {
-    send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_START);
+    send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_START);
     qemu_put_be32(f, bdrv_dirty_bitmap_granularity(dbms->bitmap));
     qemu_put_byte(f, dbms->flags);
 }

-static void send_bitmap_complete(QEMUFile *f, SaveBitmapState *dbms)
+static void send_bitmap_complete(QEMUFile *f, DBMSaveState *s,
+                                 SaveBitmapState *dbms)
 {
-    send_bitmap_header(f, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
+    send_bitmap_header(f, s, dbms, DIRTY_BITMAP_MIG_FLAG_COMPLETE);
 }

-static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,
+static void send_bitmap_bits(QEMUFile *f, DBMSaveState *s,
+                             SaveBitmapState *dbms,
                              uint64_t start_sector, uint32_t nr_sectors)
 {
     /* align for buffer_is_zero() */
@@ -235,7 +243,7 @@ static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,

     trace_send_bitmap_bits(flags, start_sector, nr_sectors, buf_size);

-    send_bitmap_header(f, dbms, flags);
+    send_bitmap_header(f, s, dbms, flags);

     qemu_put_be64(f, start_sector);
     qemu_put_be32(f, nr_sectors);
@@ -254,12 +262,12 @@ static void send_bitmap_bits(QEMUFile *f, SaveBitmapState *dbms,
 }

 /* Called with iothread lock taken.  */
-static void dirty_bitmap_do_save_cleanup(void)
+static void dirty_bitmap_do_save_cleanup(DBMSaveState *s)
 {
     SaveBitmapState *dbms;

-    while ((dbms = QSIMPLEQ_FIRST(&dirty_bitmap_mig_state.dbms_list)) != NULL) {
-        QSIMPLEQ_REMOVE_HEAD(&dirty_bitmap_mig_state.dbms_list, entry);
+    while ((dbms = QSIMPLEQ_FIRST(&s->dbms_list)) != NULL) {
+        QSIMPLEQ_REMOVE_HEAD(&s->dbms_list, entry);
         bdrv_dirty_bitmap_set_busy(dbms->bitmap, false);
         bdrv_unref(dbms->bs);
         g_free(dbms);
@@ -267,7 +275,8 @@ static void dirty_bitmap_do_save_cleanup(void)
 }

 /* Called with iothread lock taken. */
-static int add_bitmaps_to_list(BlockDriverState *bs, const char *bs_name)
+static int add_bitmaps_to_list(DBMSaveState *s, BlockDriverState *bs,
+                               const char *bs_name)
 {
     BdrvDirtyBitmap *bitmap;
     SaveBitmapState *dbms;
@@ -322,25 +331,24 @@ static int add_bitmaps_to_list(BlockDriverState *bs, const char *bs_name)
             dbms->flags |= DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT;
         }

-        QSIMPLEQ_INSERT_TAIL(&dirty_bitmap_mig_state.dbms_list,
-                             dbms, entry);
+        QSIMPLEQ_INSERT_TAIL(&s->dbms_list, dbms, entry);
     }

     return 0;
 }

 /* Called with iothread lock taken. */
-static int init_dirty_bitmap_migration(void)
+static int init_dirty_bitmap_migration(DBMSaveState *s)
 {
     BlockDriverState *bs;
     SaveBitmapState *dbms;
     GHashTable *handled_by_blk = g_hash_table_new(NULL, NULL);
     BlockBackend *blk;

-    dirty_bitmap_mig_state.bulk_completed = false;
-    dirty_bitmap_mig_state.prev_bs = NULL;
-    dirty_bitmap_mig_state.prev_bitmap = NULL;
-    dirty_bitmap_mig_state.no_bitmaps = false;
+    s->bulk_completed = false;
+    s->prev_bs = NULL;
+    s->prev_bitmap = NULL;
+    s->no_bitmaps = false;

     /*
      * Use blockdevice name for direct (or filtered) children of named block
@@ -369,7 +377,7 @@ static int init_dirty_bitmap_migration(void)
         }

         if (bs && bs->drv && !bs->drv->is_filter) {
-            if (add_bitmaps_to_list(bs, name)) {
+            if (add_bitmaps_to_list(s, bs, name)) {
                 goto fail;
             }
             g_hash_table_add(handled_by_blk, bs);
@@ -381,18 +389,18 @@ static int init_dirty_bitmap_migration(void)
             continue;
         }

-        if (add_bitmaps_to_list(bs, bdrv_get_node_name(bs))) {
+        if (add_bitmaps_to_list(s, bs, bdrv_get_node_name(bs))) {
             goto fail;
         }
     }

     /* unset migration flags here, to not roll back it */
-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
         bdrv_dirty_bitmap_skip_store(dbms->bitmap, true);
     }

-    if (QSIMPLEQ_EMPTY(&dirty_bitmap_mig_state.dbms_list)) {
-        dirty_bitmap_mig_state.no_bitmaps = true;
+    if (QSIMPLEQ_EMPTY(&s->dbms_list)) {
+        s->no_bitmaps = true;
     }

     g_hash_table_destroy(handled_by_blk);
@@ -401,18 +409,19 @@ static int init_dirty_bitmap_migration(void)

 fail:
     g_hash_table_destroy(handled_by_blk);
-    dirty_bitmap_do_save_cleanup();
+    dirty_bitmap_do_save_cleanup(s);

     return -1;
 }

 /* Called with no lock taken.  */
-static void bulk_phase_send_chunk(QEMUFile *f, SaveBitmapState *dbms)
+static void bulk_phase_send_chunk(QEMUFile *f, DBMSaveState *s,
+                                  SaveBitmapState *dbms)
 {
     uint32_t nr_sectors = MIN(dbms->total_sectors - dbms->cur_sector,
                              dbms->sectors_per_chunk);

-    send_bitmap_bits(f, dbms, dbms->cur_sector, nr_sectors);
+    send_bitmap_bits(f, s, dbms, dbms->cur_sector, nr_sectors);

     dbms->cur_sector += nr_sectors;
     if (dbms->cur_sector >= dbms->total_sectors) {
@@ -421,61 +430,66 @@ static void bulk_phase_send_chunk(QEMUFile *f, SaveBitmapState *dbms)
 }

 /* Called with no lock taken.  */
-static void bulk_phase(QEMUFile *f, bool limit)
+static void bulk_phase(QEMUFile *f, DBMSaveState *s, bool limit)
 {
     SaveBitmapState *dbms;

-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
         while (!dbms->bulk_completed) {
-            bulk_phase_send_chunk(f, dbms);
+            bulk_phase_send_chunk(f, s, dbms);
             if (limit && qemu_file_rate_limit(f)) {
                 return;
             }
         }
     }

-    dirty_bitmap_mig_state.bulk_completed = true;
+    s->bulk_completed = true;
 }

 /* for SaveVMHandlers */
 static void dirty_bitmap_save_cleanup(void *opaque)
 {
-    dirty_bitmap_do_save_cleanup();
+    DBMSaveState *s = &((DBMState *)opaque)->save;
+
+    dirty_bitmap_do_save_cleanup(s);
 }

 static int dirty_bitmap_save_iterate(QEMUFile *f, void *opaque)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
+
     trace_dirty_bitmap_save_iterate(migration_in_postcopy());

-    if (migration_in_postcopy() && !dirty_bitmap_mig_state.bulk_completed) {
-        bulk_phase(f, true);
+    if (migration_in_postcopy() && !s->bulk_completed) {
+        bulk_phase(f, s, true);
     }

     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);

-    return dirty_bitmap_mig_state.bulk_completed;
+    return s->bulk_completed;
 }

 /* Called with iothread lock taken.  */

 static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
     SaveBitmapState *dbms;
     trace_dirty_bitmap_save_complete_enter();

-    if (!dirty_bitmap_mig_state.bulk_completed) {
-        bulk_phase(f, false);
+    if (!s->bulk_completed) {
+        bulk_phase(f, s, false);
     }

-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
-        send_bitmap_complete(f, dbms);
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
+        send_bitmap_complete(f, s, dbms);
     }

     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);

     trace_dirty_bitmap_save_complete_finish();

-    dirty_bitmap_do_save_cleanup();
+    dirty_bitmap_save_cleanup(opaque);
     return 0;
 }

@@ -485,12 +499,13 @@ static void dirty_bitmap_save_pending(QEMUFile *f, void *opaque,
                                       uint64_t *res_compatible,
                                       uint64_t *res_postcopy_only)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
     SaveBitmapState *dbms;
     uint64_t pending = 0;

     qemu_mutex_lock_iothread();

-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
         uint64_t gran = bdrv_dirty_bitmap_granularity(dbms->bitmap);
         uint64_t sectors = dbms->bulk_completed ? 0 :
                            dbms->total_sectors - dbms->cur_sector;
@@ -549,7 +564,7 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
         b->bs = s->bs;
         b->bitmap = s->bitmap;
         b->migrated = false;
-        enabled_bitmaps = g_slist_prepend(enabled_bitmaps, b);
+        s->enabled_bitmaps = g_slist_prepend(s->enabled_bitmaps, b);
     }

     return 0;
@@ -557,11 +572,12 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)

 void dirty_bitmap_mig_before_vm_start(void)
 {
+    DBMLoadState *s = &dbm_state.load;
     GSList *item;

-    qemu_mutex_lock(&finish_lock);
+    qemu_mutex_lock(&s->finish_lock);

-    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+    for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;

         if (b->migrated) {
@@ -573,10 +589,10 @@ void dirty_bitmap_mig_before_vm_start(void)
         g_free(b);
     }

-    g_slist_free(enabled_bitmaps);
-    enabled_bitmaps = NULL;
+    g_slist_free(s->enabled_bitmaps);
+    s->enabled_bitmaps = NULL;

-    qemu_mutex_unlock(&finish_lock);
+    qemu_mutex_unlock(&s->finish_lock);
 }

 static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
@@ -585,9 +601,9 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
     trace_dirty_bitmap_load_complete();
     bdrv_dirty_bitmap_deserialize_finish(s->bitmap);

-    qemu_mutex_lock(&finish_lock);
+    qemu_mutex_lock(&s->finish_lock);

-    for (item = enabled_bitmaps; item; item = g_slist_next(item)) {
+    for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;

         if (b->bitmap == s->bitmap) {
@@ -598,7 +614,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)

     if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
         bdrv_dirty_bitmap_lock(s->bitmap);
-        if (enabled_bitmaps == NULL) {
+        if (s->enabled_bitmaps == NULL) {
             /* in postcopy */
             bdrv_reclaim_dirty_bitmap_locked(s->bitmap, &error_abort);
             bdrv_enable_dirty_bitmap_locked(s->bitmap);
@@ -617,7 +633,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
         bdrv_dirty_bitmap_unlock(s->bitmap);
     }

-    qemu_mutex_unlock(&finish_lock);
+    qemu_mutex_unlock(&s->finish_lock);
 }

 static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
@@ -714,7 +730,7 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s)

 static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
 {
-    static DBMLoadState s;
+    DBMLoadState *s = &((DBMState *)opaque)->load;
     int ret = 0;

     trace_dirty_bitmap_load_enter();
@@ -724,17 +740,17 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
     }

     do {
-        ret = dirty_bitmap_load_header(f, &s);
+        ret = dirty_bitmap_load_header(f, s);
         if (ret < 0) {
             return ret;
         }

-        if (s.flags & DIRTY_BITMAP_MIG_FLAG_START) {
-            ret = dirty_bitmap_load_start(f, &s);
-        } else if (s.flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
-            dirty_bitmap_load_complete(f, &s);
-        } else if (s.flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
-            ret = dirty_bitmap_load_bits(f, &s);
+        if (s->flags & DIRTY_BITMAP_MIG_FLAG_START) {
+            ret = dirty_bitmap_load_start(f, s);
+        } else if (s->flags & DIRTY_BITMAP_MIG_FLAG_COMPLETE) {
+            dirty_bitmap_load_complete(f, s);
+        } else if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITS) {
+            ret = dirty_bitmap_load_bits(f, s);
         }

         if (!ret) {
@@ -744,7 +760,7 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
         if (ret) {
             return ret;
         }
-    } while (!(s.flags & DIRTY_BITMAP_MIG_FLAG_EOS));
+    } while (!(s->flags & DIRTY_BITMAP_MIG_FLAG_EOS));

     trace_dirty_bitmap_load_success();
     return 0;
@@ -752,13 +768,14 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)

 static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)
 {
+    DBMSaveState *s = &((DBMState *)opaque)->save;
     SaveBitmapState *dbms = NULL;
-    if (init_dirty_bitmap_migration() < 0) {
+    if (init_dirty_bitmap_migration(s) < 0) {
         return -1;
     }

-    QSIMPLEQ_FOREACH(dbms, &dirty_bitmap_mig_state.dbms_list, entry) {
-        send_bitmap_start(f, dbms);
+    QSIMPLEQ_FOREACH(dbms, &s->dbms_list, entry) {
+        send_bitmap_start(f, s, dbms);
     }
     qemu_put_bitmap_flags(f, DIRTY_BITMAP_MIG_FLAG_EOS);

@@ -767,7 +784,9 @@ static int dirty_bitmap_save_setup(QEMUFile *f, void *opaque)

 static bool dirty_bitmap_is_active(void *opaque)
 {
-    return migrate_dirty_bitmaps() && !dirty_bitmap_mig_state.no_bitmaps;
+    DBMSaveState *s = &((DBMState *)opaque)->save;
+
+    return migrate_dirty_bitmaps() && !s->no_bitmaps;
 }

 static bool dirty_bitmap_is_active_iterate(void *opaque)
@@ -795,10 +814,10 @@ static SaveVMHandlers savevm_dirty_bitmap_handlers = {

 void dirty_bitmap_mig_init(void)
 {
-    QSIMPLEQ_INIT(&dirty_bitmap_mig_state.dbms_list);
-    qemu_mutex_init(&finish_lock);
+    QSIMPLEQ_INIT(&dbm_state.save.dbms_list);
+    qemu_mutex_init(&dbm_state.load.finish_lock);

     register_savevm_live("dirty-bitmap", 0, 1,
                          &savevm_dirty_bitmap_handlers,
-                         &dirty_bitmap_mig_state);
+                         &dbm_state);
 }
-- 
2.27.0

[PULL 13/24] migration/block-dirty-bitmap: rename finish_lock to just lock

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

finish_lock is bad name, as lock used not only on process end.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-13-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 9b39e7aa2b4f..9194807b54f1 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -143,7 +143,7 @@ typedef struct DBMLoadState {
     BdrvDirtyBitmap *bitmap;

     GSList *enabled_bitmaps;
-    QemuMutex finish_lock;
+    QemuMutex lock; /* protect enabled_bitmaps */
 } DBMLoadState;

 typedef struct DBMState {
@@ -575,7 +575,7 @@ void dirty_bitmap_mig_before_vm_start(void)
     DBMLoadState *s = &dbm_state.load;
     GSList *item;

-    qemu_mutex_lock(&s->finish_lock);
+    qemu_mutex_lock(&s->lock);

     for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;
@@ -592,7 +592,7 @@ void dirty_bitmap_mig_before_vm_start(void)
     g_slist_free(s->enabled_bitmaps);
     s->enabled_bitmaps = NULL;

-    qemu_mutex_unlock(&s->finish_lock);
+    qemu_mutex_unlock(&s->lock);
 }

 static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
@@ -601,7 +601,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
     trace_dirty_bitmap_load_complete();
     bdrv_dirty_bitmap_deserialize_finish(s->bitmap);

-    qemu_mutex_lock(&s->finish_lock);
+    qemu_mutex_lock(&s->lock);

     for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;
@@ -633,7 +633,7 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
         bdrv_dirty_bitmap_unlock(s->bitmap);
     }

-    qemu_mutex_unlock(&s->finish_lock);
+    qemu_mutex_unlock(&s->lock);
 }

 static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
@@ -815,7 +815,7 @@ static SaveVMHandlers savevm_dirty_bitmap_handlers = {
 void dirty_bitmap_mig_init(void)
 {
     QSIMPLEQ_INIT(&dbm_state.save.dbms_list);
-    qemu_mutex_init(&dbm_state.load.finish_lock);
+    qemu_mutex_init(&dbm_state.load.lock);

     register_savevm_live("dirty-bitmap", 0, 1,
                          &savevm_dirty_bitmap_handlers,
-- 
2.27.0

[PULL 14/24] migration/block-dirty-bitmap: simplify dirty_bitmap_load_complete

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

bdrv_enable_dirty_bitmap_locked() call does nothing, as if we are in
postcopy, bitmap successor must be enabled, and reclaim operation will
enable the bitmap.

So, actually we need just call _reclaim_ in both if branches, and
making differences only to add an assertion seems not really good. The
logic becomes simple: on load complete we do reclaim and that's all.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-14-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 9194807b54f1..405a259296d9 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -603,6 +603,10 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)

     qemu_mutex_lock(&s->lock);

+    if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
+        bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
+    }
+
     for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;

@@ -612,27 +616,6 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
         }
     }

-    if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
-        bdrv_dirty_bitmap_lock(s->bitmap);
-        if (s->enabled_bitmaps == NULL) {
-            /* in postcopy */
-            bdrv_reclaim_dirty_bitmap_locked(s->bitmap, &error_abort);
-            bdrv_enable_dirty_bitmap_locked(s->bitmap);
-        } else {
-            /* target not started, successor must be empty */
-            int64_t count = bdrv_get_dirty_count(s->bitmap);
-            BdrvDirtyBitmap *ret = bdrv_reclaim_dirty_bitmap_locked(s->bitmap,
-                                                                    NULL);
-            /* bdrv_reclaim_dirty_bitmap can fail only on no successor (it
-             * must be) or on merge fail, but merge can't fail when second
-             * bitmap is empty
-             */
-            assert(ret == s->bitmap &&
-                   count == bdrv_get_dirty_count(s->bitmap));
-        }
-        bdrv_dirty_bitmap_unlock(s->bitmap);
-    }
-
     qemu_mutex_unlock(&s->lock);
 }

-- 
2.27.0

[PULL 15/24] migration/block-dirty-bitmap: keep bitmap state for all bitmaps

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Keep bitmap state for disabled bitmaps too. Keep the state until the
end of the process. It's needed for the following commit to implement
bitmap postcopy canceling.

To clean-up the new list the following logic is used:
We need two events to consider bitmap migration finished:
1. chunk with DIRTY_BITMAP_MIG_FLAG_COMPLETE flag should be received
2. dirty_bitmap_mig_before_vm_start should be called
These two events may come in any order, so we understand which one is
last, and on the last of them we remove bitmap migration state from the
list.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-15-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 64 +++++++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 21 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 405a259296d9..eb4ffeac4d1b 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -132,6 +132,7 @@ typedef struct LoadBitmapState {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;
     bool migrated;
+    bool enabled;
 } LoadBitmapState;

 /* State of the dirty bitmap migration (DBM) during load process */
@@ -142,8 +143,10 @@ typedef struct DBMLoadState {
     BlockDriverState *bs;
     BdrvDirtyBitmap *bitmap;

-    GSList *enabled_bitmaps;
-    QemuMutex lock; /* protect enabled_bitmaps */
+    bool before_vm_start_handled; /* set in dirty_bitmap_mig_before_vm_start */
+
+    GSList *bitmaps;
+    QemuMutex lock; /* protect bitmaps */
 } DBMLoadState;

 typedef struct DBMState {
@@ -526,6 +529,7 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
     Error *local_err = NULL;
     uint32_t granularity = qemu_get_be32(f);
     uint8_t flags = qemu_get_byte(f);
+    LoadBitmapState *b;

     if (s->bitmap) {
         error_report("Bitmap with the same name ('%s') already exists on "
@@ -552,45 +556,59 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)

     bdrv_disable_dirty_bitmap(s->bitmap);
     if (flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED) {
-        LoadBitmapState *b;
-
         bdrv_dirty_bitmap_create_successor(s->bitmap, &local_err);
         if (local_err) {
             error_report_err(local_err);
             return -EINVAL;
         }
-
-        b = g_new(LoadBitmapState, 1);
-        b->bs = s->bs;
-        b->bitmap = s->bitmap;
-        b->migrated = false;
-        s->enabled_bitmaps = g_slist_prepend(s->enabled_bitmaps, b);
     }

+    b = g_new(LoadBitmapState, 1);
+    b->bs = s->bs;
+    b->bitmap = s->bitmap;
+    b->migrated = false;
+    b->enabled = flags & DIRTY_BITMAP_MIG_START_FLAG_ENABLED;
+
+    s->bitmaps = g_slist_prepend(s->bitmaps, b);
+
     return 0;
 }

-void dirty_bitmap_mig_before_vm_start(void)
+/*
+ * before_vm_start_handle_item
+ *
+ * g_slist_foreach helper
+ *
+ * item is LoadBitmapState*
+ * opaque is DBMLoadState*
+ */
+static void before_vm_start_handle_item(void *item, void *opaque)
 {
-    DBMLoadState *s = &dbm_state.load;
-    GSList *item;
-
-    qemu_mutex_lock(&s->lock);
-
-    for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
-        LoadBitmapState *b = item->data;
+    DBMLoadState *s = opaque;
+    LoadBitmapState *b = item;

+    if (b->enabled) {
         if (b->migrated) {
             bdrv_enable_dirty_bitmap(b->bitmap);
         } else {
             bdrv_dirty_bitmap_enable_successor(b->bitmap);
         }
+    }

+    if (b->migrated) {
+        s->bitmaps = g_slist_remove(s->bitmaps, b);
         g_free(b);
     }
+}

-    g_slist_free(s->enabled_bitmaps);
-    s->enabled_bitmaps = NULL;
+void dirty_bitmap_mig_before_vm_start(void)
+{
+    DBMLoadState *s = &dbm_state.load;
+    qemu_mutex_lock(&s->lock);
+
+    assert(!s->before_vm_start_handled);
+    g_slist_foreach(s->bitmaps, before_vm_start_handle_item, s);
+    s->before_vm_start_handled = true;

     qemu_mutex_unlock(&s->lock);
 }
@@ -607,11 +625,15 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
         bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
     }

-    for (item = s->enabled_bitmaps; item; item = g_slist_next(item)) {
+    for (item = s->bitmaps; item; item = g_slist_next(item)) {
         LoadBitmapState *b = item->data;

         if (b->bitmap == s->bitmap) {
             b->migrated = true;
+            if (s->before_vm_start_handled) {
+                s->bitmaps = g_slist_remove(s->bitmaps, b);
+                g_free(b);
+            }
             break;
         }
     }
-- 
2.27.0

[PULL 16/24] migration/block-dirty-bitmap: relax error handling in incoming part

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Bitmaps data is not critical, and we should not fail the migration (or
use postcopy recovering) because of dirty-bitmaps migration failure.
Instead we should just lose unfinished bitmaps.

Still we have to report io stream violation errors, as they affect the
whole migration stream.

While touching this, tighten code that was previously blindly calling
malloc on a size read from the migration stream, as a corrupted stream
(perhaps from a malicious user) should not be able to convince us to
allocate an inordinate amount of memory.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200727194236.19551-16-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: typo fixes, enhance commit message]
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 162 +++++++++++++++++++++++++--------
 1 file changed, 126 insertions(+), 36 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index eb4ffeac4d1b..f91015a4f88f 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -145,6 +145,15 @@ typedef struct DBMLoadState {

     bool before_vm_start_handled; /* set in dirty_bitmap_mig_before_vm_start */

+    /*
+     * cancelled
+     * Incoming migration is cancelled for some reason. That means that we
+     * still should read our chunks from migration stream, to not affect other
+     * migration objects (like RAM), but just ignore them and do not touch any
+     * bitmaps or nodes.
+     */
+    bool cancelled;
+
     GSList *bitmaps;
     QemuMutex lock; /* protect bitmaps */
 } DBMLoadState;
@@ -531,6 +540,10 @@ static int dirty_bitmap_load_start(QEMUFile *f, DBMLoadState *s)
     uint8_t flags = qemu_get_byte(f);
     LoadBitmapState *b;

+    if (s->cancelled) {
+        return 0;
+    }
+
     if (s->bitmap) {
         error_report("Bitmap with the same name ('%s') already exists on "
                      "destination", bdrv_dirty_bitmap_name(s->bitmap));
@@ -613,14 +626,48 @@ void dirty_bitmap_mig_before_vm_start(void)
     qemu_mutex_unlock(&s->lock);
 }

+static void cancel_incoming_locked(DBMLoadState *s)
+{
+    GSList *item;
+
+    if (s->cancelled) {
+        return;
+    }
+
+    s->cancelled = true;
+    s->bs = NULL;
+    s->bitmap = NULL;
+
+    /* Drop all unfinished bitmaps */
+    for (item = s->bitmaps; item; item = g_slist_next(item)) {
+        LoadBitmapState *b = item->data;
+
+        /*
+         * Bitmap must be unfinished, as finished bitmaps should already be
+         * removed from the list.
+         */
+        assert(!s->before_vm_start_handled || !b->migrated);
+        if (bdrv_dirty_bitmap_has_successor(b->bitmap)) {
+            bdrv_reclaim_dirty_bitmap(b->bitmap, &error_abort);
+        }
+        bdrv_release_dirty_bitmap(b->bitmap);
+    }
+
+    g_slist_free_full(s->bitmaps, g_free);
+    s->bitmaps = NULL;
+}
+
 static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
 {
     GSList *item;
     trace_dirty_bitmap_load_complete();
+
+    if (s->cancelled) {
+        return;
+    }
+
     bdrv_dirty_bitmap_deserialize_finish(s->bitmap);

-    qemu_mutex_lock(&s->lock);
-
     if (bdrv_dirty_bitmap_has_successor(s->bitmap)) {
         bdrv_reclaim_dirty_bitmap(s->bitmap, &error_abort);
     }
@@ -637,8 +684,6 @@ static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
             break;
         }
     }
-
-    qemu_mutex_unlock(&s->lock);
 }

 static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
@@ -650,15 +695,46 @@ static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)

     if (s->flags & DIRTY_BITMAP_MIG_FLAG_ZEROES) {
         trace_dirty_bitmap_load_bits_zeroes();
-        bdrv_dirty_bitmap_deserialize_zeroes(s->bitmap, first_byte, nr_bytes,
-                                             false);
+        if (!s->cancelled) {
+            bdrv_dirty_bitmap_deserialize_zeroes(s->bitmap, first_byte,
+                                                 nr_bytes, false);
+        }
     } else {
         size_t ret;
-        uint8_t *buf;
+        g_autofree uint8_t *buf = NULL;
         uint64_t buf_size = qemu_get_be64(f);
-        uint64_t needed_size =
-            bdrv_dirty_bitmap_serialization_size(s->bitmap,
-                                                 first_byte, nr_bytes);
+        uint64_t needed_size;
+
+        /*
+         * The actual check for buf_size is done a bit later. We can't do it in
+         * cancelled mode as we don't have the bitmap to check the constraints
+         * (so, we allocate a buffer and read prior to the check). On the other
+         * hand, we shouldn't blindly g_malloc the number from the stream.
+         * Actually one chunk should not be larger than CHUNK_SIZE. Let's allow
+         * a bit larger (which means that bitmap migration will fail anyway and
+         * the whole migration will most probably fail soon due to broken
+         * stream).
+         */
+        if (buf_size > 10 * CHUNK_SIZE) {
+            error_report("Bitmap migration stream buffer allocation request "
+                         "is too large");
+            return -EIO;
+        }
+
+        buf = g_malloc(buf_size);
+        ret = qemu_get_buffer(f, buf, buf_size);
+        if (ret != buf_size) {
+            error_report("Failed to read bitmap bits");
+            return -EIO;
+        }
+
+        if (s->cancelled) {
+            return 0;
+        }
+
+        needed_size = bdrv_dirty_bitmap_serialization_size(s->bitmap,
+                                                           first_byte,
+                                                           nr_bytes);

         if (needed_size > buf_size ||
             buf_size > QEMU_ALIGN_UP(needed_size, 4 * sizeof(long))
@@ -667,20 +743,12 @@ static int dirty_bitmap_load_bits(QEMUFile *f, DBMLoadState *s)
             error_report("Migrated bitmap granularity doesn't "
                          "match the destination bitmap '%s' granularity",
                          bdrv_dirty_bitmap_name(s->bitmap));
-            return -EINVAL;
-        }
-
-        buf = g_malloc(buf_size);
-        ret = qemu_get_buffer(f, buf, buf_size);
-        if (ret != buf_size) {
-            error_report("Failed to read bitmap bits");
-            g_free(buf);
-            return -EIO;
+            cancel_incoming_locked(s);
+            return 0;
         }

         bdrv_dirty_bitmap_deserialize_part(s->bitmap, buf, first_byte, nr_bytes,
                                            false);
-        g_free(buf);
     }

     return 0;
@@ -700,14 +768,16 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s)
             error_report("Unable to read node name string");
             return -EINVAL;
         }
-        s->bs = bdrv_lookup_bs(s->node_name, s->node_name, &local_err);
-        if (!s->bs) {
-            error_report_err(local_err);
-            return -EINVAL;
+        if (!s->cancelled) {
+            s->bs = bdrv_lookup_bs(s->node_name, s->node_name, &local_err);
+            if (!s->bs) {
+                error_report_err(local_err);
+                cancel_incoming_locked(s);
+            }
         }
-    } else if (!s->bs && !nothing) {
+    } else if (!s->bs && !nothing && !s->cancelled) {
         error_report("Error: block device name is not set");
-        return -EINVAL;
+        cancel_incoming_locked(s);
     }

     if (s->flags & DIRTY_BITMAP_MIG_FLAG_BITMAP_NAME) {
@@ -715,24 +785,38 @@ static int dirty_bitmap_load_header(QEMUFile *f, DBMLoadState *s)
             error_report("Unable to read bitmap name string");
             return -EINVAL;
         }
-        s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);
+        if (!s->cancelled) {
+            s->bitmap = bdrv_find_dirty_bitmap(s->bs, s->bitmap_name);

-        /* bitmap may be NULL here, it wouldn't be an error if it is the
-         * first occurrence of the bitmap */
-        if (!s->bitmap && !(s->flags & DIRTY_BITMAP_MIG_FLAG_START)) {
-            error_report("Error: unknown dirty bitmap "
-                         "'%s' for block device '%s'",
-                         s->bitmap_name, s->node_name);
-            return -EINVAL;
+            /*
+             * bitmap may be NULL here, it wouldn't be an error if it is the
+             * first occurrence of the bitmap
+             */
+            if (!s->bitmap && !(s->flags & DIRTY_BITMAP_MIG_FLAG_START)) {
+                error_report("Error: unknown dirty bitmap "
+                             "'%s' for block device '%s'",
+                             s->bitmap_name, s->node_name);
+                cancel_incoming_locked(s);
+            }
         }
-    } else if (!s->bitmap && !nothing) {
+    } else if (!s->bitmap && !nothing && !s->cancelled) {
         error_report("Error: block device name is not set");
-        return -EINVAL;
+        cancel_incoming_locked(s);
     }

     return 0;
 }

+/*
+ * dirty_bitmap_load
+ *
+ * Load sequence of dirty bitmap chunks. Return error only on fatal io stream
+ * violations. On other errors just cancel bitmaps incoming migration and return
+ * 0.
+ *
+ * Note, than when incoming bitmap migration is canceled, we still must read all
+ * our chunks (and just ignore them), to not affect other migration objects.
+ */
 static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
 {
     DBMLoadState *s = &((DBMState *)opaque)->load;
@@ -741,12 +825,17 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
     trace_dirty_bitmap_load_enter();

     if (version_id != 1) {
+        QEMU_LOCK_GUARD(&s->lock);
+        cancel_incoming_locked(s);
         return -EINVAL;
     }

     do {
+        QEMU_LOCK_GUARD(&s->lock);
+
         ret = dirty_bitmap_load_header(f, s);
         if (ret < 0) {
+            cancel_incoming_locked(s);
             return ret;
         }

@@ -763,6 +852,7 @@ static int dirty_bitmap_load(QEMUFile *f, void *opaque, int version_id)
         }

         if (ret) {
+            cancel_incoming_locked(s);
             return ret;
         }
     } while (!(s->flags & DIRTY_BITMAP_MIG_FLAG_EOS));
-- 
2.27.0

[PULL 17/24] migration/block-dirty-bitmap: cancel migration on shutdown

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

If target is turned off prior to postcopy finished, target crashes
because busy bitmaps are found at shutdown.
Canceling incoming migration helps, as it removes all unfinished (and
therefore busy) bitmaps.

Similarly on source we crash in bdrv_close_all which asserts that all
bdrv states are removed, because bdrv states involved into dirty bitmap
migration are referenced by it. So, we need to cancel outgoing
migration as well.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-17-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/migration.h          |  2 ++
 migration/block-dirty-bitmap.c | 16 ++++++++++++++++
 migration/migration.c          | 13 +++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/migration/migration.h b/migration/migration.h
index ab20c756f549..6c6a931d0dc2 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -335,6 +335,8 @@ void migrate_send_rp_recv_bitmap(MigrationIncomingState *mis,
 void migrate_send_rp_resume_ack(MigrationIncomingState *mis, uint32_t value);

 void dirty_bitmap_mig_before_vm_start(void);
+void dirty_bitmap_mig_cancel_outgoing(void);
+void dirty_bitmap_mig_cancel_incoming(void);
 void migrate_add_address(SocketAddress *address);

 int foreach_not_ignored_block(RAMBlockIterFunc func, void *opaque);
diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index f91015a4f88f..1f675b792fc9 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -657,6 +657,22 @@ static void cancel_incoming_locked(DBMLoadState *s)
     s->bitmaps = NULL;
 }

+void dirty_bitmap_mig_cancel_outgoing(void)
+{
+    dirty_bitmap_do_save_cleanup(&dbm_state.save);
+}
+
+void dirty_bitmap_mig_cancel_incoming(void)
+{
+    DBMLoadState *s = &dbm_state.load;
+
+    qemu_mutex_lock(&s->lock);
+
+    cancel_incoming_locked(s);
+
+    qemu_mutex_unlock(&s->lock);
+}
+
 static void dirty_bitmap_load_complete(QEMUFile *f, DBMLoadState *s)
 {
     GSList *item;
diff --git a/migration/migration.c b/migration/migration.c
index 1c61428988e9..8fe36339dbe8 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -188,6 +188,19 @@ void migration_shutdown(void)
      */
     migrate_fd_cancel(current_migration);
     object_unref(OBJECT(current_migration));
+
+    /*
+     * Cancel outgoing migration of dirty bitmaps. It should
+     * at least unref used block nodes.
+     */
+    dirty_bitmap_mig_cancel_outgoing();
+
+    /*
+     * Cancel incoming migration of dirty bitmaps. Dirty bitmaps
+     * are non-critical data, and their loss never considered as
+     * something serious.
+     */
+    dirty_bitmap_mig_cancel_incoming();
 }

 /* For outgoing */
-- 
2.27.0

[PULL 18/24] migration/savevm: don't worry if bitmap migration postcopy failed

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

First, if only bitmaps postcopy is enabled (and not ram postcopy)
postcopy_pause_incoming crashes on an assertion
assert(mis->to_src_file).

And anyway, bitmaps postcopy is not prepared to be somehow recovered.
The original idea instead is that if bitmaps postcopy failed, we just
lose some bitmaps, which is not critical. So, on failure we just need
to remove unfinished bitmaps and guest should continue execution on
destination.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-18-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 migration/savevm.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index 45c9dd9d8a6d..a843d202b5b4 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1813,6 +1813,9 @@ static void *postcopy_ram_listen_thread(void *opaque)
     MigrationIncomingState *mis = migration_incoming_get_current();
     QEMUFile *f = mis->from_src_file;
     int load_res;
+    MigrationState *migr = migrate_get_current();
+
+    object_ref(OBJECT(migr));

     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                                    MIGRATION_STATUS_POSTCOPY_ACTIVE);
@@ -1839,11 +1842,24 @@ static void *postcopy_ram_listen_thread(void *opaque)

     trace_postcopy_ram_listen_thread_exit();
     if (load_res < 0) {
-        error_report("%s: loadvm failed: %d", __func__, load_res);
         qemu_file_set_error(f, load_res);
-        migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
-                                       MIGRATION_STATUS_FAILED);
-    } else {
+        dirty_bitmap_mig_cancel_incoming();
+        if (postcopy_state_get() == POSTCOPY_INCOMING_RUNNING &&
+            !migrate_postcopy_ram() && migrate_dirty_bitmaps())
+        {
+            error_report("%s: loadvm failed during postcopy: %d. All states "
+                         "are migrated except dirty bitmaps. Some dirty "
+                         "bitmaps may be lost, and present migrated dirty "
+                         "bitmaps are correctly migrated and valid.",
+                         __func__, load_res);
+            load_res = 0; /* prevent further exit() */
+        } else {
+            error_report("%s: loadvm failed: %d", __func__, load_res);
+            migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
+                                           MIGRATION_STATUS_FAILED);
+        }
+    }
+    if (load_res >= 0) {
         /*
          * This looks good, but it's possible that the device loading in the
          * main thread hasn't finished yet, and so we might not be in 'RUN'
@@ -1879,6 +1895,8 @@ static void *postcopy_ram_listen_thread(void *opaque)
     mis->have_listen_thread = false;
     postcopy_state_set(POSTCOPY_INCOMING_END);

+    object_unref(OBJECT(migr));
+
     return NULL;
 }

@@ -2437,6 +2455,8 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
 {
     trace_postcopy_pause_incoming();

+    assert(migrate_postcopy_ram());
+
     /* Clear the triggered bit to allow one recovery */
     mis->postcopy_recover_triggered = false;

@@ -2521,15 +2541,22 @@ out:
     if (ret < 0) {
         qemu_file_set_error(f, ret);

+        /* Cancel bitmaps incoming regardless of recovery */
+        dirty_bitmap_mig_cancel_incoming();
+
         /*
          * If we are during an active postcopy, then we pause instead
          * of bail out to at least keep the VM's dirty data.  Note
          * that POSTCOPY_INCOMING_LISTENING stage is still not enough,
          * during which we're still receiving device states and we
          * still haven't yet started the VM on destination.
+         *
+         * Only RAM postcopy supports recovery. Still, if RAM postcopy is
+         * enabled, canceled bitmaps postcopy will not affect RAM postcopy
+         * recovering.
          */
         if (postcopy_state_get() == POSTCOPY_INCOMING_RUNNING &&
-            postcopy_pause_incoming(mis)) {
+            migrate_postcopy_ram() && postcopy_pause_incoming(mis)) {
             /* Reset f to point to the newly created channel */
             f = mis->from_src_file;
             goto retry;
-- 
2.27.0

[PULL 19/24] qemu-iotests/199: prepare for new test-cases addition

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Move future common part to start_postcopy() method. Move checking
number of bitmaps to check_bitmap().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-19-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index d8532e49da00..355c0b288592 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -29,6 +29,8 @@ disk_b = os.path.join(iotests.test_dir, 'disk_b')
 size = '256G'
 fifo = os.path.join(iotests.test_dir, 'mig_fifo')

+granularity = 512
+nb_bitmaps = 15

 GiB = 1024 * 1024 * 1024

@@ -61,6 +63,15 @@ def event_dist(e1, e2):
     return event_seconds(e2) - event_seconds(e1)


+def check_bitmaps(vm, count):
+    result = vm.qmp('query-block')
+
+    if count == 0:
+        assert 'dirty-bitmaps' not in result['return'][0]
+    else:
+        assert len(result['return'][0]['dirty-bitmaps']) == count
+
+
 class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
     def tearDown(self):
         if debug:
@@ -101,10 +112,8 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         self.vm_a_events = []
         self.vm_b_events = []

-    def test_postcopy(self):
-        granularity = 512
-        nb_bitmaps = 15
-
+    def start_postcopy(self):
+        """ Run migration until RESUME event on target. Return this event. """
         for i in range(nb_bitmaps):
             result = self.vm_a.qmp('block-dirty-bitmap-add', node='drive0',
                                    name='bitmap{}'.format(i),
@@ -119,10 +128,10 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):

         result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
                                node='drive0', name='bitmap0')
-        discards1_sha256 = result['return']['sha256']
+        self.discards1_sha256 = result['return']['sha256']

         # Check, that updating the bitmap by discards works
-        assert discards1_sha256 != empty_sha256
+        assert self.discards1_sha256 != empty_sha256

         # We want to calculate resulting sha256. Do it in bitmap0, so, disable
         # other bitmaps
@@ -135,7 +144,7 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):

         result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
                                node='drive0', name='bitmap0')
-        all_discards_sha256 = result['return']['sha256']
+        self.all_discards_sha256 = result['return']['sha256']

         # Now, enable some bitmaps, to be updated during migration
         for i in range(2, nb_bitmaps, 2):
@@ -160,6 +169,10 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):

         event_resume = self.vm_b.event_wait('RESUME')
         self.vm_b_events.append(event_resume)
+        return event_resume
+
+    def test_postcopy_success(self):
+        event_resume = self.start_postcopy()

         # enabled bitmaps should be updated
         apply_discards(self.vm_b, discards2)
@@ -180,18 +193,15 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
             print('downtime:', downtime)
             print('postcopy_time:', postcopy_time)

-        # Assert that bitmap migration is finished (check that successor bitmap
-        # is removed)
-        result = self.vm_b.qmp('query-block')
-        assert len(result['return'][0]['dirty-bitmaps']) == nb_bitmaps
+        check_bitmaps(self.vm_b, nb_bitmaps)

         # Check content of migrated bitmaps. Still, don't waste time checking
         # every bitmap
         for i in range(0, nb_bitmaps, 5):
             result = self.vm_b.qmp('x-debug-block-dirty-bitmap-sha256',
                                    node='drive0', name='bitmap{}'.format(i))
-            sha256 = discards1_sha256 if i % 2 else all_discards_sha256
-            self.assert_qmp(result, 'return/sha256', sha256)
+            sha = self.discards1_sha256 if i % 2 else self.all_discards_sha256
+            self.assert_qmp(result, 'return/sha256', sha)


 if __name__ == '__main__':
-- 
2.27.0

[PULL 20/24] qemu-iotests/199: check persistent bitmaps

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Check that persistent bitmaps are not stored on source and that bitmaps
are persistent on destination.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200727194236.19551-20-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199 | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index 355c0b288592..5fd34f0fcdfa 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -117,7 +117,8 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         for i in range(nb_bitmaps):
             result = self.vm_a.qmp('block-dirty-bitmap-add', node='drive0',
                                    name='bitmap{}'.format(i),
-                                   granularity=granularity)
+                                   granularity=granularity,
+                                   persistent=True)
             self.assert_qmp(result, 'return', {})

         result = self.vm_a.qmp('x-debug-block-dirty-bitmap-sha256',
@@ -193,6 +194,19 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
             print('downtime:', downtime)
             print('postcopy_time:', postcopy_time)

+        # check that there are no bitmaps stored on source
+        self.vm_a_events += self.vm_a.get_qmp_events()
+        self.vm_a.shutdown()
+        self.vm_a.launch()
+        check_bitmaps(self.vm_a, 0)
+
+        # check that bitmaps are migrated and persistence works
+        check_bitmaps(self.vm_b, nb_bitmaps)
+        self.vm_b.shutdown()
+        # recreate vm_b, so there is no incoming option, which prevents
+        # loading bitmaps from disk
+        self.vm_b = iotests.VM(path_suffix='b').add_drive(disk_b)
+        self.vm_b.launch()
         check_bitmaps(self.vm_b, nb_bitmaps)

         # Check content of migrated bitmaps. Still, don't waste time checking
-- 
2.27.0

[PULL 21/24] qemu-iotests/199: add early shutdown case to bitmaps postcopy

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Previous patches fixed two crashes which may occur on shutdown prior to
bitmaps postcopy finished. Check that it works now.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-21-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199     | 24 ++++++++++++++++++++++++
 tests/qemu-iotests/199.out |  4 ++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index 5fd34f0fcdfa..140930b2b12e 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -217,6 +217,30 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
             sha = self.discards1_sha256 if i % 2 else self.all_discards_sha256
             self.assert_qmp(result, 'return/sha256', sha)

+    def test_early_shutdown_destination(self):
+        self.start_postcopy()
+
+        self.vm_b_events += self.vm_b.get_qmp_events()
+        self.vm_b.shutdown()
+        # recreate vm_b, so there is no incoming option, which prevents
+        # loading bitmaps from disk
+        self.vm_b = iotests.VM(path_suffix='b').add_drive(disk_b)
+        self.vm_b.launch()
+        check_bitmaps(self.vm_b, 0)
+
+        # Bitmaps will be lost if we just shutdown the vm, as they are marked
+        # to skip storing to disk when prepared for migration. And that's
+        # correct, as actual data may be modified in target vm, so we play
+        # safe.
+        # Still, this mark would be taken away if we do 'cont', and bitmaps
+        # become persistent again. (see iotest 169 for such behavior case)
+        result = self.vm_a.qmp('query-status')
+        assert not result['return']['running']
+        self.vm_a_events += self.vm_a.get_qmp_events()
+        self.vm_a.shutdown()
+        self.vm_a.launch()
+        check_bitmaps(self.vm_a, 0)
+

 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2'])
diff --git a/tests/qemu-iotests/199.out b/tests/qemu-iotests/199.out
index ae1213e6f863..fbc63e62f885 100644
--- a/tests/qemu-iotests/199.out
+++ b/tests/qemu-iotests/199.out
@@ -1,5 +1,5 @@
-.
+..
 ----------------------------------------------------------------------
-Ran 1 tests
+Ran 2 tests

 OK
-- 
2.27.0

[PULL 22/24] qemu-iotests/199: add source-killed case to bitmaps postcopy

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Previous patches fixes behavior of bitmaps migration, so that errors
are handled by just removing unfinished bitmaps, and not fail or try to
recover postcopy migration. Add corresponding test.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727194236.19551-22-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/qemu-iotests/199     | 15 +++++++++++++++
 tests/qemu-iotests/199.out |  4 ++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/199 b/tests/qemu-iotests/199
index 140930b2b12e..58fad872a12c 100755
--- a/tests/qemu-iotests/199
+++ b/tests/qemu-iotests/199
@@ -241,6 +241,21 @@ class TestDirtyBitmapPostcopyMigration(iotests.QMPTestCase):
         self.vm_a.launch()
         check_bitmaps(self.vm_a, 0)

+    def test_early_kill_source(self):
+        self.start_postcopy()
+
+        self.vm_a_events = self.vm_a.get_qmp_events()
+        self.vm_a.kill()
+
+        self.vm_a.launch()
+
+        match = {'data': {'status': 'completed'}}
+        e_complete = self.vm_b.event_wait('MIGRATION', match=match)
+        self.vm_b_events.append(e_complete)
+
+        check_bitmaps(self.vm_a, 0)
+        check_bitmaps(self.vm_b, 0)
+

 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2'])
diff --git a/tests/qemu-iotests/199.out b/tests/qemu-iotests/199.out
index fbc63e62f885..8d7e99670093 100644
--- a/tests/qemu-iotests/199.out
+++ b/tests/qemu-iotests/199.out
@@ -1,5 +1,5 @@
-..
+...
 ----------------------------------------------------------------------
-Ran 2 tests
+Ran 3 tests

 OK
-- 
2.27.0

[PULL 23/24] iotests: Adjust which migration tests are quick

[Eric Blake]

A quick run of './check -qcow2 -g migration' shows that test 169 is
NOT quick, but meanwhile several other tests ARE quick.  Let's adjust
the test designations accordingly.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727195117.132151-1-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 tests/qemu-iotests/group | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 1d0252e1f051..806044642c69 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -112,7 +112,7 @@
 088 rw quick
 089 rw auto quick
 090 rw auto quick
-091 rw migration
+091 rw migration quick
 092 rw quick
 093 throttle
 094 rw quick
@@ -186,7 +186,7 @@
 162 quick
 163 rw
 165 rw quick
-169 rw quick migration
+169 rw migration
 170 rw auto quick
 171 rw quick
 172 auto
@@ -197,9 +197,9 @@
 177 rw auto quick
 178 img
 179 rw auto quick
-181 rw auto migration
+181 rw auto migration quick
 182 rw quick
-183 rw migration
+183 rw migration quick
 184 rw auto quick
 185 rw
 186 rw auto
@@ -216,9 +216,9 @@
 198 rw
 199 rw migration
 200 rw
-201 rw migration
+201 rw migration quick
 202 rw quick
-203 rw auto migration
+203 rw auto migration quick
 204 rw quick
 205 rw quick
 206 rw
-- 
2.27.0

[PULL 24/24] migration: Fix typos in bitmap migration comments

[Eric Blake]

Noticed while reviewing the file for newer patches.

Fixes: b35ebdf076
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200727203206.134996-1-eblake@redhat.com>
---
 migration/block-dirty-bitmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index 1f675b792fc9..784330ebe130 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -97,7 +97,7 @@

 #define DIRTY_BITMAP_MIG_START_FLAG_ENABLED          0x01
 #define DIRTY_BITMAP_MIG_START_FLAG_PERSISTENT       0x02
-/* 0x04 was "AUTOLOAD" flags on elder versions, no it is ignored */
+/* 0x04 was "AUTOLOAD" flags on older versions, now it is ignored */
 #define DIRTY_BITMAP_MIG_START_FLAG_RESERVED_MASK    0xf8

 /* State of one bitmap during save process */
@@ -180,7 +180,7 @@ static uint32_t qemu_get_bitmap_flags(QEMUFile *f)

 static void qemu_put_bitmap_flags(QEMUFile *f, uint32_t flags)
 {
-    /* The code currently do not send flags more than one byte */
+    /* The code currently does not send flags as more than one byte */
     assert(!(flags & (0xffffff00 | DIRTY_BITMAP_MIG_EXTRA_FLAGS)));

     qemu_put_byte(f, flags);
-- 
2.27.0

Re: [PULL 00/24] bitmaps patches for -rc2, 2020-07-27

[Peter Maydell]

On Mon, 27 Jul 2020 at 21:58, Eric Blake <eblake@redhat.com> wrote:
>
> The following changes since commit 9303ecb658a0194560d1eecde165a1511223c2d8:
>
>   Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20200727' into staging (2020-07-27 17:25:06 +0100)
>
> are available in the Git repository at:
>
>   https://repo.or.cz/qemu/ericb.git tags/pull-bitmaps-2020-07-27
>
> for you to fetch changes up to 37931e006f05cb768b78dcc47453b13f76ea43c5:
>
>   migration: Fix typos in bitmap migration comments (2020-07-27 15:42:21 -0500)
>
> ----------------------------------------------------------------
> bitmaps patches for 2020-07-27
>
> - Improve handling of various post-copy bitmap migration scenarios. A lost
> bitmap should merely mean that the next backup must be full rather than
> incremental, rather than abruptly breaking the entire guest migration.
> - Associated iotest improvements


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/5.1
for any user-visible changes.

-- PMM