Register yank functions on sockets to shut them down.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <484c6a14cc2506bebedd5a237259b91363ff8f88.1609167865.git.lukasstraub2@web.de>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

This commit is the result of running the timer-del-timer-free.cocci
script on the whole source tree.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201215154107.3255-4-peter.maydell@linaro.org

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Commit 8118f095 "migration: Append JSON description of migration
stream" needs a JSON writer.  The existing qobject_to_json() wasn't a
good fit, because it requires building a QObject to convert.  Instead,
migration got its very own JSON writer, in commit 190c882c "QJSON:
Add JSON writer".  It tacitly limits numbers to int64_t, and strings
contents to characters that don't need escaping, unlike
qobject_to_json().

The previous commit factored the JSON writer out of qobject_to_json().
Replace migration's JSON writer by it.

Cc: Juan Quintela <quintela@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-17-armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Anywhere we create a list of just one item or by prepending items
(typically because order doesn't matter), we can use
QAPI_LIST_PREPEND().  But places where we must keep the list in order
by appending remain open-coded until later patches.

Note that as a side effect, this also performs a cleanup of two minor
issues in qga/commands-posix.c: the old code was performing
 new = g_malloc0(sizeof(*ret));
which 1) is confusing because you have to verify whether 'new' and
'ret' are variables with the same type, and 2) would conflict with C++
compilation (not an actual problem for this file, but makes
copy-and-paste harder).

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201113011340.463563-5-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
[Straightforward conflicts due to commit a8aa94b5 "qga: update
schema for guest-get-disks 'dependents' field" and commit a10b453a
"target/mips: Move mips_cpu_add_definition() from helper.c to cpu.c"
resolved.  Commit message tweaked.]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

Instead of taking a list parameter and returning a new head at a
distance, just return the new item for the caller to insert into a
list via QAPI_LIST_PREPEND.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201113011340.463563-4-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

Move the property types and property macros implemented in
qdev-properties-system.c to a new qdev-properties-system.h
header.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20201211220529.2290218-16-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

The following steps will cause qemu assertion failure:
- pause vm by executing 'virsh suspend'
- create external snapshot of memory and disk using 'virsh snapshot-create-as'
- doing the above operation again will cause qemu crash

The backtrace looks like:
    at /build/qemu-5.0/migration/savevm.c:1401
    at /build/qemu-5.0/migration/savevm.c:1453

When the first migration completes, bs->open_flags will set BDRV_O_INACTIVE
flag by bdrv_inactivate_all(), and during the second migration the
bdrv_inactivate_recurse assert that the bs->open_flags is already
BDRV_O_INACTIVE enabled which cause crash.

As Vladimir suggested, this patch makes migrate_prepare check the state of vm and
return error if it is in RUN_STATE_POSTMIGRATE state.

Signed-off-by: Tuguoyi <tu.guoyi@h3c.com>
Message-Id: <6b704294ad2e405781c38fb38d68c744@h3c.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reported-by: Li Zhang <li.zhang@cloud.ionos.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@cloud.ionos.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

bdrv_all_create_snapshot() can fails with some snapshots created,
so it's better to delete those snapshots before returns to the caller

Signed-off-by: Tuguoyi <tu.guoyi@h3c.com>
Message-Id: <1607410416-13563-3-git-send-email-tu.guoyi@h3c.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The snapshot in each bs is deleted at the beginning, so there is no need
to find the snapshot again.

Signed-off-by: Tuguoyi <tu.guoyi@h3c.com>
Message-Id: <1607410416-13563-2-git-send-email-tu.guoyi@h3c.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Make qemu_start_incoming_migration local to migration/migration.c.
By using the runstate instead of a separate flag, vl need not do
anything to setup deferred incoming migration.

qmp_migrate_incoming also does not need the deferred_incoming flag
anymore, because "-incoming PROTOCOL" will clear the "once" flag
before the main loop starts.  Therefore, later invocations of
the migrate-incoming command will fail with the existing
"The incoming migration has already been started" error message.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Some very simple initialization routines can be nested in existing
subsystem-level functions, do that to simplify qemu_init.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

There is no "version 2" of the "Lesser" General Public License.
It is either "GPL version 2.0" or "Lesser GPL version 2.1".
This patch replaces all occurrences of "Lesser GPL version 2" with
"Lesser GPL version 2.1" in comment section.

Signed-off-by: Chetan Pant <chetan4windows@gmail.com>
Message-Id: <20201023123130.19656-1-chetan4windows@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

The following sequence may cause the VM abort during migration:

1. RUN_STATE_RUNNING,MIGRATION_STATUS_ACTIVE

2. before call migration_completion(), we send migrate_cancel
   QMP command, the state machine is changed to:
     RUN_STATE_RUNNING,MIGRATION_STATUS_CANCELLING

3. call migration_completion(), and the state machine is
   switch to: RUN_STATE_RUNNING,MIGRATION_STATUS_COMPLETED

4. call migration_iteration_finish(), because the migration
   status is COMPLETED, so it will try to set the runstate
   to POSTMIGRATE, but RUNNING-->POSTMIGRATE is an invalid
   transition, so abort().

The migration_completion() should not change the migration state
to COMPLETED if it is already changed to CANCELLING.

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Message-Id: <20201105091726.148-1-longpeng2@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

When creating new tls client, the tioc->master will be referenced which results in socket
leaking after multifd_save_cleanup if we cancel migration.
Fix it by do object_unref() after tls client creation.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Message-Id: <1605104763-118687-1-git-send-email-zhengchuan@huawei.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Remove redundant blank line which is left by Commit 662770af,
also take this opportunity to remove redundant includes in dirtyrate.c.

Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Message-Id: <1604030281-112946-1-git-send-email-zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

After the WITH_QEMU_LOCK_GUARD macro is added, the compiler cannot identify
 that the statements in the macro must be executed. As a result, some variables
 assignment statements in the macro may be considered as unexecuted by the compiler.

When the -Wmaybe-uninitialized capability is enabled on GCC9,the compiler showed warning:
migration/migration.c: In function ‘migrate_send_rp_req_pages’:
migration/migration.c:384:8: warning: ‘received’ may be used uninitialized in this function [-Wmaybe-uninitialized]
 384 |     if (received) {
     |        ^

Add a default value for 'received' to prevented the warning.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20201111142203.2359370-6-kuhn.chenqun@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The qemu main loop could hang up forever when we enable TLS+Multifd.
The Src multifd_send_0 invokes tls handshake, it sends hello to sever
and wait response.
However, the Dst main qemu loop has been waiting recvmsg() for multifd_recv_1.
Both of Src and Dst main qemu loop are blocking and waiting for reponse which
results in hanging up forever.

Src: (multifd_send_0)                                              Dst: (multifd_recv_1)
multifd_channel_connect                                            migration_channel_process_incoming
  multifd_tls_channel_connect                                        migration_tls_channel_process_incoming
    multifd_tls_channel_connect                                        qio_channel_tls_handshake_task
       qio_channel_tls_handshake                                         gnutls_handshake
          qio_channel_tls_handshake_task                                       ...
            qcrypto_tls_session_handshake                                      ...
              gnutls_handshake                                                 ...
                   ...                                                         ...
                recvmsg (Blocking I/O waiting for response)                recvmsg (Blocking I/O waiting for response)

Fix this by offloadinig handshake work to a background thread.

Reported-by: Yan Jin <jinyan12@huawei.com>
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Message-Id: <1604643893-8223-1-git-send-email-zhengchuan@huawei.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The '%u' conversion specifier is for decimal notation.
When prefixing a format with '0x', we want the hexadecimal
specifier ('%x').

Inspired-by: Dov Murik <dovmurik@linux.vnet.ibm.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20201103112558.2554390-5-philmd@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

we should set ram_bulk_stage to false after ram_state_init,
otherwise the bitmap will be unused in migration_bitmap_find_dirty.
all pages in ram cache will be flushed to the ram of secondary guest
for each checkpoint.

Signed-off-by: Lei Rao <lei.rao@intel.com>
Signed-off-by: Derek Su <dereksu@qnap.com>
Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

The new migrate_send_rp_req_pages_pending() call should greatly improve
destination responsiveness because it will resync faulted address after
postcopy recovery.  However it is also the 1st place to initiate the page
request from the main thread.

One thing is overlooked on that migrate_send_rp_message_req_pages() is not
designed to be thread-safe.  So if we wake the fault thread before syncing all
the faulted pages in the main thread, it means they can race.

Postpone the wake up operation after the sync of faulted addresses.

Fixes: 0c26781c ("migration: Sync requested pages after postcopy recovery")
Tested-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201102153010.11979-3-peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

When postcopy recover happens, we need to reset last_rb after each return of
postcopy_pause_fault_thread() because that means we just got the postcopy
migration continued.

Unify this reset to the place right before we want to kick the fault thread
again, when we get the command MIG_CMD_POSTCOPY_RESUME from source.

This is actually more than that - because the main thread on destination will
now be able to call migrate_send_rp_req_pages_pending() too, so the fault
thread is not the only user of last_rb now.  Move the reset earlier will allow
the first call to migrate_send_rp_req_pages_pending() to use the reset value
even if called from the main thread.

(NOTE: this is not a real fix to 0c26781c mentioned below, however it is just
 a mark that when picking up 0c26781c we'd better have this one too; the real
 fix will come later)

Fixes: 0c26781c ("migration: Sync requested pages after postcopy recovery")
Tested-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20201102153010.11979-2-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Added amount of bytes transferred to the VM at destination by all VFIO
devices

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Logically below race could trigger with the old code:

          test program                        migration thread
          ------------                        ----------------
       wait_until('postcopy-pause')
                                          postcopy_pause()
                                            set_state('postcopy-pause')
       do_postcopy_recover()
         arm s->to_dst_file with new fd
                                            release s->to_dst_file [1]

Here [1] could have released the just-installed recoverying channel.  Then the
migration could hang without really resuming.

Instead, it should be very safe to release the fd before setting the state into
'postcopy-pause', because there's no reason for any other thread to touch it
during 'postcopy-active'.

Dave reported a very rare postcopy recovery hang that the migration-test
program waited for the migration to complete in migrate_postcopy_complete().
We do suspect it's the same thing that we're gonna fix here.  Hard to tell.
However since we've noticed this, fix this irrelevant of the hang report.

Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201021212721.440373-6-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

We synchronize the requested pages right after a postcopy recovery happens.
This helps to synchronize the prioritized pages on source so that the faulted
threads can be served faster.

Reported-by: Xiaohui Li <xiaohli@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201021212721.440373-5-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Maintain a list of faulted addresses on the destination host for which we're
waiting on.  This is implemented using a GTree rather than a real list to make
sure even there're plenty of vCPUs/threads that are faulting, the lookup will
still be fast with O(log(N)) (because we'll do that after placing each page).
It should bring a slight overhead, but ideally that shouldn't be a big problem
simply because in most cases the requested page list will be short.

Actually we did similar things for postcopy blocktime measurements.  This patch
didn't use that simply because:

  (1) blocktime measurement is towards vcpu threads only, but here we need to
      record all faulted addresses, including main thread and external
      thread (like, DPDK via vhost-user).

  (2) blocktime measurement will require UFFD_FEATURE_THREAD_ID, but here we
      don't want to add that extra dependency on the kernel version since not
      necessary.  E.g., we don't need to know which thread faulted on which
      page, we also don't care about multiple threads faulting on the same
      page.  But we only care about what addresses are faulted so waiting for a
      page copying from src.

  (3) blocktime measurement is not enabled by default.  However we need this by
      default especially for postcopy recover.

Another thing to mention is that this patch introduced a new mutex to serialize
the receivedmap and the page_requested tree, however that serialization does
not cover other procedures like UFFDIO_COPY.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201021212721.440373-4-peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

This is another layer wrapper for sending a page request to the source VM.  The
new migrate_send_rp_message_req_pages() will be used elsewhere in coming
patches.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201021212721.440373-3-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

It'll be used in follow up patches to access more fields out of it.  Meanwhile
fetch the userfaultfd inside the function.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20201021212721.440373-2-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Message-Id: <1603179176-5360-1-git-send-email-yubihong@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1603163448-27122-9-git-send-email-yubihong@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1603163448-27122-8-git-send-email-yubihong@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1603163448-27122-7-git-send-email-yubihong@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1603163448-27122-6-git-send-email-yubihong@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1603163448-27122-5-git-send-email-yubihong@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1603163448-27122-4-git-send-email-yubihong@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <1603163448-27122-3-git-send-email-yubihong@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Bihong Yu <yubihong@huawei.com>
Reviewed-by: Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <1603163448-27122-2-git-send-email-yubihong@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Commit ef96e3ae in January 2019 removed the last user of the
VMSTATE_FLOAT64* macros. These were used by targets which defined
their floating point register file as an array of 'float64'.

We used to try to maintain a stricter distinction between
'float64' (a type for holding an integer representing an IEEE float)
and 'uint64_t', including having a debug option for 'float64' being
a struct and supposedly mandatory macros for converting between
float64 and uint64_t. We no longer think that's a usefully
strong distinction to draw and we allow ourselves to freely
assume that float64 really is just a 64-bit integer type, so
for new targets we would simply recommend use of the uint64_t type
for a floating point register file. The float64 type remains
as a useful way of documenting in the type signature of helper
functions and the like that they expect to receive an IEEE float
from the TCG generated code rather than an arbitrary integer.

Since the VMSTATE_FLOAT64* macros have no remaining users and
we don't recommend new code uses them, delete them.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20201022120830.5938-1-peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

A default value is provided for the variable 'bitmap_name' to avoid
a compiler warning.

The compiler showed the warning:
migration/block-dirty-bitmap.c:1090:13: warning: ‘bitmap_name’
may be used uninitialized in this function [-Wmaybe-uninitialized]
       g_strlcpy(s->bitmap_name, bitmap_name, sizeof(s->bitmap_name));
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Message-Id: <20201014114430.1898684-1-kuhn.chenqun@huawei.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: commit message grammar tweaks]
Signed-off-by: Eric Blake <eblake@redhat.com>

sectors_per_chunk is a 64 bit integer, but the calculation is done in 32
bits, leading to an overflow for coarse bitmap granularities.

If that results in the value 0, it leads to a hang where no progress is
made but send_bitmap_bits is constantly called with nr_sectors being 0.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Message-Id: <20201021144456.1072-1-s.reiter@proxmox.com>
Fixes: b35ebdf0 migration: add postcopy migration of dirty bitmaps
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: Use correct type for 8ULL, use () to avoid overflow]
Signed-off-by: Eric Blake <eblake@redhat.com>