Postcopy may also be advised for dirty-bitmap migration only, in which
case the remote page size will not be available and we'll instead read
bogus data, blocking migration with a mismatch error if the VM uses
hugepages.

Fixes: 58110f0a ("migration: split common postcopy out of ram postcopy")
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Message-Id: <20210204163522.13291-1-s.reiter@proxmox.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

savevm, loadvm and delvm are some of the few HMP commands that have never
been converted to use QMP. The reasons for the lack of conversion are
that they blocked execution of the event thread, and the semantics
around choice of disks were ill-defined.

Despite this downside, however, libvirt and applications using libvirt
have used these commands for as long as QMP has existed, via the
"human-monitor-command" passthrough command. IOW, while it is clearly
desirable to be able to fix the problems, they are not a blocker to
all real world usage.

Meanwhile there is a need for other features which involve adding new
parameters to the commands. This is possible with HMP passthrough, but
it provides no reliable way for apps to introspect features, so using
QAPI modelling is highly desirable.

This patch thus introduces new snapshot-{load,save,delete} commands to
QMP that are intended to replace the old HMP counterparts. The new
commands are given different names, because they will be using the new
QEMU job framework and thus will have diverging behaviour from the HMP
originals. It would thus be misleading to keep the same name.

While this design uses the generic job framework, the current impl is
still blocking. The intention that the blocking problem is fixed later.
None the less applications using these new commands should assume that
they are asynchronous and thus wait for the job status change event to
indicate completion.

In addition to using the job framework, the new commands require the
caller to be explicit about all the block device nodes used in the
snapshot operations, with no built-in default heuristics in use.

Note that the existing "query-named-block-nodes" can be used to query
what snapshots currently exist for block nodes.

Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-13-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  dgilbert: removed tests for now, the output ordering isn't
deterministic

Make snapshot deletion consistent with the snapshot save
and load commands by using a wrapper around the blockdev
layer. The main difference is that we get upfront validation
of the passed in device list (if any).

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-10-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Modify load_snapshot/save_snapshot to accept the device list and vmstate
node name parameters previously added to the block layer.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-9-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The traditional HMP "savevm" command will overwrite an existing snapshot
if it already exists with the requested name. This new flag allows this
to be controlled allowing for safer behaviour with a future QMP command.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-8-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Currently bdrv_all_find_snapshot() will return 0 if it finds
a snapshot, -1 if an error occurs, or if it fails to find a
snapshot. New callers to be added want to distinguish between
the error scenario and failing to find a snapshot.

Rename it to bdrv_all_has_snapshot and make it return -1 on
error, 0 if no snapshot is found and 1 if snapshot is found.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-7-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Currently the vmstate will be stored in the first block device that
supports snapshots. Historically this would have usually been the
root device, but with UEFI it might be the variable store. There
needs to be a way to override the choice of block device to store
the state in.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-6-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

When running snapshot operations, there are various rules for which
blockdevs are included/excluded. While this provides reasonable default
behaviour, there are scenarios that are not well handled by the default
logic. Some of the conditions do not have a single correct answer.

Thus there needs to be a way for the mgmt app to provide an explicit
list of blockdevs to perform snapshots across. This can be achieved
by passing a list of node names that should be used.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210204124834.774401-5-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

None of the callers care about the errno value since there is a full
Error object populated. This gives consistency with save_snapshot()
which already just returns a boolean value.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Return false/true instead of -1/0, document function]
Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210204124834.774401-4-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Just for consistency, following the example documented since
commit e3fe3988 ("error: Document Error API usage rules"),
return a boolean value indicating an error is set or not.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210204124834.774401-3-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The bdrv_all_*_snapshot functions return a BlockDriverState pointer
for the invalid backend, which the callers then use to report an
error message. In some cases multiple callers are reporting the
same error message, but with slightly different text. In the future
there will be more error scenarios for some of these methods, which
will benefit from fine grained error message reporting. So it is
helpful to push error reporting down a level.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Initialize variables]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210204124834.774401-2-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Modify query-migrate so that it has a flag indicating if outbound
migration is blocked, and if it is a list of reasons.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210202135522.127380-2-dgilbert@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migrate_params_check() has a number of error messages of the form

    Parameter 'NAME' expects is invalid, it should be ...

Fix them to something like

    Parameter 'NAME' expects a ...

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210202141734.2488076-5-armbru@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

cache_init() attempts to handle allocation failure.  The two error
messages are garbage, as untested error messages commonly are:

    Parameter 'cache size' expects Failed to allocate cache
    Parameter 'cache size' expects Failed to allocate page cache

Fix them to just

    Failed to allocate cache
    Failed to allocate page cache

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210202141734.2488076-4-armbru@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

73af8dd8 "migration: Make xbzrle_cache_size a migration
parameter" (v2.11.0) made the new parameter unsigned (QAPI type
'size', uint64_t in C).  It neglected to update existing code, which
continues to use int64_t.

migrate_xbzrle_cache_size() returns the new parameter.  Adjust its
return type.

QMP query-migrate-cache-size returns migrate_xbzrle_cache_size().
Adjust its return type.

migrate-set-parameters passes the new parameter to
xbzrle_cache_resize().  Adjust its parameter type.

xbzrle_cache_resize() passes it on to cache_init().  Adjust its
parameter type.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210202141734.2488076-3-armbru@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Introducing implementation of 'background' snapshot thread
which in overall follows the logic of precopy migration
while internally utilizes completely different mechanism
to 'freeze' vmstate at the start of snapshot creation.

This mechanism is based on userfault_fd with wr-protection
support and is Linux-specific.

Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210129101407.103458-5-andrey.gruzdev@virtuozzo.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

In this particular implementation the same single migration
thread is responsible for both normal linear dirty page
migration and procesing UFFD page fault events.

Processing write faults includes reading UFFD file descriptor,
finding respective RAM block and saving faulting page to
the migration stream. After page has been saved, write protection
can be removed. Since asynchronous version of qemu_put_buffer()
is expected to be used to save pages, we also have to flush
migraion stream prior to un-protecting saved memory range.

Write protection is being removed for any previously protected
memory chunk that has hit the migration stream. That's valid
for pages from linear page scan along with write fault pages.

Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210129101407.103458-4-andrey.gruzdev@virtuozzo.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  fixup pagefault.address cast for 32bit

Add new capability to 'qapi/migration.json' schema.
Update migrate_caps_check() to validate enabled capability set
against introduced one. Perform checks for required kernel features
and compatibility with guest memory backends.

Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210129101407.103458-2-andrey.gruzdev@virtuozzo.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Fixed error when compiling migration/qemu-file.c with -Werror=maybe-uninitialized
as shown here:

../migration/qemu-file.c: In function 'qemu_get_buffer_in_place':
../migration/qemu-file.c:604:18: error: 'src' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  604 |             *buf = src;
      |             ~~~~~^~~~~
cc1: all warnings being treated as errors

Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Message-Id: <20210128130625.569900-1-wainersm@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

When VM migrate VMState of configuration, the fields(name and capabilities)
of configuration having a flag of VMS_ALLOC need to allocate memory. If the
src doesn't free memory of capabilities in SaveState after save VMState of
configuration, or the dst doesn't free memory of name and capabilities in post
load of configuration, it may result in memory leak of name and capabilities.
We free memory in configuration_post_save and configuration_post_load func,
which prevents memory leak.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Jinhao Gao <gaojinhao@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20201231061020.828-3-gaojinhao@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

These cases require a bit more thought to review; in each case, the
code was appending to a list, but not with a FOOList **tail variable.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210113221013.390592-6-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Flawed change to qmp_guest_network_get_interfaces() dropped]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

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>