Update the migration docs:

Among other changes:
  * Added a general list of advice for device authors
  * Reordered the section on conditional state (subsections etc)
    into the order we prefer.
  * Add a note about firmware
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NPeter Xu <peterx@redhat.com>
Reviewed-by: NBalamuruhan S <bala24@linux.vnet.ibm.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Message-Id: <20180503191059.19576-1-dgilbert@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Wrapper for QMP command "migrate-pause".
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-25-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

It pauses an ongoing migration.  Currently it only supports postcopy.
Note that this command will work on either side of the migration.
Basically when we trigger this on one side, it'll interrupt the other
side as well since the other side will get notified on the disconnect
event.

However, it's still possible that the other side is not notified, for
example, when the network is totally broken, or due to some firewall
configuration changes.  In that case, we will also need to run the same
command on the other side so both sides will go into the paused state.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-24-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

---
s/2.12/2.13/

Let's introduce a lock for that QEMUFile since we are going to operate
on it in multiple threads.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-23-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Sister command to migrate-recover in QMP.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-22-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

The first allow-oob=true command.  It's used on destination side when
the postcopy migration is paused and ready for a recovery.  After
execution, a new migration channel will be established for postcopy to
continue.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-21-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>
---
s/2.12/2.13/

Though we may not need it, now we init both the src/dst migration
objects in migration_object_init() so that even incoming migration
object would be thread safe (it was not).
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-20-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Finish the last step to do the final handshake for the recovery.

First source sends one MIG_CMD_RESUME to dst, telling that source is
ready to resume.

Then, dest replies with MIG_RP_MSG_RESUME_ACK to source, telling that
dest is ready to resume (after switch to postcopy-active state).

When source received the RESUME_ACK, it switches its state to
postcopy-active, and finally the recovery is completed.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-19-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

After we updated the dirty bitmaps of ramblocks, we also need to update
the critical fields in RAMState to make sure it is ready for a resume.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-18-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

This patch implements the first part of core RAM resume logic for
postcopy. ram_resume_prepare() is provided for the work.

When the migration is interrupted by network failure, the dirty bitmap
on the source side will be meaningless, because even the dirty bit is
cleared, it is still possible that the sent page was lost along the way
to destination. Here instead of continue the migration with the old
dirty bitmap on source, we ask the destination side to send back its
received bitmap, then invert it to be our initial dirty bitmap.

The source side send thread will issue the MIG_CMD_RECV_BITMAP requests,
once per ramblock, to ask for the received bitmap. On destination side,
MIG_RP_MSG_RECV_BITMAP will be issued, along with the requested bitmap.
Data will be received on the return-path thread of source, and the main
migration thread will be notified when all the ramblock bitmaps are
synchronized.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-17-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

This is hook function to be called when a postcopy migration wants to
resume from a failure. For each module, it should provide its own
recovery logic before we switch to the postcopy-active state.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-16-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Creating new message to reply for MIG_CMD_POSTCOPY_RESUME. One uint32_t
is used as payload to let the source know whether destination is ready
to continue the migration.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-15-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Introducing this new command to be sent when the source VM is ready to
resume the paused migration.  What the destination does here is
basically release the fault thread to continue service page faults.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-14-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Introducing new return path message MIG_RP_MSG_RECV_BITMAP to send
received bitmap of ramblock back to source.

This is the reply message of MIG_CMD_RECV_BITMAP, it contains not only
the header (including the ramblock name), and it was appended with the
whole ramblock received bitmap on the destination side.

When the source receives such a reply message (MIG_RP_MSG_RECV_BITMAP),
it parses it, convert it to the dirty bitmap by inverting the bits.

One thing to mention is that, when we send the recv bitmap, we are doing
these things in extra:

- converting the bitmap to little endian, to support when hosts are
  using different endianess on src/dst.

- do proper alignment for 8 bytes, to support when hosts are using
  different word size (32/64 bits) on src/dst.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-13-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Add a new vm command MIG_CMD_RECV_BITMAP to request received bitmap for
one ramblock.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-12-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

On the destination side, we cannot wake up all the threads when we got
reconnected. The first thing to do is to wake up the main load thread,
so that we can continue to receive valid messages from source again and
reply when needed.

At this point, we switch the destination VM state from postcopy-paused
back to postcopy-recover.

Now we are finally ready to do the resume logic.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-11-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Introducing new migration state "postcopy-recover". If a migration
procedure is paused and the connection is rebuilt afterward
successfully, we'll switch the source VM state from "postcopy-paused" to
the new state "postcopy-recover", then we'll do the resume logic in the
migration thread (along with the return path thread).

This patch only do the state switch on source side. Another following up
patch will handle the state switching on destination side using the same
status bit.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-10-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

---
s/2.11/2.13/

This patch detects the "resume" flag of migration command, rebuild the
channels only if the flag is set.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-9-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

It will be used when we want to resume one paused migration.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-8-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>
---
s/2.12/2.13/

Allows the fault thread to stop handling page faults temporarily. When
network failure happened (and if we expect a recovery afterwards), we
should not allow the fault thread to continue sending things to source,
instead, it should halt for a while until the connection is rebuilt.

When the dest main thread noticed the failure, it kicks the fault thread
to switch to pause state.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-7-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Let the thread pause for network issues.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-6-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

When there is IO error on the incoming channel (e.g., network down),
instead of bailing out immediately, we allow the dst vm to switch to the
new POSTCOPY_PAUSE state. Currently it is still simple - it waits the
new semaphore, until someone poke it for another attempt.

One note is that here on ram loading thread we cannot detect the
POSTCOPY_ACTIVE state, but we need to detect the more specific
POSTCOPY_INCOMING_RUNNING state, to make sure we have already loaded all
the device states.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-5-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Now when network down for postcopy, the source side will not fail the
migration. Instead we convert the status into this new paused state, and
we will try to wait for a rescue in the future.

If a recovery is detected, migration_thread() will reset its local
variables to prepare for that.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-4-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Introducing a new state "postcopy-paused", which can be used when the
postcopy migration is paused. It is targeted for postcopy network
failure recovery.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-3-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

The old incoming migration is running in main thread and default
gcontext.  With the new qio_channel_add_watch_full() we can now let it
run in the thread's own gcontext (if there is one).

Currently this patch does nothing alone.  But when any of the incoming
migration is run in another iothread (e.g., the upcoming migrate-recover
command), this patch will bind the incoming logic to the iothread
instead of the main thread (which may already get page faulted and
hanged).

RDMA is not considered for now since it's not even using the QIO watch
framework at all.
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-2-peterx@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Once there, we don't need the struct names anywhere, just the
typedefs.  And now also document all fields.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

--

Be network agnostic.
Add error checking for all values.

We need to make sure that we have started all the multifd threads.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

In both sides.  We still don't transmit anything through them.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

We need them before we start migration.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

Once there, make  count field to always be accessed with atomic
operations.  To make blocking operations, we need to know that the
thread is running, so create a bool to indicate that.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

--

Once here, s/terminate_multifd_*-threads/multifd_*_terminate_threads/
This is consistente with every other function

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>

No need to write it to a file.  Just need a proper firmware O:-)
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NLaurent Vivier <lvivier@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NPeter Xu <peterx@redhat.com>

Fix the bug introduced by da3f56cb (migration: remove
ram_save_compressed_page()), It should be 'return' rather than
'res'

Sorry for this stupid mistake :(
Signed-off-by: NXiao Guangrong <xiaoguangrong@tencent.com>
Message-Id: <20180428081045.8878-1-xiaoguangrong@tencent.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Block layer patches:

- Switch AIO/callback based block drivers to a byte-based interface
- Block jobs: Expose error string via query-block-jobs
- Block job cleanups and fixes
- hmp: Allow using a qdev id in block_set_io_throttle

# gpg: Signature made Tue 15 May 2018 16:33:10 BST
# gpg:                using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream: (37 commits)
  iotests: Add test for -U/force-share conflicts
  qemu-img: Use only string options in img_open_opts
  qemu-io: Use purely string blockdev options
  block: Document BDRV_REQ_WRITE_UNCHANGED support
  qemu-img: Check post-truncation size
  iotests: Add test for COR across nodes
  iotests: Copy 197 for COR filter driver
  iotests: Clean up wrap image in 197
  block: Support BDRV_REQ_WRITE_UNCHANGED in filters
  block/quorum: Support BDRV_REQ_WRITE_UNCHANGED
  block: Set BDRV_REQ_WRITE_UNCHANGED for COR writes
  block: Add BDRV_REQ_WRITE_UNCHANGED flag
  block: BLK_PERM_WRITE includes ..._UNCHANGED
  block: Add COR filter driver
  iotests: Skip 181 and 201 without userfaultfd
  iotests: Add failure matching to common.qemu
  docs: Document the new default sizes of the qcow2 caches
  qcow2: Give the refcount cache the minimum possible size by default
  specs/qcow2: Clarify that compressed clusters have the COPIED bit reset
  Fix error message about compressed clusters with OFLAG_COPIED
  ...
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

- Copy-on-read block driver
- The qcow2 default refcount cache size has been decreased
- Various bug fixes

# gpg: Signature made Tue May 15 16:18:25 2018 CEST
# gpg:                using RSA key F407DB0061D5CF40
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>"
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* mreitz/tags/pull-block-2018-05-15: (21 commits)
  iotests: Add test for -U/force-share conflicts
  qemu-img: Use only string options in img_open_opts
  qemu-io: Use purely string blockdev options
  block: Document BDRV_REQ_WRITE_UNCHANGED support
  qemu-img: Check post-truncation size
  iotests: Add test for COR across nodes
  iotests: Copy 197 for COR filter driver
  iotests: Clean up wrap image in 197
  block: Support BDRV_REQ_WRITE_UNCHANGED in filters
  block/quorum: Support BDRV_REQ_WRITE_UNCHANGED
  block: Set BDRV_REQ_WRITE_UNCHANGED for COR writes
  block: Add BDRV_REQ_WRITE_UNCHANGED flag
  block: BLK_PERM_WRITE includes ..._UNCHANGED
  block: Add COR filter driver
  iotests: Skip 181 and 201 without userfaultfd
  iotests: Add failure matching to common.qemu
  docs: Document the new default sizes of the qcow2 caches
  qcow2: Give the refcount cache the minimum possible size by default
  specs/qcow2: Clarify that compressed clusters have the COPIED bit reset
  Fix error message about compressed clusters with OFLAG_COPIED
  ...
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NMax Reitz <mreitz@redhat.com>
Message-id: 20180502202051.15493-4-mreitz@redhat.com
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>