The migrate command is one of those commands where HMP and QMP completely
mix up together. This made the conversion to the QAPI (which separates the
command into QMP and HMP parts) a bit difficult.

The first important change to be noticed is that this commit completes the
removal of the Monitor object from migration code, started by the previous
commit.

Another important and tricky change is about supporting the non-detached
mode. That is, if the user doesn't pass '-d' the migrate command will lock
the monitor and will only release it when migration is finished.

To support this in the new HMP command (hmp_migrate()), it is necessary
to create a timer which runs every second and checks if the migration is
still active. If it is, the timer callback will re-schedule itself to run
one second in the future. If the migration has already finished, the
monitor lock is released and the user can use it normally.

All these changes should be transparent to the user.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

The Monitor object is passed back and forth within the migration/savevm
code so that it can print errors and progress to the user.

However, that approach assumes a HMP monitor, being completely invalid
in QMP.

This commit drops almost every single usage of the Monitor object, all
monitor_printf() calls have been converted into DPRINTF() ones.

There are a few remaining Monitor objects, those are going to be dropped
by the next commit.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Notifiers do not need to access both ends of the list, and using
a QLIST also simplifies the API.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

All files under GPLv2 will get GPLv2+ changes starting tomorrow.
event_notifier.c and exec-obsolete.h were only ever touched by Red Hat
employees and can be relicensed now.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Also, we now return the qemu_fclose() value unchanged to the caller. For
reference, the migrate_fd_cleanup() callers are the following:

- migrate_fd_completed(): any negative value is considered an
  error, so the change is OK.
- migrate_fd_error(): doesn't check the migrate_fd_cleanup() return value
- migrate_fd_cancel(): doesn't check the migrate_fd_cleanup() return
  value
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Image files have two types of data: immutable data that describes things like
image size, backing files, etc. and mutable data that includes offset and
reference count tables.

Today, image formats aggressively cache mutable data to improve performance.  In
some cases, this happens before a guest even starts.  When dealing with live
migration, since a file is open on two machines, the caching of meta data can
lead to data corruption.

This patch addresses this by introducing a mechanism to invalidate any cached
mutable data a block driver may have which is then used by the live migration
code.

NB, this still requires coherent shared storage.  Addressing migration without
coherent shared storage (i.e. NFS) requires additional work.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

This lets different subsystems register an Error that is thrown whenever
migration is attempted.  This works nicely because it gracefully supports
things like hotplug.

Right now, if multiple errors are registered, only one of them is reported.
I expect that for 1.1, we'll extend query-migrate to return all of the reasons
why migration is disabled at any given point in time.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Migration with fd uses s->mon to pass the fd.  But we only assign the
s->mon for !detached migration.  Fix it.  Once there add a comment
indicating that s->mon has two uses.

Bug reported by:  Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>
CC:  Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

A simple migration reproduces it:

1. Start the source VM with:

   # qemu [...] -S

2. Start the destination VM with:

   # qemu <source VM cmd-line> -incoming tcp:0:4444

3. In the source VM:

   (qemu) migrate -d tcp:0:4444

4. The source VM will segfault as soon as migration completes (might not
   happen in the first try)

What is happening here is that qemu_file_put_notify() can end up closing
's->file' (in which case it's also set to NULL). The call stack is rather
complex, but Eduardo helped tracking it to:

select loop -> migrate_fd_put_notify() -> qemu_file_put_notify() ->
buffered_put_buffer() -> migrate_fd_put_ready() ->
migrate_fd_completed() -> migrate_fd_cleanup().

To be honest, it's not completely clear to me in which cases 's->file'
is not closed (on error maybe)? But I doubt this fix will make anything
worse.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

Add migration_is_active and migration_has_failed functions
to query migration state.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

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

This will allow us to hide the state values.
Signed-off-by: NJuan Quintela <quintela@redhat.com>

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

Now that current_migration always exist, there is no reason for
max_throotle variable.
Signed-off-by: NJuan Quintela <quintela@redhat.com>

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

This means we can remove the two forward declarations.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

It is used only in one place
Signed-off-by: NJuan Quintela <quintela@redhat.com>

It is only used inside migration.c, and fields on that struct are
accessed all around the place on that file.
Signed-off-by: NJuan Quintela <quintela@redhat.com>

We called it from a single place, and always with state !=
MIG_STATE_ACTIVE.  Just remove the whole callback.  For users of the
notifier, notice that this is exactly the case where they don't care,
we are just freeing the state from previous failed migration (it can't
be a sucessful one, otherwise we would not be running on that machine
in the first place).
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

This function is a bit different of the others that change the state,
in the sense that if migrate_fd_cleanup() returns an error, it set the
status to error, not completed.
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Use MIG_STATE_ACTIVE only when migration has really started.  Use this
new state to setup migration parameters.  Change defines for an
anonymous struct.
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Once there, remove all parameters that don't need to be passed to
*start_outgoing_migration() functions
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

I have to move two functions postions to avoid forward declarations
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Now the function returned errno, so it is better the new name.
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

make functions propagate errno, instead of just using -EIO.  Add a
comment about what are the return value of qemu_savevm_state_iterate().
Signed-off-by: NJuan Quintela <quintela@redhat.com>

We normally already have an errno value.  When not, abuse EIO.
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

If migration is not active, just ignore writes.
Signed-off-by: NJuan Quintela <quintela@redhat.com>

Although migrate_fd_put_buffer() sets MIG_STATE_ERROR if it failed,
since migrate_fd_put_notify() isn't checking error of underlying
QEMUFile, those resources are kept open.  This patch checks it and
calls migrate_fd_error() in case of error.
Signed-off-by: NYoshiaki Tamura <tamura.yoshiaki@lab.ntt.co.jp>
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>