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: Anthony 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: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Anthony 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: Juan Quintela <quintela@redhat.com>
CC: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Anthony 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: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This means we can remove the two forward declarations.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.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: Juan 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: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony 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: Juan Quintela <quintela@redhat.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: Juan Quintela <quintela@redhat.com>
Once there, remove all parameters that don't need to be passed to
*start_outgoing_migration() functions
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
I have to move two functions postions to avoid forward declarations
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Now the function returned errno, so it is better the new name.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony 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: Juan 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: Yoshiaki Tamura <tamura.yoshiaki@lab.ntt.co.jp>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Once there, make sure that if we already know that there is one error,
just call migration_fd_cleanup() with the ERROR state.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
It should be a matter of allowing the transition POSTMIGRATE ->
FINISH_MIGRATE, but it turns out that the VM won't do the
transition the second time because it's already stopped.
So this commit also adds vm_stop_force_state() which performs
the transition even if the VM is already stopped.
While there also allow other states to migrate.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Next commit will convert the query-status command to use the
RunState type as generated by the QAPI.
In order to "transparently" replace the current enum by the QAPI
one, we have to make some changes to some enum values.
As the changes are simple renames, I'll do them in one shot. The
changes are:
- Rename the prefix from RSTATE_ to RUN_STATE_
- RUN_STATE_SAVEVM to RUN_STATE_SAVE_VM
- RUN_STATE_IN_MIGRATE to RUN_STATE_INMIGRATE
- RUN_STATE_PANICKED to RUN_STATE_INTERNAL_ERROR
- RUN_STATE_POST_MIGRATE to RUN_STATE_POSTMIGRATE
- RUN_STATE_PRE_LAUNCH to RUN_STATE_PRELAUNCH
- RUN_STATE_PRE_MIGRATE to RUN_STATE_PREMIGRATE
- RUN_STATE_RESTORE to RUN_STATE_RESTORE_VM
- RUN_STATE_PRE_MIGRATE to RUN_STATE_FINISH_MIGRATE
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Test against RSTATE_IN_MIGRATE instead.
Please, note that the RSTATE_IN_MIGRATE state is only set when all the
initial VM setup is done, while 'incoming_expected' was set right in
the beginning when parsing command-line options. Shouldn't be a problem
as far as I could check.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Currently, only vm_start() and vm_stop() change the VM state.
That's, the state is only changed when starting or stopping the VM.
This commit adds the runstate_set() function, which makes it possible
to also do state transitions when the VM is stopped or running.
Additional states are also added and the current state is stored.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Today, when notifying a VM state change with vm_state_notify(),
we pass a VMSTOP macro as the 'reason' argument. This is not ideal
because the VMSTOP macros tell why qemu stopped and not exactly
what the current VM state is.
One example to demonstrate this problem is that vm_start() calls
vm_state_notify() with reason=0, which turns out to be VMSTOP_USER.
This commit fixes that by replacing the VMSTOP macros with a proper
state type called RunState.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
If migration failed in migrate_fd_put_buffer, the monitor may have been
resumed not only in the error path of that function but also once again
in migrate_fd_put_ready which is called unconditionally by
migrate_fd_connect.
Fix this by establishing a cleaner policy: the monitor shall be resumed
when the migration file is closed, either via callback
(migrate_fd_close) or in migrate_fd_cleanup if no file is open (i.e. no
callback invoked).
Reported-By: Michael Tokarev <mjt@tls.msk.ru>
Tested-By: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This allows to pass additional information to the notifier callback
which is useful if sender and receiver do not share any other distinct
data structure.
Will be used first for the clock reset notifier.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Define and use dedicated constants for vm_stop reasons, they actually
have nothing to do with the EXCP_* defines used so far. At this chance,
specify more detailed reasons so that VM state change handlers can
evaluate them.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This patch adds functions to register and unregister notifiers for
migration state changes and a function to query the migration state.
The notifier is called on every state change. Once after establishing a
new migration object (which is in active state then) and once when the
state changes from active to completed, canceled or error.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
The no_migrate save state flag is currently only checked in the
last phase of migration. This means that we potentially waste
a lot of time and bandwidth with the live state handlers before
we ever check the no_migrate flags. The error message printed
when we catch a non-migratable device doesn't get printed for
a detached migration. And, no_migrate does nothing to prevent
an incoming migration to a target that includes a non-migratable
device. This attempts to fix all of these.
One notable difference in behavior is that an outgoing migration
now checks for non-migratable devices before ever connecting to
the target system. This means the target will remain listening
rather than exit from failure.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
There's no need to flush requests after vmstop
as vmstop does it for us automatically now.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Jason Wang <jasowang@redhat.com>
I'd like to disable bandwidth limit or make it very high,
Use int64_t all over to make values >= 4g work.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Jason Wang <jasowang@redhat.com>
