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* migration/postcopy: Add postcopy-recover-setup phasePeter Xu2024-06-211-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds a migration state on src called "postcopy-recover-setup". The new state will describe the intermediate step starting from when the src QEMU received a postcopy recovery request, until the migration channels are properly established, but before the recovery process take place. The request came from Libvirt where Libvirt currently rely on the migration state events to detect migration state changes. That works for most of the migration process but except postcopy recovery failures at the beginning. Currently postcopy recovery only has two major states: - postcopy-paused: this is the state that both sides of QEMU will be in for a long time as long as the migration channel was interrupted. - postcopy-recover: this is the state where both sides of QEMU handshake with each other, preparing for a continuation of postcopy which used to be interrupted. The issue here is when the recovery port is invalid, the src QEMU will take the URI/channels, noticing the ports are not valid, and it'll silently keep in the postcopy-paused state, with no event sent to Libvirt. In this case, the only thing Libvirt can do is to poll the migration status with a proper interval, however that's less optimal. Considering that this is the only case where Libvirt won't get a notification from QEMU on such events, let's add postcopy-recover-setup state to mimic what we have with the "setup" state of a newly initialized migration, describing the phase of connection establishment. With that, postcopy recovery will have two paths to go now, and either path will guarantee an event generated. Now the events will look like this during a recovery process on src QEMU: - Initially when the recovery is initiated on src, QEMU will go from "postcopy-paused" -> "postcopy-recover-setup". Old QEMUs don't have this event. - Depending on whether the channel re-establishment is succeeded: - In succeeded case, src QEMU will move from "postcopy-recover-setup" to "postcopy-recover". Old QEMUs also have this event. - In failure case, src QEMU will move from "postcopy-recover-setup" to "postcopy-paused" again. Old QEMUs don't have this event. This guarantees that Libvirt will always receive a notification for recovery process properly. One thing to mention is, such new status is only needed on src QEMU not both. On dest QEMU, the state machine doesn't change. Hence the events don't change either. It's done like so because dest QEMU may not have an explicit point of setup start. E.g., it can happen that when dest QEMUs doesn't use migrate-recover command to use a new URI/channel, but the old URI/channels can be reused in recovery, in which case the old ports simply can work again after the network routes are fixed up. Add a new helper postcopy_is_paused() detecting whether postcopy is still paused, taking RECOVER_SETUP into account too. When using it on both src/dst, a slight change is done altogether to always wait for the semaphore before checking the status, because for both sides a sem_post() will be required for a recovery. Cc: Jiri Denemark <jdenemar@redhat.com> Cc: Prasad Pandit <ppandit@redhat.com> Reviewed-by: Fabiano Rosas <farosas@suse.de> Buglink: https://issues.redhat.com/browse/RHEL-38485 Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Fabiano Rosas <farosas@suse.de>
* migration: remove error from notifier dataSteve Sistare2024-02-281-1/+0
| | | | | | | | | | | Remove the error object from opaque data passed to notifiers. Use the new error parameter passed to the notifier instead. Signed-off-by: Steve Sistare <steven.sistare@oracle.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/r/1708622920-68779-3-git-send-email-steven.sistare@oracle.com Signed-off-by: Peter Xu <peterx@redhat.com>
* migration: Allow postcopy_ram_supported_by_host() to report errPeter Xu2023-04-271-1/+2
| | | | | | | | | | | | | | | | | | | | Instead of print it to STDERR, bring the error upwards so that it can be reported via QMP responses. E.g.: { "execute": "migrate-set-capabilities" , "arguments": { "capabilities": [ { "capability": "postcopy-ram", "state": true } ] } } { "error": { "class": "GenericError", "desc": "Postcopy is not supported: Host backend files need to be TMPFS or HUGETLBFS only" } } Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
* migration: Postpone postcopy preempt channel to be after mainPeter Xu2023-02-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Postcopy with preempt-mode enabled needs two channels to communicate. The order of channel establishment is not guaranteed. It can happen that the dest QEMU got the preempt channel connection request before the main channel is established, then the migration may make no progress even during precopy due to the wrong order. To fix it, create the preempt channel only if we know the main channel is established. For a general postcopy migration, we delay it until postcopy_start(), that's where we already went through some part of precopy on the main channel. To make sure dest QEMU has already established the channel, we wait until we got the first PONG received. That's something we do at the start of precopy when postcopy enabled so it's guaranteed to happen sooner or later. For a postcopy recovery, we delay it to qemu_savevm_state_resume_prepare() where we'll have round trips of data on bitmap synchronizations, which means the main channel must have been established. Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
* migration: Cleanup postcopy_preempt_setup()Peter Xu2023-02-111-1/+1
| | | | | | | | | | | Since we just dropped the only case where postcopy_preempt_setup() can return an error, it doesn't need a retval anymore because it never fails. Move the preempt check to the caller, preparing it to be used elsewhere to do nothing but as simple as kicking the async connection. Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
* migration: check magic value for deciding the mapping of channelsmanish.mishra2023-02-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Current logic assumes that channel connections on the destination side are always established in the same order as the source and the first one will always be the main channel followed by the multifid or post-copy preemption channel. This may not be always true, as even if a channel has a connection established on the source side it can be in the pending state on the destination side and a newer connection can be established first. Basically causing out of order mapping of channels on the destination side. Currently, all channels except post-copy preempt send a magic number, this patch uses that magic number to decide the type of channel. This logic is applicable only for precopy(multifd) live migration, as mentioned, the post-copy preempt channel does not send any magic number. Also, tls live migrations already does tls handshake before creating other channels, so this issue is not possible with tls, hence this logic is avoided for tls live migrations. This patch uses read peek to check the magic number of channels so that current data/control stream management remains un-effected. Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Suggested-by: Daniel P. Berrange <berrange@redhat.com> Signed-off-by: manish.mishra <manish.mishra@nutanix.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
* migration: Create the postcopy preempt channel asynchronouslyPeter Xu2022-07-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch allows the postcopy preempt channel to be created asynchronously. The benefit is that when the connection is slow, we won't take the BQL (and potentially block all things like QMP) for a long time without releasing. A function postcopy_preempt_wait_channel() is introduced, allowing the migration thread to be able to wait on the channel creation. The channel is always created by the main thread, in which we'll kick a new semaphore to tell the migration thread that the channel has created. We'll need to wait for the new channel in two places: (1) when there's a new postcopy migration that is starting, or (2) when there's a postcopy migration to resume. For the start of migration, we don't need to wait for this channel until when we want to start postcopy, aka, postcopy_start(). We'll fail the migration if we found that the channel creation failed (which should probably not happen at all in 99% of the cases, because the main channel is using the same network topology). For a postcopy recovery, we'll need to wait in postcopy_pause(). In that case if the channel creation failed, we can't fail the migration or we'll crash the VM, instead we keep in PAUSED state, waiting for yet another recovery. Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Manish Mishra <manish.mishra@nutanix.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20220707185509.27311-1-peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
* migration: Postcopy preemption preparation on channel creationPeter Xu2022-07-201-0/+10
| | | | | | | | | | | | | | | | | | | | | | Create a new socket for postcopy to be prepared to send postcopy requested pages via this specific channel, so as to not get blocked by precopy pages. A new thread is also created on dest qemu to receive data from this new channel based on the ram_load_postcopy() routine. The ram_load_postcopy(POSTCOPY) branch and the thread has not started to function, and that'll be done in follow up patches. Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new thread too to make sure it'll be recycled properly. Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20220707185502.27149-1-peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> dgilbert: With Peter's fix to quieten compiler warning on start_migration
* migration: Add postcopy_thread_create()Peter Xu2022-03-021-0/+4
| | | | | | | | | | | | | Postcopy create threads. A common manner is we init a sem and use it to sync with the thread. Namely, we have fault_thread_sem and listen_thread_sem and they're only used for this. Make it a shared infrastructure so it's easier to create yet another thread. Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20220301083925.33483-7-peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
* migration/: fix some comment spelling errorszhaolichang2020-09-171-1/+1
| | | | | | | | | | | I found that there are many spelling errors in the comments of qemu, so I used the spellcheck tool to check the spelling errors and finally found some spelling errors in the migration folder. Signed-off-by: zhaolichang <zhaolichang@huawei.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Message-Id: <20200917075029.313-3-zhaolichang@huawei.com> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
* migration/postcopy: rename postcopy_ram_enable_notify to postcopy_ram_incoming_setupWei Yang2019-10-111-1/+1
| | | | | | | | | | | Function postcopy_ram_incoming_setup and postcopy_ram_incoming_cleanup is a pair. Rename to make it clear for audience. Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Message-Id: <20191010011316.31363-2-richardw.yang@linux.intel.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
* migration/postcopy: allocate tmp_page in setup stageWei Yang2019-10-111-7/+0
| | | | | | | | | | | | | | | | During migration, a tmp page is allocated so that we could place a whole host page during postcopy. Currently the page is allocated during load stage, this is a little bit late. And more important, if we failed to allocate it, the error is not checked properly. Even it is NULL, we would still use it. This patch moves the allocation to setup stage and if failed error message would be printed and caller would notice it. Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
* migration/postcopy: make PostcopyDiscardState a static variableWei Yang2019-08-141-8/+5
| | | | | | | | | | | | | | | | | | | | | | | | | In postcopy-ram.c, we provide three functions to discard certain RAMBlock range: * postcopy_discard_send_init() * postcopy_discard_send_range() * postcopy_discard_send_finish() Currently, we allocate/deallocate PostcopyDiscardState for each RAMBlock on sending discard information to destination. This is not necessary and the same data area could be reused for each RAMBlock. This patch defines PostcopyDiscardState a static variable. By doing so: 1) avoid memory allocation and deallocation to the system 2) avoid potential failure of memory allocation 3) hide some details for their users Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Message-Id: <20190724010721.2146-1-richardw.yang@linux.intel.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
* postcopy: drop ram_pages parameter from postcopy_ram_incoming_init()David Hildenbrand2018-06-271-1/+1
| | | | | | | | | | Not needed. Don't expose last_ram_page(). Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20180620202736.21399-1-david@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
* vhost+postcopy: Wire up POSTCOPY_END notifyDr. David Alan Gilbert2018-03-201-0/+1
| | | | | | | | | | Wire up a call to VHOST_USER_POSTCOPY_END message to the vhost clients right before we ask the listener thread to shutdown. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* postcopy: postcopy_notify_shared_wakeDr. David Alan Gilbert2018-03-201-0/+10
| | | | | | | | | | | | Add a hook to allow a client userfaultfd to be 'woken' when a page arrives, and a walker that calls that hook for relevant clients given a RAMBlock and offset. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* postcopy: helper for waking sharedDr. David Alan Gilbert2018-03-201-0/+10
| | | | | | | | | | | | Provide a helper to send a 'wake' request on a userfaultfd for a shared process. The address in the clients address space is specified together with the RAMBlock it was resolved to. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* vhost+postcopy: Helper to send requests to source for shared pagesDr. David Alan Gilbert2018-03-201-0/+3
| | | | | | | | | | | | Provide a helper to be used by shared waker functions to request shared pages from the source. The last_rb pointer is moved into the incoming state since this helper can update it as well as the main fault thread function. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* vhost+postcopy: Transmit 'listen' to slaveDr. David Alan Gilbert2018-03-201-0/+1
| | | | | | | | | | | Notify the vhost-user slave on reception of the 'postcopy-listen' event from the source. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* postcopy: Allow registering of fd handlerDr. David Alan Gilbert2018-03-201-0/+21
| | | | | | | | | | Allow other userfaultfd's to be registered into the fault thread so that handlers for shared memory can get responses. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' messageDr. David Alan Gilbert2018-03-201-0/+1
| | | | | | | | | | | | | Wire up a notifier to send a VHOST_USER_POSTCOPY_ADVISE message on an incoming advise. Later patches will fill in the behaviour/contents of the message. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* postcopy: Add notifier chainDr. David Alan Gilbert2018-03-201-0/+26
| | | | | | | | | | | | | | | Add a notifier chain for postcopy with a 'reason' flag and an opportunity for a notifier member to return an error. Call it when enabling postcopy. This will initially used to enable devices to declare they're unable to postcopy and later to notify of devices of stages within postcopy. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
* migration: provide postcopy_fault_thread_notify()Peter Xu2018-02-141-0/+2
| | | | | | | | | A general helper to notify the fault thread. Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20180208103132.28452-4-peterx@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
* migration: postcopy_place_page factoring outAlexey Perevalov2017-10-231-2/+2
| | | | | | | | | | | Need to mark copied pages as closer as possible to the place where it tracks down. That will be necessary in futher patch. Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
* migration: pass MigrationIncomingState* into migration check functionsAlexey Perevalov2017-09-221-1/+1
| | | | | | | | | | That tiny refactoring is necessary to be able to set UFFD_FEATURE_THREAD_ID while requesting features, and then to create downtime context in case when kernel supports it. Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
* migration: Move postcopy stuff to postcopy-ram.cJuan Quintela2017-05-171-0/+26
| | | | | | | Yes, we don't have a good place to put that stuff. Signed-off-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
* migration: Move postcopy-ram.h to migration/Juan Quintela2017-05-041-0/+91
It is internal to migration, not intended for other users. Signed-off-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>