Commit Graph

1649 Commits

Author SHA1 Message Date
Juan Quintela
c8df4a7aef migration: Split save_live_pending() into state_pending_*
We split the function into to:

- state_pending_estimate: We estimate the remaining state size without
  stopping the machine.

- state pending_exact: We calculate the exact amount of remaining
  state.

The only "device" that implements different functions for _estimate()
and _exact() is ram.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2023-02-06 19:22:56 +01:00
Juan Quintela
255dc7af7e migration: No save_live_pending() method uses the QEMUFile parameter
So remove it everywhere.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2023-02-06 19:22:56 +01:00
Peter Xu
301d7ffe5f migration: Fix migration crash when target psize larger than host
Commit d9e474ea56 overlooked the case where the target psize is even larger
than the host psize.  One example is Alpha has 8K page size and migration
will start to crash the source QEMU when running Alpha migration on x86.

Fix it by detecting that case and set host start/end just to cover the
single page to be migrated.

This will slightly optimize the common case where host psize equals to
guest psize so we don't even need to do the roundups, but that's trivial.

Cc: qemu-stable@nongnu.org
Reported-by: Thomas Huth <thuth@redhat.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1456
Fixes: d9e474ea56 ("migration: Teach PSS about host page")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2023-02-06 19:22:56 +01:00
Markus Armbruster
27be86351e migration: Move the QMP command from monitor/ to migration/
This moves the command from MAINTAINERS sections "Human Monitor (HMP)"
and "QMP" to "Migration".

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230124121946.1139465-19-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
2023-02-04 07:56:54 +01:00
Markus Armbruster
119f50ce30 migration: Move HMP commands from monitor/ to migration/
This moves these commands from MAINTAINERS sections "Human
Monitor (HMP)" and "QMP" to "Migration".

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230124121946.1139465-18-armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
2023-02-04 07:56:54 +01:00
Markus Armbruster
e2c1c34f13 include/block: Untangle inclusion loops
We have two inclusion loops:

       block/block.h
    -> block/block-global-state.h
    -> block/block-common.h
    -> block/blockjob.h
    -> block/block.h

       block/block.h
    -> block/block-io.h
    -> block/block-common.h
    -> block/blockjob.h
    -> block/block.h

I believe these go back to Emanuele's reorganization of the block API,
merged a few months ago in commit d7e2fe4aac.

Fortunately, breaking them is merely a matter of deleting unnecessary
includes from headers, and adding them back in places where they are
now missing.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221221133551.3967339-2-armbru@redhat.com>
2023-01-20 07:24:28 +01:00
Peter Maydell
928eac9539 Migration patches for 8.0
Hi
 
 This are the patches that I had to drop form the last PULL request because they werent fixes:
 - AVX2 is dropped, intel posted a fix, I have to redo it
 - Fix for out of order channels is out
   Daniel nacked it and I need to redo it
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Merge tag 'next-8.0-pull-request' of https://gitlab.com/juan.quintela/qemu into staging

Migration patches for 8.0

Hi

This are the patches that I had to drop form the last PULL request because they werent fixes:
- AVX2 is dropped, intel posted a fix, I have to redo it
- Fix for out of order channels is out
  Daniel nacked it and I need to redo it

# gpg: Signature made Thu 15 Dec 2022 09:38:29 GMT
# gpg:                using RSA key 1899FF8EDEBF58CCEE034B82F487EF185872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>" [full]
# gpg:                 aka "Juan Quintela <quintela@trasno.org>" [full]
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* tag 'next-8.0-pull-request' of https://gitlab.com/juan.quintela/qemu:
  migration: Drop rs->f
  migration: Remove old preempt code around state maintainance
  migration: Send requested page directly in rp-return thread
  migration: Move last_sent_block into PageSearchStatus
  migration: Make PageSearchStatus part of RAMState
  migration: Add pss_init()
  migration: Introduce pss_channel
  migration: Teach PSS about host page
  migration: Use atomic ops properly for page accountings
  migration: Yield bitmap_mutex properly when sending/sleeping
  migration: Remove RAMState.f references in compression code
  migration: Trivial cleanup save_page_header() on same block check
  migration: Cleanup xbzrle zero page cache update logic
  migration: Add postcopy_preempt_active()
  migration: Take bitmap mutex when completing ram migration
  migration: Export ram_release_page()
  migration: Export ram_transferred_ram()
  multifd: Create page_count fields into both MultiFD{Recv,Send}Params
  multifd: Create page_size fields into both MultiFD{Recv,Send}Params

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2022-12-15 14:52:13 +00:00
Peter Maydell
48804eebd4 Miscellaneous patches for 2022-12-14
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Merge tag 'pull-misc-2022-12-14' of https://repo.or.cz/qemu/armbru into staging

Miscellaneous patches for 2022-12-14

# gpg: Signature made Wed 14 Dec 2022 15:23:02 GMT
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* tag 'pull-misc-2022-12-14' of https://repo.or.cz/qemu/armbru:
  ppc4xx_sdram: Simplify sdram_ddr_size() to return
  block/vmdk: Simplify vmdk_co_create() to return directly
  cleanup: Tweak and re-run return_directly.cocci
  io: Tidy up fat-fingered parameter name
  qapi: Use returned bool to check for failure (again)
  sockets: Use ERRP_GUARD() where obviously appropriate
  qemu-config: Use ERRP_GUARD() where obviously appropriate
  qemu-config: Make config_parse_qdict() return bool
  monitor: Use ERRP_GUARD() in monitor_init()
  monitor: Simplify monitor_fd_param()'s error handling
  error: Move ERRP_GUARD() to the beginning of the function
  error: Drop a few superfluous ERRP_GUARD()
  error: Drop some obviously superfluous error_propagate()
  Drop more useless casts from void * to pointer

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2022-12-15 10:13:46 +00:00
Peter Xu
7f401b8044 migration: Drop rs->f
Now with rs->pss we can already cache channels in pss->pss_channels.  That
pss_channel contains more infromation than rs->f because it's per-channel.
So rs->f could be replaced by rss->pss[RAM_CHANNEL_PRECOPY].pss_channel,
while rs->f itself is a bit vague now.

Note that vanilla postcopy still send pages via pss[RAM_CHANNEL_PRECOPY],
that's slightly confusing but it reflects the reality.

Then, after the replacement we can safely drop rs->f.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
b062106d3a migration: Remove old preempt code around state maintainance
With the new code to send pages in rp-return thread, there's little help to
keep lots of the old code on maintaining the preempt state in migration
thread, because the new way should always be faster..

Then if we'll always send pages in the rp-return thread anyway, we don't
need those logic to maintain preempt state anymore because now we serialize
things using the mutex directly instead of using those fields.

It's very unfortunate to have those code for a short period, but that's
still one intermediate step that we noticed the next bottleneck on the
migration thread.  Now what we can do best is to drop unnecessary code as
long as the new code is stable to reduce the burden.  It's actually a good
thing because the new "sending page in rp-return thread" model is (IMHO)
even cleaner and with better performance.

Remove the old code that was responsible for maintaining preempt states, at
the meantime also remove x-postcopy-preempt-break-huge parameter because
with concurrent sender threads we don't really need to break-huge anymore.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
9358982744 migration: Send requested page directly in rp-return thread
With all the facilities ready, send the requested page directly in the
rp-return thread rather than queuing it in the request queue, if and only
if postcopy preempt is enabled.  It can achieve so because it uses separate
channel for sending urgent pages.  The only shared data is bitmap and it's
protected by the bitmap_mutex.

Note that since we're moving the ownership of the urgent channel from the
migration thread to rp thread it also means the rp thread is responsible
for managing the qemufile, e.g. properly close it when pausing migration
happens.  For this, let migration_release_from_dst_file to cover shutdown
of the urgent channel too, renaming it as migration_release_dst_files() to
better show what it does.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
ec6f3ab9f4 migration: Move last_sent_block into PageSearchStatus
Since we use PageSearchStatus to represent a channel, it makes perfect
sense to keep last_sent_block (aka, leverage RAM_SAVE_FLAG_CONTINUE) to be
per-channel rather than global because each channel can be sending
different pages on ramblocks.

Hence move it from RAMState into PageSearchStatus.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
f166876423 migration: Make PageSearchStatus part of RAMState
We used to allocate PSS structure on the stack for precopy when sending
pages.  Make it static, so as to describe per-channel ram migration status.

Here we declared RAM_CHANNEL_MAX instances, preparing for postcopy to use
it, even though this patch has not yet to start using the 2nd instance.

This should not have any functional change per se, but it already starts to
export PSS information via the RAMState, so that e.g. one PSS channel can
start to reference the other PSS channel.

Always protect PSS access using the same RAMState.bitmap_mutex.  We already
do so, so no code change needed, just some comment update.  Maybe we should
consider renaming bitmap_mutex some day as it's going to be a more commonly
and big mutex we use for ram states, but just leave it for later.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
ebd88a4973 migration: Add pss_init()
Helper to init PSS structures.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
61717ea9d2 migration: Introduce pss_channel
Introduce pss_channel for PageSearchStatus, define it as "the migration
channel to be used to transfer this host page".

We used to have rs->f, which is a mirror to MigrationState.to_dst_file.

After postcopy preempt initial version, rs->f can be dynamically changed
depending on which channel we want to use.

But that later work still doesn't grant full concurrency of sending pages
in e.g. different threads, because rs->f can either be the PRECOPY channel
or POSTCOPY channel.  This needs to be per-thread too.

PageSearchStatus is actually a good piece of struct which we can leverage
if we want to have multiple threads sending pages.  Sending a single guest
page may not make sense, so we make the granule to be "host page", and in
the PSS structure we allow specify a QEMUFile* to migrate a specific host
page.  Then we open the possibility to specify different channels in
different threads with different PSS structures.

The PSS prefix can be slightly misleading here because e.g. for the
upcoming usage of postcopy channel/thread it's not "searching" (or,
scanning) at all but sending the explicit page that was requested.  However
since PSS existed for some years keep it as-is until someone complains.

This patch mostly (simply) replace rs->f with pss->pss_channel only. No
functional change intended for this patch yet.  But it does prepare to
finally drop rs->f, and make ram_save_guest_page() thread safe.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
d9e474ea56 migration: Teach PSS about host page
Migration code has a lot to do with host pages.  Teaching PSS core about
the idea of host page helps a lot and makes the code clean.  Meanwhile,
this prepares for the future changes that can leverage the new PSS helpers
that this patch introduces to send host page in another thread.

Three more fields are introduced for this:

  (1) host_page_sending: this is set to true when QEMU is sending a host
      page, false otherwise.

  (2) host_page_{start|end}: these point to the start/end of host page
      we're sending, and it's only valid when host_page_sending==true.

For example, when we look up the next dirty page on the ramblock, with
host_page_sending==true, we'll not try to look for anything beyond the
current host page boundary.  This can be slightly efficient than current
code because currently we'll set pss->page to next dirty bit (which can be
over current host page boundary) and reset it to host page boundary if we
found it goes beyond that.

With above, we can easily make migration_bitmap_find_dirty() self contained
by updating pss->page properly.  rs* parameter is removed because it's not
even used in old code.

When sending a host page, we should use the pss helpers like this:

  - pss_host_page_prepare(pss): called before sending host page
  - pss_within_range(pss): whether we're still working on the cur host page?
  - pss_host_page_finish(pss): called after sending a host page

Then we can use ram_save_target_page() to save one small page.

Currently ram_save_host_page() is still the only user. If there'll be
another function to send host page (e.g. in return path thread) in the
future, it should follow the same style.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
23b7576d78 migration: Use atomic ops properly for page accountings
To prepare for thread-safety on page accountings, at least below counters
need to be accessed only atomically, they are:

        ram_counters.transferred
        ram_counters.duplicate
        ram_counters.normal
        ram_counters.postcopy_bytes

There are a lot of other counters but they won't be accessed outside
migration thread, then they're still safe to be accessed without atomic
ops.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
f3321554ef migration: Yield bitmap_mutex properly when sending/sleeping
Don't take the bitmap mutex when sending pages, or when being throttled by
migration_rate_limit() (which is a bit tricky to call it here in ram code,
but seems still helpful).

It prepares for the possibility of concurrently sending pages in >1 threads
using the function ram_save_host_page() because all threads may need the
bitmap_mutex to operate on bitmaps, so that either sendmsg() or any kind of
qemu_sem_wait() blocking for one thread will not block the other from
progressing.

Signed-off-by: Peter Xu <peterx@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>
2022-12-15 10:30:37 +01:00
Peter Xu
eaa238ab31 migration: Remove RAMState.f references in compression code
Removing referencing to RAMState.f in compress_page_with_multi_thread() and
flush_compressed_data().

Compression code by default isn't compatible with having >1 channels (or it
won't currently know which channel to flush the compressed data), so to
make it simple we always flush on the default to_dst_file port until
someone wants to add >1 ports support, as rs->f right now can really
change (after postcopy preempt is introduced).

There should be no functional change at all after patch applied, since as
long as rs->f referenced in compression code, it must be to_dst_file.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
10661f1180 migration: Trivial cleanup save_page_header() on same block check
The 2nd check on RAM_SAVE_FLAG_CONTINUE is a bit redundant.  Use a boolean
to be clearer.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
ef5c3d1391 migration: Cleanup xbzrle zero page cache update logic
The major change is to replace "!save_page_use_compression()" with
"xbzrle_enabled" to make it clear.

Reasonings:

(1) When compression enabled, "!save_page_use_compression()" is exactly the
    same as checking "xbzrle_enabled".

(2) When compression disabled, "!save_page_use_compression()" always return
    true.  We used to try calling the xbzrle code, but after this change we
    won't, and we shouldn't need to.

Since at it, drop the xbzrle_enabled check in xbzrle_cache_zero_page()
because with this change it's not needed anymore.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
20123ee1de migration: Add postcopy_preempt_active()
Add the helper to show that postcopy preempt enabled, meanwhile active.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-12-15 10:30:37 +01:00
Peter Xu
c13221b56f migration: Take bitmap mutex when completing ram migration
Any call to ram_find_and_save_block() needs to take the bitmap mutex.  We
used to not take it for most of ram_save_complete() because we thought
we're the only one left using the bitmap, but it's not true after the
preempt full patchset applied, since the return path can be taking it too.

Signed-off-by: Peter Xu <peterx@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>
2022-12-15 10:30:37 +01:00
Juan Quintela
a4dbaf8eed migration: Export ram_release_page()
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>
2022-12-15 10:30:37 +01:00
Juan Quintela
26a2606916 migration: Export ram_transferred_ram()
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>
2022-12-15 10:30:37 +01:00
Juan Quintela
d6f45eba2b multifd: Create page_count fields into both MultiFD{Recv,Send}Params
We were recalculating it left and right.  We plan to change that
values on next patches.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>
2022-12-15 10:30:37 +01:00
Juan Quintela
ddec20f858 multifd: Create page_size fields into both MultiFD{Recv,Send}Params
We were calling qemu_target_page_size() left and right.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Leonardo Bras <leobras@redhat.com>
2022-12-15 10:30:37 +01:00
Markus Armbruster
720a252c26 qapi migration: Elide redundant has_FOO in generated C
The has_FOO for pointer-valued FOO are redundant, except for arrays.
They are also a nuisance to work with.  Recent commit "qapi: Start to
elide redundant has_FOO in generated C" provided the means to elide
them step by step.  This is the step for qapi/migration.json.

Said commit explains the transformation in more detail.  The invariant
violations mentioned there do not occur here.

Cc: Juan Quintela <quintela@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20221104160712.3005652-17-armbru@redhat.com>
2022-12-14 20:04:47 +01:00
Markus Armbruster
66997c42e0 cleanup: Tweak and re-run return_directly.cocci
Tweak the semantic patch to drop redundant parenthesis around the
return expression.

Coccinelle drops a comment in hw/rdma/vmw/pvrdma_cmd.c; restored
manually.

Coccinelle messes up vmdk_co_create(), not sure why.  Change dropped,
will be done manually in the next commit.

Line breaks in target/avr/cpu.h and hw/rdma/vmw/pvrdma_cmd.c tidied up
manually.

Whitespace in tools/virtiofsd/fuse_lowlevel.c tidied up manually.

checkpatch.pl complains "return of an errno should typically be -ve"
two times for hw/9pfs/9p-synth.c.  Preexisting, the patch merely makes
it visible to checkpatch.pl.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221122134917.1217307-2-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-12-14 16:19:35 +01:00
Juan Quintela
b5280437a7 migration: Block migration comment or code is wrong
And it appears that what is wrong is the code. During bulk stage we
need to make sure that some block is dirty, but no games with
max_size at all.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-11-21 11:58:10 +01:00
Peter Xu
6f39c90b86 migration: Disable multifd explicitly with compression
Multifd thread model does not work for compression, explicitly disable it.

Note that previuosly even we can enable both of them, nothing will go
wrong, because the compression code has higher priority so multifd feature
will just be ignored.  Now we'll fail even earlier at config time so the
user should be aware of the consequence better.

Note that there can be a slight chance of breaking existing users, but
let's assume they're not majority and not serious users, or they should
have found that multifd is not working already.

With that, we can safely drop the check in ram_save_target_page() for using
multifd, because when multifd=on then compression=off, then the removed
check on save_page_use_compression() will also always return false too.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-11-21 11:58:10 +01:00
Peter Xu
afed4273b5 migration: Disallow postcopy preempt to be used with compress
The preempt mode requires the capability to assign channel for each of the
page, while the compression logic will currently assign pages to different
compress thread/local-channel so potentially they're incompatible.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-11-21 11:58:10 +01:00
Peter Xu
f5816b5c86 migration: Fix race on qemu_file_shutdown()
In qemu_file_shutdown(), there's a possible race if with current order of
operation.  There're two major things to do:

  (1) Do real shutdown() (e.g. shutdown() syscall on socket)
  (2) Update qemufile's last_error

We must do (2) before (1) otherwise there can be a race condition like:

      page receiver                     other thread
      -------------                     ------------
      qemu_get_buffer()
                                        do shutdown()
        returns 0 (buffer all zero)
        (meanwhile we didn't check this retcode)
      try to detect IO error
        last_error==NULL, IO okay
      install ALL-ZERO page
                                        set last_error
      --> guest crash!

To fix this, we can also check retval of qemu_get_buffer(), but not all
APIs can be properly checked and ultimately we still need to go back to
qemu_file_get_error().  E.g. qemu_get_byte() doesn't return error.

Maybe some day a rework of qemufile API is really needed, but for now keep
using qemu_file_get_error() and fix it by not allowing that race condition
to happen.  Here shutdown() is indeed special because the last_error was
emulated.  For real -EIO errors it'll always be set when e.g. sendmsg()
error triggers so we won't miss those ones, only shutdown() is a bit tricky
here.

Cc: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-11-21 11:58:10 +01:00
Peter Xu
4934a5dd7c migration: Fix possible infinite loop of ram save process
When starting ram saving procedure (especially at the completion phase),
always set last_seen_block to non-NULL to make sure we can always correctly
detect the case where "we've migrated all the dirty pages".

Then we'll guarantee both last_seen_block and pss.block will be valid
always before the loop starts.

See the comment in the code for some details.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-11-21 11:58:10 +01:00
Leonardo Bras
4cc47b4395 migration/multifd/zero-copy: Create helper function for flushing
Move flushing code from multifd_send_sync_main() to a new helper, and call
it in multifd_send_sync_main().

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-11-21 11:56:12 +01:00
Fiona Ebner
a216ec85b7 migration/channel-block: fix return value for qio_channel_block_{readv,writev}
in the error case. The documentation in include/io/channel.h states
that -1 or QIO_CHANNEL_ERR_BLOCK should be returned upon error. Simply
passing along the return value from the bdrv-functions has the
potential to confuse the call sides. Non-blocking mode is not
implemented currently, so -1 it is.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2022-11-21 11:56:12 +01:00
Jason A. Donenfeld
7966d70f6f reset: allow registering handlers that aren't called by snapshot loading
Snapshot loading only expects to call deterministic handlers, not
non-deterministic ones. So introduce a way of registering handlers that
won't be called when reseting for snapshots.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Message-id: 20221025004327.568476-2-Jason@zx2c4.com
[PMM: updated json doc comment with Markus' text; fixed
 checkpatch style nit]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2022-10-27 11:34:31 +01:00
Marc-André Lureau
38e8f9af08 migration: add missing coroutine_fn annotations
Callers of coroutine_fn must be coroutine_fn themselves, or the call
must be within "if (qemu_in_coroutine())".  Apply coroutine_fn to
functions where this holds.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220922084924.201610-26-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-10-07 12:11:41 +02:00
Markus Armbruster
c5e8d51824 Use g_new() & friends where that makes obvious sense
g_new(T, n) is neater than g_malloc(sizeof(T) * n).  It's also safer,
for two reasons.  One, it catches multiplication overflowing size_t.
Two, it returns T * rather than void *, which lets the compiler catch
more type errors.

This commit only touches allocations with size arguments of the form
sizeof(T).

Patch created mechanically with:

    $ spatch --in-place --sp-file scripts/coccinelle/use-g_new-etc.cocci \
	     --macro-file scripts/cocci-macro-file.h FILES...

The previous iteration was commit a95942b50c.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20220923084254.4173111-1-armbru@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2022-10-04 00:10:11 +02:00
Peter Maydell
4bcb7de072 migration: Define BLK_MIG_BLOCK_SIZE as unsigned long long
When we use BLK_MIG_BLOCK_SIZE in expressions like
block_mig_state.submitted * BLK_MIG_BLOCK_SIZE, this multiplication
is done as 32 bits, because both operands are 32 bits.  Coverity
complains about possible overflows because we then accumulate that
into a 64 bit variable.

Define BLK_MIG_BLOCK_SIZE as unsigned long long using the ULL suffix.
The only two current uses of it with this problem are both in
block_save_pending(), so we could just cast to uint64_t there, but
using the ULL suffix is simpler and ensures that we don't
accidentally introduce new variants of the same issue in future.

Resolves: Coverity CID 1487136, 1487175
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220721115207.729615-3-peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-08-02 16:46:52 +01:00
Peter Maydell
ead34f64f9 migration: Assert that migrate_multifd_compression() returns an in-range value
Coverity complains that when we use the return value from
migrate_multifd_compression() as an array index:
  multifd_recv_state->ops = multifd_ops[migrate_multifd_compression()];

that this might overrun the array (which is declared to have size
MULTIFD_COMPRESSION__MAX).  This is because the function return type
is MultiFDCompression, which is an autogenerated enum.  The code
generator includes the "one greater than the maximum possible value"
MULTIFD_COMPRESSION__MAX in the enum, even though this is not
actually a valid value for the enum, and this makes Coverity think
that migrate_multifd_compression() could return that __MAX value and
index off the end of the array.

Suppress the Coverity error by asserting that the value we're going
to return is within range.

Resolves: Coverity CID 1487239, 1487254
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220721115207.729615-2-peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-08-02 16:46:52 +01:00
Thomas Huth
777f53c759 Revert "migration: Simplify unqueue_page()"
This reverts commit cfd66f30fb.

The simplification of unqueue_page() introduced a bug that sometimes
breaks migration on s390x hosts.

The problem is not fully understood yet, but since we are already in
the freeze for QEMU 7.1 and we need something working there, let's
revert this patch for the upcoming release. The optimization can be
redone later again in a proper way if necessary.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2099934
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220802061949.331576-1-thuth@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-08-02 16:46:52 +01:00
Leonardo Bras
df67aa3e61 migration: add remaining params->has_* = true in migration_instance_init()
Some of params->has_* = true are missing in migration_instance_init, this
causes migrate_params_check() to skip some tests, allowing some
unsupported scenarios.

Fix this by adding all missing params->has_* = true in
migration_instance_init().

Fixes: 69ef1f36b0 ("migration: define 'tls-creds' and 'tls-hostname' migration parameters")
Fixes: 1d58872a91 ("migration: do not wait for free thread")
Fixes: d2f1d29b95 ("migration: add support for a "tls-authz" migration parameter")
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220726010235.342927-1-leobras@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-08-02 16:46:52 +01:00
Leonardo Bras
90eb69e4f1 migration: Avoid false-positive on non-supported scenarios for zero-copy-send
Migration with zero-copy-send currently has it's limitations, as it can't
be used with TLS nor any kind of compression. In such scenarios, it should
output errors during parameter / capability setting.

But currently there are some ways of setting this not-supported scenarios
without printing the error message:

!) For 'compression' capability, it works by enabling it together with
zero-copy-send. This happens because the validity test for zero-copy uses
the helper unction migrate_use_compression(), which check for compression
presence in s->enabled_capabilities[MIGRATION_CAPABILITY_COMPRESS].

The point here is: the validity test happens before the capability gets
enabled. If all of them get enabled together, this test will not return
error.

In order to fix that, replace migrate_use_compression() by directly testing
the cap_list parameter migrate_caps_check().

2) For features enabled by parameters such as TLS & 'multifd_compression',
there was also a possibility of setting non-supported scenarios: setting
zero-copy-send first, then setting the unsupported parameter.

In order to fix that, also add a check for parameters conflicting with
zero-copy-send on migrate_params_check().

3) XBZRLE is also a compression capability, so it makes sense to also add
it to the list of capabilities which are not supported with zero-copy-send.

Fixes: 1abaec9a1b ("migration: Change zero_copy_send from migration parameter to migration capability")
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Message-Id: <20220719122345.253713-1-leobras@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-07-20 12:15:09 +01:00
Juan Quintela
4a8f19c95c multifd: Document the locking of MultiFD{Send/Recv}Params
Reorder the structures so we can know if the fields are:
- Read only
- Their own locking (i.e. sems)
- Protected by 'mutex'
- Only for the multifd channel

Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20220531104318.7494-2-quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  dgilbert: Typo fixes from Chen Zhang
2022-07-20 12:15:09 +01:00
Leonardo Bras
d59c40cc48 migration/multifd: Report to user when zerocopy not working
Some errors, like the lack of Scatter-Gather support by the network
interface(NETIF_F_SG) may cause sendmsg(...,MSG_ZEROCOPY) to fail on using
zero-copy, which causes it to fall back to the default copying mechanism.

After each full dirty-bitmap scan there should be a zero-copy flush
happening, which checks for errors each of the previous calls to
sendmsg(...,MSG_ZEROCOPY). If all of them failed to use zero-copy, then
increment dirty_sync_missed_zero_copy migration stat to let the user know
about it.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220711211112.18951-4-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-07-20 12:15:09 +01:00
Leonardo Bras
cf20c89733 Add dirty-sync-missed-zero-copy migration stat
Signed-off-by: Leonardo Bras <leobras@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220711211112.18951-3-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-07-20 12:15:09 +01:00
Daniel P. Berrangé
5f87072e95 migration: remove unreachable code after reading data
The code calls qio_channel_read() in a loop when it reports
QIO_CHANNEL_ERR_BLOCK. This code is reported when errno==EAGAIN.

As such the later block of code will always hit the 'errno != EAGAIN'
condition, making the final 'else' unreachable.

Fixes: Coverity CID 1490203
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220627135318.156121-1-berrange@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-07-20 12:15:09 +01:00
Peter Xu
82b54ef4c1 migration: Respect postcopy request order in preemption mode
With preemption mode on, when we see a postcopy request that was requesting
for exactly the page that we have preempted before (so we've partially sent
the page already via PRECOPY channel and it got preempted by another
postcopy request), currently we drop the request so that after all the
other postcopy requests are serviced then we'll go back to precopy stream
and start to handle that.

We dropped the request because we can't send it via postcopy channel since
the precopy channel already contains partial of the data, and we can only
send a huge page via one channel as a whole.  We can't split a huge page
into two channels.

That's a very corner case and that works, but there's a change on the order
of postcopy requests that we handle since we're postponing this (unlucky)
postcopy request to be later than the other queued postcopy requests.  The
problem is there's a possibility that when the guest was very busy, the
postcopy queue can be always non-empty, it means this dropped request will
never be handled until the end of postcopy migration. So, there's a chance
that there's one dest QEMU vcpu thread waiting for a page fault for an
extremely long time just because it's unluckily accessing the specific page
that was preempted before.

The worst case time it needs can be as long as the whole postcopy migration
procedure.  It's extremely unlikely to happen, but when it happens it's not
good.

The root cause of this problem is because we treat pss->postcopy_requested
variable as with two meanings bound together, as the variable shows:

  1. Whether this page request is urgent, and,
  2. Which channel we should use for this page request.

With the old code, when we set postcopy_requested it means either both (1)
and (2) are true, or both (1) and (2) are false.  We can never have (1)
and (2) to have different values.

However it doesn't necessarily need to be like that.  It's very legal that
there's one request that has (1) very high urgency, but (2) we'd like to
use the precopy channel.  Just like the corner case we were discussing
above.

To differenciate the two meanings better, introduce a new field called
postcopy_target_channel, showing which channel we should use for this page
request, so as to cover the old meaning (2) only.  Then we leave the
postcopy_requested variable to stand only for meaning (1), which is the
urgency of this page request.

With this change, we can easily boost priority of a preempted precopy page
as long as we know that page is also requested as a postcopy page.  So with
the new approach in get_queued_page() instead of dropping that request, we
send it right away with the precopy channel so we get back the ordering of
the page faults just like how they're requested on dest.

Reported-by: Manish Mishra <manish.mishra@nutanix.com>
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: <20220707185520.27583-1-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-07-20 12:15:09 +01:00
Peter Xu
f0afaf6ce4 migration: Enable TLS for preempt channel
This patch is based on the async preempt channel creation.  It continues
wiring up the new channel with TLS handshake to destionation when enabled.

Note that only the src QEMU needs such operation; the dest QEMU does not
need any change for TLS support due to the fact that all channels are
established synchronously there, so all the TLS magic is already properly
handled by migration_tls_channel_process_incoming().

Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220707185518.27529-1-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-07-20 12:15:09 +01:00