bwlp/qemu.git/migration, branch master

migration: Block migration comment or code is wrong

2022-11-21T10:58:10+00:00

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 Reviewed-by: Stefan Hajnoczi

migration: Disable multifd explicitly with compression

2022-11-21T10:58:10+00:00

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 Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela

migration: Disallow postcopy preempt to be used with compress

2022-11-21T10:58:10+00:00

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 Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela

migration: Fix race on qemu_file_shutdown()

2022-11-21T10:58:10+00:00

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 Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela

migration: Fix possible infinite loop of ram save process

2022-11-21T10:58:10+00:00

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 Signed-off-by: Peter Xu Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela

migration/multifd/zero-copy: Create helper function for flushing

2022-11-21T10:56:12+00:00

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 Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela

migration/channel-block: fix return value for qio_channel_block_{readv,writev}

2022-11-21T10:56:12+00:00

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 Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela

reset: allow registering handlers that aren't called by snapshot loading

2022-10-27T10:34:31+00:00

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 Message-id: 20221025004327.568476-2-Jason@zx2c4.com [PMM: updated json doc comment with Markus' text; fixed checkpatch style nit] Reviewed-by: Peter Maydell Signed-off-by: Peter Maydell

migration: add missing coroutine_fn annotations

2022-10-07T10:11:41+00:00

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 Reviewed-by: Juan Quintela Reviewed-by: Stefan Hajnoczi Reviewed-by: Alberto Faria Signed-off-by: Paolo Bonzini Message-Id: <20220922084924.201610-26-pbonzini@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf

Use g_new() & friends where that makes obvious sense

2022-10-03T22:10:11+00:00

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 Reviewed-by: Michael S. Tsirkin Message-Id: <20220923084254.4173111-1-armbru@redhat.com> Signed-off-by: Laurent Vivier