Use the uffd_copy_page, uffd_zero_page and uffd_wakeup helpers
rather than calling ioctl ourselves.
They return -errno on error, and print an error_report themselves.
I think this actually makes postcopy_place_page actually more
consistent in it's callers.
Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240919134626.166183-7-dave@treblig.org
[peterx: fix i386 build]
Signed-off-by: Peter Xu <peterx@redhat.com>
socket_send_channel_create_sync only use was removed by
d0edb8a173 ("migration: Create the postcopy preempt channel asynchronously")
Remove it.
Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240919134626.166183-5-dave@treblig.org
Signed-off-by: Peter Xu <peterx@redhat.com>
The zero-blocks capability was meant to be used along with the block
migration, which has been removed already in commit eef0bae3a7
("migration: Remove block migration").
Setting zero-blocks is currently a noop, but the outright removal of
the capability would cause and error in case some users are still
setting it. Put the capability through the deprecation process.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240919134626.166183-4-dave@treblig.org
Signed-off-by: Peter Xu <peterx@redhat.com>
migrate_zero_blocks is unused since
eef0bae3a7 ("migration: Remove block migration")
Remove it.
Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240919134626.166183-3-dave@treblig.org
Signed-off-by: Peter Xu <peterx@redhat.com>
migrate_cap_set has been unused since
18d154f575 ("migration: Remove 'blk/-b' option from migrate commands")
Remove it.
Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240919134626.166183-2-dave@treblig.org
Signed-off-by: Peter Xu <peterx@redhat.com>
Coverity points out that the current usage of strncpy to write the
ramblock name allows the field to not have an ending '\0' in case
idstr is already not null-terminated (e.g. if it's larger than 256
bytes).
This is currently harmless because the packet->ramblock field is never
touched again on the source side. The destination side reads only up
to the field's size from the stream and forces the last byte to be 0.
We're still open to a programming error in the future in case this
field is ever passed into a function that expects a null-terminated
string.
Change from strncpy to QEMU's pstrcpy, which puts a '\0' at the end of
the string and doesn't fill the extra space with zeros.
(there's no spillage between iterations of fill_packet because after
commit 87bb9e953e ("migration/multifd: Isolate ram pages packet data")
the packet is always zeroed before filling)
Resolves: Coverity CID 1560071
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240919150611.17074-1-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
../migration/ram.c:1873:23: error: ‘dirty’ may be used uninitialized [-Werror=maybe-uninitialized]
When 'block' != NULL, 'dirty' is initialized.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
../migration/dirtyrate.c:186:5: error: ‘records’ may be used uninitialized [-Werror=maybe-uninitialized]
../migration/dirtyrate.c:168:12: error: ‘gen_id’ may be used uninitialized [-Werror=maybe-uninitialized]
../migration/migration.c:2273:5: error: ‘file’ may be used uninitialized [-Werror=maybe-uninitialized]
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Hyman Huang <yong.huang@smartx.com>
This patch is part of a series that moves towards a consistent use of
g_assert_not_reached() rather than an ad hoc mix of different
assertion mechanisms.
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240919044641.386068-31-pierrick.bouvier@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This patch is part of a series that moves towards a consistent use of
g_assert_not_reached() rather than an ad hoc mix of different
assertion mechanisms.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-ID: <20240919044641.386068-14-pierrick.bouvier@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This patch is part of a series that moves towards a consistent use of
g_assert_not_reached() rather than an ad hoc mix of different
assertion mechanisms.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240919044641.386068-5-pierrick.bouvier@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Fix a segmentation fault in multifd when rb->receivedmap is cleared
too early.
After commit 5ef7e26bdb ("migration/multifd: solve zero page causing
multiple page faults"), multifd started using the rb->receivedmap
bitmap, which belongs to ram.c and is initialized and *freed* from the
ram SaveVMHandlers.
Multifd threads are live until migration_incoming_state_destroy(),
which is called after qemu_loadvm_state_cleanup(), leading to a crash
when accessing rb->receivedmap.
process_incoming_migration_co() ...
qemu_loadvm_state() multifd_nocomp_recv()
qemu_loadvm_state_cleanup() ramblock_recv_bitmap_set_offset()
rb->receivedmap = NULL set_bit_atomic(..., rb->receivedmap)
...
migration_incoming_state_destroy()
multifd_recv_cleanup()
multifd_recv_terminate_threads(NULL)
Move the loadvm cleanup into migration_incoming_state_destroy(), after
multifd_recv_cleanup() to ensure multifd threads have already exited
when rb->receivedmap is cleared.
Adjust the postcopy listen thread comment to indicate that we still
want to skip the cpu synchronization.
CC: qemu-stable@nongnu.org
Fixes: 5ef7e26bdb ("migration/multifd: solve zero page causing multiple page faults")
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240917185802.15619-3-farosas@suse.de
[peterx: added comment in migration_incoming_state_destroy()]
Signed-off-by: Peter Xu <peterx@redhat.com>
There are two qemu_loadvm_state_cleanup() calls that were introduced
when qemu_loadvm_state_setup() was still called before loading the
configuration section, so there was state to be cleaned up if the
header checks failed.
However, commit 9e14b84908 ("migration/savevm: load_header before
load_setup") has moved that configuration section part to
qemu_loadvm_state_header() which now happens before
qemu_loadvm_state_setup().
Remove the cleanup calls that are now misplaced.
Note that we didn't use Fixes because it's benign to cleanup() even if
setup() is not invoked. So this patch is not needed for stable, as it
falls into cleanup category.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240917185802.15619-2-farosas@suse.de
[peterx: added last paragraph of commit message]
Signed-off-by: Peter Xu <peterx@redhat.com>
GitHub's CodeQL reports four critical errors which are fixed by this commit:
Unsigned difference expression compared to zero
An expression (u - v > 0) with unsigned values u, v is only false if u == v,
so all changed expressions did not work as expected.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Link: https://lore.kernel.org/r/20240910054138.1458555-1-sw@weilnetz.de
[peterx: Fix mangled email for author]
Signed-off-by: Peter Xu <peterx@redhat.com>
The qatzip series was based on an older commit, it applied cleanly even
though it has conflicts. Neither CI nor myself found the build will break
as it's skipped by default when qatzip library was missing.
Fix the build issues. No need to copy stable as it just landed 9.2.
Cc: Yichen Wang <yichen.wang@bytedance.com>
Cc: Bryan Zhang <bryan.zhang@bytedance.com>
Cc: Hao Xiang <hao.xiang@linux.dev>
Cc: Yuan Liu <yuan1.liu@intel.com>
Fixes: 80484f9459 ("migration: Introduce 'qatzip' compression method")
Link: https://lore.kernel.org/r/20240910210450.3835123-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Adds support for 'qatzip' as an option for the multifd compression
method parameter, and implements using QAT for 'qatzip' compression and
decompression.
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Prasad Pandit <pjp@fedoraproject.org>
Signed-off-by: Bryan Zhang <bryan.zhang@bytedance.com>
Signed-off-by: Hao Xiang <hao.xiang@linux.dev>
Signed-off-by: Yichen Wang <yichen.wang@bytedance.com>
Link: https://lore.kernel.org/r/20240830232722.58272-5-yichen.wang@bytedance.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Add documentation clarifying the usage of the multifd methods. The
general idea is that the client code calls into multifd to trigger
send/recv of data and multifd then calls these hooks back from the
worker threads at opportune moments so the client can process a
portion of the data.
Suggested-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Check that p->iov is indeed always allocated and freed by the
MultiFDMethods hooks.
Suggested-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The send_cleanup() hook should free the p->iov that was allocated at
send_setup(). This was missed because the UADK code is conditional on
the presence of the accelerator, so it's not tested by default.
Fixes: 819dd20636 ("migration/multifd: Add UADK initialization")
Reported-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
As observed by Philippe, the multifd_ram_unfill_packet() function
currently leaves the MultiFDPacket structure with mixed
endianness. This is harmless, but ultimately not very clean.
Stop touching the received packet and do the necessary work using
stack variables instead.
While here tweak the error strings and fix the space before
semicolons. Also remove the "100 times bigger" comment because it's
just one possible explanation for a size mismatch and it doesn't even
match the code.
CC: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The methods are defined at module_init time and don't ever
change. Make them const.
Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
In preparation for adding new payload types to multifd, move most of
the no-compression code into multifd-nocomp.c. Let's try to keep a
semblance of layering by not mixing general multifd control flow with
the details of transmitting pages of ram.
There are still some pieces leftover, namely the p->normal, p->zero,
etc variables that we use for zero page tracking and the packet
allocation which is heavily dependent on the ram code.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Prior to moving the ram code into multifd-nocomp.c, change the code to
register the nocomp ops dynamically so we don't need to have the ops
structure defined in multifd.c.
While here, move the ops struct initialization to the end of the file
to make the next diff cleaner.
Reviewed-by: Prasad Pandit <pjp@fedoraproject.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add the multifd_ prefix to all functions and remove the useless
docstrings.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Separate the multifd sync from flushing the client data to the
channels. These two operations are closely related but not strictly
necessary to be executed together.
The multifd sync is intrinsic to how multifd works. The multiple
channels operate independently and may finish IO out of order in
relation to each other. This applies also between the source and
destination QEMU.
Flushing the data that is left in the client-owned data structures
(e.g. MultiFDPages_t) prior to sync is usually the right thing to do,
but that is particular to how the ram migration is implemented with
several passes over dirty data.
Make these two routines separate, allowing future code to call the
sync by itself if needed. This also allows the usage of
multifd_ram_send to be isolated to ram code.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Multifd currently has a simple scheduling mechanism that distributes
work to the various channels by keeping storage space within each
channel and an extra space that is given to the client. Each time the
client fills the space with data and calls into multifd, that space is
given to the next idle channel and a free storage space is taken from
the channel and given to client for the next iteration.
This means we always need (#multifd_channels + 1) memory slots to
operate multifd.
This is fine, except that the presence of this one extra memory slot
doesn't allow different types of payloads to be processed at the same
time in different channels, i.e. the data type of
multifd_send_state->pages needs to be the same as p->pages.
For each new data type different from MultiFDPage_t that is to be
handled, this logic would need to be duplicated by adding new fields
to multifd_send_state, to the channels and to multifd_send_pages().
Fix this situation by moving the extra slot into the client and using
only the generic type MultiFDSendData in the multifd core.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Skip saving and loading any ram data in the packet in the case of a
SYNC. This fixes a shortcoming of the current code which requires a
reset of the MultiFDPages_t fields right after the previous
pending_job finishes, otherwise the very next job might be a SYNC and
multifd_send_fill_packet() will put the stale values in the packet.
By not calling multifd_ram_fill_packet(), we can stop resetting
MultiFDPages_t in the multifd core and leave that to the client code.
Actually moving the reset function is not yet done because
pages->num==0 is used by the client code to determine whether the
MultiFDPages_t needs to be flushed. The subsequent patches will
replace that with a generic flag that is not dependent on
MultiFDPages_t.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
While we cannot yet disentangle the multifd packet from page data, we
can make the code a bit cleaner by setting the page-related fields in
a separate function.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The total_normal_pages and total_zero_pages elements are used only for
the end tracepoints of the multifd threads. These are not super useful
since they record per-channel numbers and are just the sum of all the
pages that are transmitted per-packet, for which we already have
tracepoints. Remove the totals from the tracing.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
All references to pages are being removed from the multifd worker
threads in order to allow multifd to deal with different payload
types.
multifd_send_zero_page_detect() is called by all multifd migration
paths that deal with pages and is the last spot where zero pages and
normal page amounts are adjusted. Move the pages accounting into that
function.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
We want multifd to be able to handle more types of data than just ram
pages. To start decoupling multifd from pages, replace p->pages
(MultiFDPages_t) with the new type MultiFDSendData that hides the
client payload inside an union.
The general idea here is to isolate functions that *need* to handle
MultiFDPages_t and move them in the future to multifd-ram.c, while
multifd.c will stay with only the core functions that handle
MultiFDSendData/MultiFDRecvData.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
We're about to use MultiFDPages_t from inside the MultiFDSendData
payload union, which means we cannot have pointers to allocated data
inside the pages structure, otherwise we'd lose the reference to that
memory once another payload type touches the union. Move the offset
array into the end of the structure and turn it into a flexible array
member, so it is allocated along with the rest of MultiFDSendData in
the next patches.
Note that other pointers, such as the ramblock pointer are still fine
as long as the storage for them is not owned by the migration code and
can be correctly released at some point.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Add a new data structure to replace p->pages in the multifd
channel. This new structure will hide the multifd payload type behind
an union, so we don't need to add a new field to the channel each time
we want to handle a different data type.
This also allow us to keep multifd_send_pages() as is, without needing
to complicate the pointer switching.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
We want to stop dereferencing 'pages' so it can be replaced by an
opaque pointer in the next patches.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This value never changes and is always the same as page_count. We
don't need a copy of it per-channel plus one in the extra slot. Remove
it.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The MultiFD*Params structures are for per-channel data. Constant
values should not be there because that needlessly wastes cycles and
storage. The page_size and page_count fall into this category so move
them inline in multifd.h.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
I'm about to replace the p->pages pointer with an opaque pointer, so
do a cleanup now to reduce direct accesses to p->page, which makes the
next diffs cleaner.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
In multifd_recv_setup() we allocate (among other things)
* a MultiFDRecvData struct to multifd_recv_state::data
* a MultiFDRecvData struct to each multfd_recv_state->params[i].data
(Then during execution we might swap these pointers around.)
But in multifd_recv_cleanup() we free multifd_recv_state->data
in multifd_recv_cleanup_state() but we don't ever free the
multifd_recv_state->params[i].data. This results in a memory
leak reported by LeakSanitizer:
(cd build/asan && \
ASAN_OPTIONS="fast_unwind_on_malloc=0:strip_path_prefix=/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/../../" \
QTEST_QEMU_BINARY=./qemu-system-x86_64 \
./tests/qtest/migration-test --tap -k -p /x86_64/migration/multifd/file/mapped-ram )
[...]
Direct leak of 72 byte(s) in 3 object(s) allocated from:
#0 0x561cc0afcfd8 in __interceptor_calloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x218efd8) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)
#1 0x7f89d37acc50 in g_malloc0 debian/build/deb/../../../glib/gmem.c:161:13
#2 0x561cc1e9c83c in multifd_recv_setup migration/multifd.c:1606:19
#3 0x561cc1e68618 in migration_ioc_process_incoming migration/migration.c:972:9
#4 0x561cc1e3ac59 in migration_channel_process_incoming migration/channel.c:45:9
#5 0x561cc1e4fa0b in file_accept_incoming_migration migration/file.c:132:5
#6 0x561cc30f2c0c in qio_channel_fd_source_dispatch io/channel-watch.c:84:12
#7 0x7f89d37a3c43 in g_main_dispatch debian/build/deb/../../../glib/gmain.c:3419:28
#8 0x7f89d37a3c43 in g_main_context_dispatch debian/build/deb/../../../glib/gmain.c:4137:7
#9 0x561cc3b21659 in glib_pollfds_poll util/main-loop.c:287:9
#10 0x561cc3b1ff93 in os_host_main_loop_wait util/main-loop.c:310:5
#11 0x561cc3b1fb5c in main_loop_wait util/main-loop.c:589:11
#12 0x561cc1da2917 in qemu_main_loop system/runstate.c:801:9
#13 0x561cc3796c1c in qemu_default_main system/main.c:37:14
#14 0x561cc3796c67 in main system/main.c:48:12
#15 0x7f89d163bd8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#16 0x7f89d163be3f in __libc_start_main csu/../csu/libc-start.c:392:3
#17 0x561cc0a79fa4 in _start (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x210bfa4) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)
Direct leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x561cc0afcfd8 in __interceptor_calloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x218efd8) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)
#1 0x7f89d37acc50 in g_malloc0 debian/build/deb/../../../glib/gmem.c:161:13
#2 0x561cc1e9bed9 in multifd_recv_setup migration/multifd.c:1588:32
#3 0x561cc1e68618 in migration_ioc_process_incoming migration/migration.c:972:9
#4 0x561cc1e3ac59 in migration_channel_process_incoming migration/channel.c:45:9
#5 0x561cc1e4fa0b in file_accept_incoming_migration migration/file.c:132:5
#6 0x561cc30f2c0c in qio_channel_fd_source_dispatch io/channel-watch.c:84:12
#7 0x7f89d37a3c43 in g_main_dispatch debian/build/deb/../../../glib/gmain.c:3419:28
#8 0x7f89d37a3c43 in g_main_context_dispatch debian/build/deb/../../../glib/gmain.c:4137:7
#9 0x561cc3b21659 in glib_pollfds_poll util/main-loop.c:287:9
#10 0x561cc3b1ff93 in os_host_main_loop_wait util/main-loop.c:310:5
#11 0x561cc3b1fb5c in main_loop_wait util/main-loop.c:589:11
#12 0x561cc1da2917 in qemu_main_loop system/runstate.c:801:9
#13 0x561cc3796c1c in qemu_default_main system/main.c:37:14
#14 0x561cc3796c67 in main system/main.c:48:12
#15 0x7f89d163bd8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#16 0x7f89d163be3f in __libc_start_main csu/../csu/libc-start.c:392:3
#17 0x561cc0a79fa4 in _start (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/qemu-system-x86_64+0x210bfa4) (BuildId: be72e086d4e47b172b0a72779972213fd9916466)
SUMMARY: AddressSanitizer: 96 byte(s) leaked in 4 allocation(s).
Free the params[i].data too.
Cc: qemu-stable@nongnu.org
Fixes: d117ed0699 ("migration/multifd: Allow receiving pages without packets")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
An error path missed setting *errp, which can cause a NULL deref.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20240813050638.446172-11-npiggin@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240813202329.1237572-19-alex.bennee@linaro.org>
When a channel fails to create, the code currently just returns. This
is wrong for two reasons:
1) Channel n+1 will not get to initialize it's semaphores, leading to
an assert when terminate_threads tries to post to it:
qemu-system-x86_64: ../util/qemu-thread-posix.c:92:
qemu_mutex_lock_impl: Assertion `mutex->initialized' failed.
2) (theoretical) If channel n-1 already started creation it will
defeat the purpose of the channels_created logic which is in place
to avoid migrate_fd_cleanup() to run while channels are still being
created.
This cannot really happen today because the current failure cases
for multifd_new_send_channel_create() are all synchronous,
resulting from qio_channel_file_new_path() getting a bad
filename. This would hit all channels equally.
But I don't want to set a trap for future people, so have all
channels try to create (even if failing), and only fail after the
channels_created semaphore has been posted.
While here, remove the error_report_err call. There's one already at
migrate_fd_cleanup later on.
Cc: qemu-stable@nongnu.org
Reported-by: Jim Fehlig <jfehlig@suse.com>
Fixes: b7b03eb614 ("migration/multifd: Add outgoing QIOChannelFile support")
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The QIOChannelFile object already has its reference decremented by
g_autoptr. Trying to unref an extra time causes:
ERROR:../qom/object.c:1241:object_unref: assertion failed: (obj->ref > 0)
Fixes: a701c03dec ("migration: Drop reference to QIOChannel if file seeking fails")
Fixes: 6d3279655a ("migration: Fix file migration with fdset")
Reported-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
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>
Destination QEMU can setup incoming ports for two purposes: either a fresh
new incoming migration, in which QEMU will switch to SETUP for channel
establishment, or a paused postcopy migration, in which QEMU will stay in
POSTCOPY_PAUSED until kicking off the RECOVER phase.
Now the state machine worked on dest node for the latter, only because
migrate_set_state() implicitly will become a noop if the current state
check failed. It wasn't clear at all.
Clean it up by providing a helper migration_incoming_state_setup() doing
proper checks over current status. Postcopy-paused will be explicitly
checked now, and then we can bail out for unknown states.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
QEMU uses "int" in most cases even if it stores MigrationStatus. I don't
know why, so let's try to do that right and see what blows up..
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
The postcopy thread names on dest QEMU are slightly confusing, partly I'll
need to blame myself on 36f62f11e4 ("migration: Postcopy preemption
preparation on channel creation"). E.g., "fault-fast" reads like a fast
version of "fault-default", but it's actually the fast version of
"postcopy/listen".
Taking this chance, rename all the migration threads with proper rules.
Considering we only have 15 chars usable, prefix all threads with "mig/",
meanwhile identify src/dst threads properly this time. So now most thread
names will look like "mig/DIR/xxx", where DIR will be "src"/"dst", except
the bg-snapshot thread which doesn't have a direction.
For multifd threads, making them "mig/{src|dst}/{send|recv}_%d".
We used to have "live_migration" thread for a very long time, now it's
called "mig/src/main". We may hope to have "mig/dst/main" soon but not
yet.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Zhijian Li (Fujitsu) <lizhijian@fujitsu.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
We always do the flush when finishing one round of scan, and during
complete() phase we should scan one more round making sure no dirty page
existed. In that case we shouldn't need one explicit FLUSH at the end of
complete(), as when reaching there all pages should have been flushed.
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Tested-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
When multifd is used along with mapped-ram, we can take benefit of a
filesystem that supports the O_DIRECT flag and perform direct I/O in
the multifd threads. This brings a significant performance improvement
because direct-io writes bypass the page cache which would otherwise
be thrashed by the multifd data which is unlikely to be needed again
in a short period of time.
To be able to use a multifd channel opened with O_DIRECT, we must
ensure that a certain aligment is used. Filesystems usually require a
block-size alignment for direct I/O. The way to achieve this is by
enabling the mapped-ram feature, which already aligns its I/O properly
(see MAPPED_RAM_FILE_OFFSET_ALIGNMENT at ram.c).
By setting O_DIRECT on the multifd channels, all writes to the same
file descriptor need to be aligned as well, even the ones that come
from outside multifd, such as the QEMUFile I/O from the main migration
code. This makes it impossible to use the same file descriptor for the
QEMUFile and for the multifd channels. The various flags and metadata
written by the main migration code will always be unaligned by virtue
of their small size. To workaround this issue, we'll require a second
file descriptor to be used exclusively for direct I/O.
The second file descriptor can be obtained by QEMU by re-opening the
migration file (already possible), or by being provided by the user or
management application (support to be added in future patches).
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
