The general expectation is that header files should follow the same
file/path naming scheme as the corresponding source file. There are
various historical exceptions to this practice in QEMU, with one of
the most notable being the include/qapi/qmp/ directory. Most of the
headers there correspond to source files in qobject/.
This patch corrects most of that inconsistency by creating
include/qobject/ and moving the headers for qobject/ there.
This also fixes MAINTAINERS for include/qapi/qmp/dispatch.h:
scripts/get_maintainer.pl now reports "QAPI" instead of "No
maintainers found".
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com> #s390x
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20241118151235.2665921-2-armbru@redhat.com>
[Rebased]
Two small cleanups in the same section of vmstate_save():
- Check vmdesc before the "mixed null/non-null data in array" logic, to
be crystal clear that it's only about the JSON writer, not the vmstate on
its own in the migration stream.
- Since we have is_null variable now, use that to replace a check.
Signed-off-by: Peter Xu <peterx@redhat.com>
Tested-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Link: https://lore.kernel.org/r/20250114230746.3268797-17-peterx@redhat.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Currently, if an array of pointers contains a NULL pointer, that
pointer will be encoded as '0' in the stream. Since the JSON writer
doesn't define a "pointer" type, that '0' will now be an uint8, which
is different from the original type being pointed to, e.g. struct.
(we're further calling uint8 "nullptr", but that's irrelevant to the
issue)
That mixed-type array shouldn't be compressed, otherwise data is lost
as the code currently makes the whole array have the type of the first
element:
css = {NULL, NULL, ..., 0x5555568a7940, NULL};
{"name": "s390_css", "instance_id": 0, "vmsd_name": "s390_css",
"version": 1, "fields": [
...,
{"name": "css", "array_len": 256, "type": "nullptr", "size": 1},
...,
]}
In the above, the valid pointer at position 254 got lost among the
compressed array of nullptr.
While we could disable the array compression when a NULL pointer is
found, the JSON part of the stream still makes part of downtime, so we
should avoid writing unecessary bytes to it.
Keep the array compression in place, but if NULL and non-NULL pointers
are mixed break the array into several type-contiguous pieces :
css = {NULL, NULL, ..., 0x5555568a7940, NULL};
{"name": "s390_css", "instance_id": 0, "vmsd_name": "s390_css",
"version": 1, "fields": [
...,
{"name": "css", "array_len": 254, "type": "nullptr", "size": 1},
{"name": "css", "type": "struct", "struct": {"vmsd_name": "s390_css_img", ... }, "size": 768},
{"name": "css", "type": "nullptr", "size": 1},
...,
]}
Now each type-discontiguous region will become a new JSON entry. The
reader should interpret this as a concatenation of values, all part of
the same field.
Parsing the JSON with analyze-script.py now shows the proper data
being pointed to at the places where the pointer is valid and
"nullptr" where there's NULL:
"s390_css (14)": {
...
"css": [
"nullptr",
"nullptr",
...
"nullptr",
{
"chpids": [
{
"in_use": "0x00",
"type": "0x00",
"is_virtual": "0x00"
},
...
]
},
"nullptr",
}
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20250109185249.23952-7-farosas@suse.de>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
QEMU plays a trick with null pointers inside an array of pointers in a VMSD
field. See 07d4e69147 ("migration/vmstate: fix array of ptr with
nullptrs") for more details on why. The idea makes sense in general, but
it may overlooked the JSON writer where it could write nothing in a
"struct" in the JSON hints section.
We hit some analyze-migration.py issues on s390 recently, showing that some
of the struct field contains nothing, like:
{"name": "css", "array_len": 256, "type": "struct", "struct": {}, "size": 1}
As described in details by Fabiano:
https://lore.kernel.org/r/87pll37cin.fsf@suse.de
It could be that we hit some null pointers there, and JSON was gone when
they're null pointers.
To fix it, instead of hacking around only at VMStateInfo level, do that
from VMStateField level, so that JSON writer can also be involved. In this
case, JSON writer will replace the pointer array (which used to be a
"struct") to be the real representation of the nullptr field.
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20250109185249.23952-6-farosas@suse.de>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
migration/savevm.c contains some calls to vmstate_save() that are
followed by migrate_set_error() if the integer return value indicates an
error. migrate_set_error() requires that the `Error *` object passed to
it is set. Therefore, vmstate_save() is assumed to always set *errp on
error.
Right now, that assumption is not met: vmstate_save_state_v() (called
internally by vmstate_save()) will not set *errp if
vmstate_subsection_save() or vmsd->post_save() fail. Fix that by adding
an *errp parameter to vmstate_subsection_save(), and by generating a
generic error in case post_save() fails (as is already done for
pre_save()).
Without this patch, qemu will crash after vmstate_subsection_save() or
post_save() have failed inside of a vmstate_save() call (unless
migrate_set_error() then happen to discard the new error because
s->error is already set). This happens e.g. when receiving the state
from a virtio-fs back-end (virtiofsd) fails.
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Link: https://lore.kernel.org/r/20241015170437.310358-1-hreitz@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
For both save/load we actually share the logic on deciding whether a field
should exist. Merge the checks into a helper and use it for both save and
load. When doing so, add documentations and reformat the code to make it
much easier to read.
The real benefit here (besides code cleanups) is we add a trace-point for
this; this is a known spot where we can easily break migration
compatibilities between binaries, and this trace point will be critical for
us to identify such issues.
For example, this will be handy when debugging things like:
https://gitlab.com/qemu-project/qemu/-/issues/932
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20230906204722.514474-1-peterx@redhat.com>
A few code paths exist in the source code,where a migration is
marked as failed via MIGRATION_STATUS_FAILED, but the failure happens
outside of migration.c
In such cases, an error_report() call is made, however the current
MigrationState is never updated with the error description, and hence
clients like libvirt never know the actual reason for the failure.
This patch covers such cases outside of migration.c and updates the
error description at the appropriate places.
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Tejus GK <tejus.gk@nutanix.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231003065538.244752-3-tejus.gk@nutanix.com>
Currently, a few code paths exist in the function vmstate_save_state_v,
which ultimately leads to a migration failure. However, an update in the
current MigrationState for the error description is never done.
vmstate.c somehow doesn't seem to allow the use of migrate_set_error due
to some dependencies for unit tests. Hence, this patch introduces a new
function vmstate_save_state_with_err, which will eventually propagate
the error message to savevm.c where a migrate_set_error call can be
eventually done.
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Tejus GK <tejus.gk@nutanix.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231003065538.244752-2-tejus.gk@nutanix.com>
Local variables shadowing other local variables or parameters make the
code needlessly hard to understand. Tracked down with -Wshadow=local.
Clean up: delete inner declarations when they are actually redundant,
else rename variables.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>
Message-ID: <20230921121312.1301864-3-armbru@redhat.com>
We fairly regularly forget VMSTATE_END_OF_LIST markers off descriptions;
given that the current check is only for ->name being NULL, sometimes
we get unlucky and the code apparently works and no one spots the error.
Explicitly add a flag, VMS_END that should be set, and assert it is
set during the traversal.
Note: This can't go in until we update the copy of vmstate.h in slirp.
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
The name 'ftell' gives the misleading impression that the QEMUFile
objects are seekable. This is not the case, as in general we just
have an opaque stream. The users of this method are only interested
in the total bytes processed. This switches to a new name that
reflects the intended usage.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
dgilbert: Wrapped long line
There are no longer any VMStateDescription structs in the tree which
use the load_state_old support for custom handling of incoming
migration from very old QEMU. Remove the mechanism entirely.
This includes removing one stray useless setting of
minimum_version_id_old in a VMStateDescription with no load_state_old
function, which crept in after the global weeding-out of them in
commit 17e3134061.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220215175705.3846411-1-peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Francisco Iglesias <francisco.iglesias@xilinx.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Commit 8118f0950f "migration: Append JSON description of migration
stream" needs a JSON writer. The existing qobject_to_json() wasn't a
good fit, because it requires building a QObject to convert. Instead,
migration got its very own JSON writer, in commit 190c882ce2 "QJSON:
Add JSON writer". It tacitly limits numbers to int64_t, and strings
contents to characters that don't need escaping, unlike
qobject_to_json().
The previous commit factored the JSON writer out of qobject_to_json().
Replace migration's JSON writer by it.
Cc: Juan Quintela <quintela@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-17-armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The "ret" has been assigned in all branches. It didn't need to be
assigned separately.
Clang static code analyzer show warning:
migration/vmstate.c:365:17: warning: Value stored to 'ret' is never read
ret = 0;
^ ~
Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
