Make VMS_ARRAY_OF_POINTER cope with null pointers. Previously the
reward for trying to migrate an array with some null pointers in it was
an illegal memory access, that is a swift and painless death of the
process. Let's make vmstate cope with this scenario.
The general approach is, when we encounter a null pointer (element),
instead of following the pointer to save/load the data behind it, we
save/load a placeholder. This way we can detect if we expected a null
pointer at the load side but not null data was saved instead.
Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Guenther Hutzl <hutzl@linux.vnet.ibm.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170222160119.52771-4-pasic@linux.vnet.ibm.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Currently vmstate_base_addr does several things: it pinpoints the field
within the struct, possibly allocates memory and possibly does the first
pointer dereference. Obviously allocation is needed only for load.
Let us split up the functionality in vmstate_base_addr and move the
address manipulations (that is everything but the allocation logic) to
load and save so it becomes more obvious what is actually going on. Like
this all the address calculations (and the handling of the flags
controlling these) is in one place and the sequence is more obvious.
The newly introduced function vmstate_handle_alloc also fixes the
allocation for the unused VMS_VBUFFER|VMS_MULTIPLY|VMS_ALLOC scenario
and is substantially simpler than the original vmstate_base_addr.
In load and save some asserts are added so it's easier to debug
situations where we would end up with a null pointer dereference.
Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170222160119.52771-3-pasic@linux.vnet.ibm.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The vmstate_(load|save)_state start out with an a void *opaque pointing
to some struct, and manipulate one or more elements of one field within
that struct.
First the field within the struct is pinpointed as opaque + offset, then
if this is a pointer the pointer is dereferenced to obtain a pointer to
the first element of the vmstate field. Pointers to further elements if
any are calculated as first_element + i * element_size (where i is the
zero based index of the element in question).
Currently base_addr and addr is used as a variable name for the pointer
to the first element and the pointer to the current element being
processed. This is suboptimal because base_addr is somewhat
counter-intuitive (because obtained as base + offset) and both base_addr
and addr not very descriptive (that we have a pointer should be clear
from the fact that it is declared as a pointer).
Let make things easier to understand by renaming base_addr to first_elem
and addr to curr_elem. This has the additional benefit of harmonizing
with other names within the scope (n_elems, vmstate_n_elems).
Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20170222160119.52771-2-pasic@linux.vnet.ibm.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
VMSTATE_WITH_TMP is for handling structures where some calculation
or rearrangement of the data needs to be performed before the data
hits the wire.
For example, where the value on the wire is an offset from a
non-migrated base, but the data in the structure is the actual pointer.
To use it, a temporary type is created and a vmsd used on that type.
The first element of the type must be 'parent' a pointer back to the
type of the main structure. VMSTATE_WITH_TMP takes care of allocating
and freeing the temporary before running the child vmsd.
The post_load/pre_save on the child vmsd can copy things from the parent
to the temporary using the parent pointer and do any other calculations
needed; it can then use normal VMSD entries to do the actual data
storage without having to fiddle around with qemu_get_*/qemu_put_*
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20170203160651.19917-3-dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The member VMStateField.start is used for two things, partial data
migration for VBUFFER data (basically provide migration for a
sub-buffer) and for locating next in QTAILQ.
The implementation of the VBUFFER feature is broken when VMSTATE_ALLOC
is used. This however goes unnoticed because actually partial migration
for VBUFFER is not used at all.
Let's consolidate the usage of VMStateField.start by removing support
for partial migration for VBUFFER.
Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Message-Id: <20170203175217.45562-1-pasic@linux.vnet.ibm.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Add some tracing to vmstate_subsection_save and vmstate_save_state
to help in debugging when you're not sure if a conditional piece
of data is being saved.
In vmstate_subsection_save I renamed the inner vmsd to avoid the aliasing
and be able to print both names.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20161212125838.14425-1-dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Added error_report where version_ids do not match in vmstate_load_state.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Jianjun Duan <duanj@linux.vnet.ibm.com>
Message-Id: <1484852453-12728-5-git-send-email-duanj@linux.vnet.ibm.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Currently we cannot directly transfer a QTAILQ instance because of the
limitation in the migration code. Here we introduce an approach to
transfer such structures. We created VMStateInfo vmstate_info_qtailq
for QTAILQ. Similar VMStateInfo can be created for other data structures
such as list.
When a QTAILQ is migrated from source to target, it is appended to the
corresponding QTAILQ structure, which is assumed to have been properly
initialized.
This approach will be used to transfer pending_events and ccs_list in spapr
state.
We also create some macros in qemu/queue.h to access a QTAILQ using pointer
arithmetic. This ensures that we do not depend on the implementation
details about QTAILQ in the migration code.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Jianjun Duan <duanj@linux.vnet.ibm.com>
Message-Id: <1484852453-12728-3-git-send-email-duanj@linux.vnet.ibm.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Current migration code cannot handle some data structures such as
QTAILQ in qemu/queue.h. Here we extend the signatures of put/get
in VMStateInfo so that customized handling is supported. put now
will return int type.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Jianjun Duan <duanj@linux.vnet.ibm.com>
Message-Id: <1484852453-12728-2-git-send-email-duanj@linux.vnet.ibm.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Report the values when a comparison fails; together with
the previous patch that prints the device and field names
this should give a good idea of why loading the migration failed.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
When a field fails to load (typically due to a limit
check, or a call to a get/put) report the device and field
to give an indication of the cause.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
A couple of improvements to tracing that have come out of helping
people with migration problems:
* vmstate_n_elems trace the count/name - for when you have problems
getting array counts right
* vmstate_subsection_load_bad - add the idstr, for when you receive a
subsection you weren't expecting.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1465896986-16132-1-git-send-email-dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Type QJSON lets you build JSON text. Its interface mirrors (a subset
of) abstract JSON syntax.
QAPI output visitors also produce JSON text. They assert their
preconditions and invariants, and therefore abort on incorrect use.
Contrastingly, QJSON does *not* detect incorrect use. It happily
produces invalid JSON then. This is what migration wants.
QJSON was designed for migration, and migration is its only user.
Move it to migration/ for proper coverage by MAINTAINERS, and to deter
accidental use outside migration.
[Pointed out by Eric: QJSON was added in commits 0457d07..b174257
-- Amit]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <1462380558-2030-2-git-send-email-armbru@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1453832250-766-2-git-send-email-peter.maydell@linaro.org
This allows to send a partial array where the size is another
structure field multiplied by a constant.
Signed-off-by: Juan Quintela <quintela@redhat.com>
[PMM: updated to current master]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Add vmstate support for migrating arrays of CPU_DoubleU via
VMSTATE_CPUDOUBLE_ARRAY.
Signed-off-by: Juan Quintela <quintela@redhat.com>
[PMM: rebased, since files have all moved since 2012;
added VMSTATE_CPUDOUBLE_ARRAY_V for consistency with FLOAT64]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
To make sections optional, we need to do it at the beggining of the code.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
qemu_peek_buffer currently copies the data it reads into a buffer,
however a future patch wants access to the buffer without the copy,
hence rework to remove the copy to the layer above.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
We create optional sections with this patch. But we already have
optional subsections. Instead of having two mechanism that do the
same, we can just generalize it.
For subsections we just change:
- Add a needed function to VMStateDescription
- Remove VMStateSubsection (after removal of the needed function
it is just a VMStateDescription)
- Adjust the whole tree, moving the needed function to the corresponding
VMStateDescription
Signed-off-by: Juan Quintela <quintela@redhat.com>
One of the annoyances of the current migration format is the fact that
it's not self-describing. In fact, it's not properly describing at all.
Some code randomly scattered throughout QEMU elaborates roughly how to
read and write a stream of bytes.
We discussed an idea during KVM Forum 2013 to add a JSON description of
the migration protocol itself to the migration stream. This patch
adds a section after the VM_END migration end marker that contains
description data on what the device sections of the stream are composed of.
This approach is backwards compatible with any QEMU version reading the
stream, because QEMU just stops reading after the VM_END marker and ignores
any data following it.
With an additional external program this allows us to decipher the
contents of any migration stream and hopefully make migration bugs easier
to track down.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Mostly on the load side, so that when we get a complaint about
a migration failure we can figure out what it didn't like.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Convert a bunch of fprintfs to error_reports
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
The migration code now occupies a fair chunk of the top level .c
files, it seems time to give it it's own directory.
I've not touched:
arch_init.c - that's mostly RAM migration but has a few random other
bits
savevm.c - because it's built target specific
This is purely a code move; no code has changed.
- it fails checkpatch because of old violations, it feels safer
to keep this as purely a move and fix those at some mythical future
date.
The xbzrle and vmstate tests are now only run for softmmu builds
since they require files in the migrate/ directory which is only built
for softmmu.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
