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migration: migrate QTAILQ

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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>
This commit is contained in:
Jianjun Duan 2017-01-19 11:00:51 -08:00 • committed by Dr. David Alan Gilbert
parent 2c21ee769e
commit 94869d5c52
4 changed files with 153 additions and 0 deletions
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20
include/migration/vmstate.h
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@ -260,6 +260,7 @@ extern const VMStateInfo vmstate_info_timer;
extern const VMStateInfo vmstate_info_buffer;
extern const VMStateInfo vmstate_info_unused_buffer;
extern const VMStateInfo vmstate_info_bitmap;
extern const VMStateInfo vmstate_info_qtailq;
#define type_check_2darray(t1,t2,n,m) ((t1(*)[n][m])0 - (t2*)0)
#define type_check_array(t1,t2,n) ((t1(*)[n])0 - (t2*)0)
@ -671,6 +672,25 @@ extern const VMStateInfo vmstate_info_bitmap;
.offset = offsetof(_state, _field), \
}
/* For migrating a QTAILQ.
* Target QTAILQ needs be properly initialized.
* _type: type of QTAILQ element
* _next: name of QTAILQ entry field in QTAILQ element
* _vmsd: VMSD for QTAILQ element
* size: size of QTAILQ element
* start: offset of QTAILQ entry in QTAILQ element
*/
#define VMSTATE_QTAILQ_V(_field, _state, _version, _vmsd, _type, _next) \
{ \
.name = (stringify(_field)), \
.version_id = (_version), \
.vmsd = &(_vmsd), \
.size = sizeof(_type), \
.info = &vmstate_info_qtailq, \
.offset = offsetof(_state, _field), \
.start = offsetof(_type, _next), \
}
/* _f : field name
_f_n : num of elements field_name
_n : num of elements