Reduce number of allocations sending memory state.

Changes since v1:
- add commit to cache up to 4 pages in hypercall;
- add other 2 commits reducing chunks passed to write/writev.

Changes since v2:
- update patches commit prefixes;
- add other 2 optisations.

Changes since v3:
- address some comments;
- add patches for foreign copy optimisation.

Changes since v4:
- added Reviewed-by;
- improved commit messages;
- other minor fixes, see individual commits.

Changes since v5:
- avoids potential buffer underflow if nr_pages is 0 calling cache_alloc;
- do not overwrite errno if xenforeignmemory_map fails;
- lot of changes to "implement new foreign copy hypercall", see specific
  commit.

Changes since v6:
- removed merged patch;
- keep only optimization commits for now;
- improve comments;
- merged "fill directly iov structure collapsing them" and moved it;
- split "allocate various migration arrays just once";
- add a commit for memory checks using Valgrind.

Changes since v7:
- removed merged commits;
- minor style fixes.

Changes since v8:
- added Reviewed-by;
- remove useless check;
- remove useless memset;
- initialize variables while declaring them.

Edwin Török (2):
  libs/call: cache up to 4 pages in hypercall bounce buffers
  libs/guest: allocate various migration arrays just once

Frediano Ziglio (2):
  libs/guest: move batch_pfns into a separate structure
  libs/guest: use Valgrind to detect various buffer overflows

 tools/libs/call/buffer.c        | 34 ++++++++-----
 tools/libs/call/core.c          |  3 +-
 tools/libs/call/private.h       |  8 ++--
 tools/libs/ctrl/xc_private.h    |  8 ++++
 tools/libs/guest/xg_sr_common.h | 19 +++++++-
 tools/libs/guest/xg_sr_save.c   | 84 ++++++++++++++++-----------------
 6 files changed, 98 insertions(+), 58 deletions(-)

-- 
2.43.0