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| author | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2015-12-10 16:31:46 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2015-12-11 12:51:27 +0000 |
| commit | 3fd3c4b37c116cce7e9810fcc15a0a2cf15115a5 (patch) | |
| tree | 388fdaa41ba161791897718ed5c8a5688f682c07 | |
| parent | b969526adf3d77c4a70d7aae41a2f6dccbd024a7 (diff) | |
| download | qemu-3fd3c4b37c116cce7e9810fcc15a0a2cf15115a5.tar.gz | |
Fix xbzrle vs last_sent_block update
My fix (84e7b80a) replaced the last_sent_block update that I'd
removed earlier; however it was too aggressive in the xbzrle case.
save_xbzrle_page might return '0' to mean that the page didn't
need sending since it was the same as the last sent version;
in this case we can't update 'last_sent_block' since we didn't
actually send it.
Symptom: 'Illegal RAM offset 1018000' as we try and send a page
to the wrong RAMBlock; potentially that could be a data
corruption if you were really unlucky.
Fixes: 84e7b80a05c0c44b90533c6cd2f1db5c932ccf77
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-id: 1449765106-6528-1-git-send-email-dgilbert@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
| -rw-r--r-- | migration/ram.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/migration/ram.c b/migration/ram.c index 1eb155aedd..0490f005dd 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -716,6 +716,9 @@ static int save_zero_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset, * ram_save_page: Send the given page to the stream * * Returns: Number of pages written. + * < 0 - error + * >=0 - Number of pages written - this might legally be 0 + * if xbzrle noticed the page was the same. * * @f: QEMUFile where to send the data * @block: block that contains the page we want to send @@ -1249,7 +1252,13 @@ static int ram_save_target_page(MigrationState *ms, QEMUFile *f, if (unsentmap) { clear_bit(dirty_ram_abs >> TARGET_PAGE_BITS, unsentmap); } - last_sent_block = block; + /* Only update last_sent_block if a block was actually sent; xbzrle + * might have decided the page was identical so didn't bother writing + * to the stream. + */ + if (res > 0) { + last_sent_block = block; + } } return res; |