Signed-off-by: Benoit Hudzia <benoit.hud...@sap.com> Signed-off-by: Petter Svard <pett...@cs.umu.se> Signed-off-by: Aidan Shribman <aidan.shrib...@sap.com> Signed-off-by: Orit Wasserman <owass...@redhat.com> --- migration.h | 4 ++ savevm.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 176 insertions(+), 0 deletions(-)
diff --git a/migration.h b/migration.h index 1ae99f1..7582ecb 100644 --- a/migration.h +++ b/migration.h @@ -99,4 +99,8 @@ void migrate_add_blocker(Error *reason); */ void migrate_del_blocker(Error *reason); +int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen, + uint8_t *dst, int dlen); +int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen); + #endif diff --git a/savevm.c b/savevm.c index d1d9020..2ab0986 100644 --- a/savevm.c +++ b/savevm.c @@ -2374,3 +2374,175 @@ void vmstate_register_ram_global(MemoryRegion *mr) { vmstate_register_ram(mr, NULL); } + +/* + page = zrun nzrun + | zrun nzrun page + + zrun = length + + nzrun = length byte... + + length = uleb128 encoded integer + */ +int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen, + uint8_t *dst, int dlen) +{ + uint32_t zrun_len = 0, nzrun_len = 0; + int d = 0, i = 0, start; + long res, xor; + uint8_t *nzrun_start = NULL; + + g_assert(!((uintptr_t)old_buf & (sizeof(long) - 1)) && + !((uintptr_t)new_buf & (sizeof(long) - 1)) && + !(slen & (sizeof(long) - 1))); + + while (i < slen) { + /* overflow */ + if (d + 2 > dlen) { + return -1; + } + + /* not aligned to sizeof(long) */ + res = (slen - i) % sizeof(long); + if (res) { + start = i; + while (!(old_buf[i] ^ new_buf[i]) && (i - start) <= res) { + zrun_len++; + i++; + } + } + + if (zrun_len == res) { + while (i <= (slen - sizeof(long)) && + (*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) { + i += sizeof(long); + zrun_len += sizeof(long); + } + + /* go over the rest */ + while (old_buf[i] == new_buf[i] && ++i <= slen) { + zrun_len++; + } + } + + /* buffer unchanged */ + if (zrun_len == slen) { + return 0; + } + + /* skip last zero run */ + if (i == slen + 1) { + return d; + } + + d += uleb128_encode_small(dst + d, zrun_len); + + /* no nzrun */ + if (i == slen) { + return d; + } + + zrun_len = 0; + nzrun_start = new_buf + i; + + /* not aligned to sizeof(long) */ + res = (slen - i) % sizeof(long); + if (res) { + start = i; + while (old_buf[i] != new_buf[i] && i - start < res) { + i++; + nzrun_len++; + } + } + + if (nzrun_len == res) { + /* truncation to 32-bit long okay */ + long mask = 0x0101010101010101ULL; + xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i); + printf("cont\n"); + while (i <= (slen - sizeof(long))) { + if ((xor - mask) & ~xor & (mask << 7)) { + /* found the end of an nzrun within the current long */ + while (old_buf[i] != new_buf[i] && ++i <= slen) { + nzrun_len++; + } + break; + } else { + i += sizeof(long); + nzrun_len += sizeof(long); + xor = *(long *)(old_buf + i) ^ *(long *)(new_buf + i); + } + } + + while (old_buf[i] != new_buf[i] && ++i <= slen) { + nzrun_len++; + } + } + + /* overflow */ + if (d + nzrun_len + 2 > dlen) { + return -1; + } + + d += uleb128_encode_small(dst + d, nzrun_len); + memcpy(dst + d, nzrun_start, nzrun_len); + d += nzrun_len; + nzrun_len = 0; + } + + return d; +} + +int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen) +{ + int i = 0, d = 0; + int ret; + uint32_t count = 0; + + while (i < slen) { + + /* zrun */ + if ((slen - i) < 2 && *(src + i) & 0x80) { + return -1; + } + + ret = uleb128_decode_small(src + i, &count); + if (ret < 0) { + return -1; + } + i += ret; + d += count; + + /* overflow */ + if (d > dlen) { + return -1; + } + + /* completed decoding */ + if (i == slen - 1) { + return d; + } + + /* nzrun */ + if ((slen - i) < 2 && *(src + i) & 0x80) { + return -1; + } + ret = uleb128_decode_small(src + i, &count); + if (ret < 0) { + return -1; + } + i += ret; + + /* overflow */ + if (d + count > dlen) { + return -1; + } + + memcpy(dst + d , src + i, count); + d += count; + i += count; + } + + return d; +} -- 1.7.7.6