diff options
| -rw-r--r-- | include/exec/ram_addr.h | 11 | ||||
| -rw-r--r-- | include/exec/ramblock.h | 3 | ||||
| -rw-r--r-- | include/qemu/bitmap.h | 1 | ||||
| -rw-r--r-- | util/bitmap.c | 45 |
4 files changed, 55 insertions, 5 deletions
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index 1500680458..f4fb6a2111 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -42,7 +42,8 @@ static inline long clear_bmap_size(uint64_t pages, uint8_t shift) } /** - * clear_bmap_set: set clear bitmap for the page range + * clear_bmap_set: set clear bitmap for the page range. Must be with + * bitmap_mutex held. * * @rb: the ramblock to operate on * @start: the start page number @@ -55,12 +56,12 @@ static inline void clear_bmap_set(RAMBlock *rb, uint64_t start, { uint8_t shift = rb->clear_bmap_shift; - bitmap_set_atomic(rb->clear_bmap, start >> shift, - clear_bmap_size(npages, shift)); + bitmap_set(rb->clear_bmap, start >> shift, clear_bmap_size(npages, shift)); } /** - * clear_bmap_test_and_clear: test clear bitmap for the page, clear if set + * clear_bmap_test_and_clear: test clear bitmap for the page, clear if set. + * Must be with bitmap_mutex held. * * @rb: the ramblock to operate on * @page: the page number to check @@ -71,7 +72,7 @@ static inline bool clear_bmap_test_and_clear(RAMBlock *rb, uint64_t page) { uint8_t shift = rb->clear_bmap_shift; - return bitmap_test_and_clear_atomic(rb->clear_bmap, page >> shift, 1); + return bitmap_test_and_clear(rb->clear_bmap, page >> shift, 1); } static inline bool offset_in_ramblock(RAMBlock *b, ram_addr_t offset) diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h index 6cbedf9e0c..adc03df59c 100644 --- a/include/exec/ramblock.h +++ b/include/exec/ramblock.h @@ -53,6 +53,9 @@ struct RAMBlock { * and split clearing of dirty bitmap on the remote node (e.g., * KVM). The bitmap will be set only when doing global sync. * + * It is only used during src side of ram migration, and it is + * protected by the global ram_state.bitmap_mutex. + * * NOTE: this bitmap is different comparing to the other bitmaps * in that one bit can represent multiple guest pages (which is * decided by the `clear_bmap_shift' variable below). On diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h index 82a1d2f41f..3ccb00865f 100644 --- a/include/qemu/bitmap.h +++ b/include/qemu/bitmap.h @@ -253,6 +253,7 @@ void bitmap_set(unsigned long *map, long i, long len); void bitmap_set_atomic(unsigned long *map, long i, long len); void bitmap_clear(unsigned long *map, long start, long nr); bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr); +bool bitmap_test_and_clear(unsigned long *map, long start, long nr); void bitmap_copy_and_clear_atomic(unsigned long *dst, unsigned long *src, long nr); unsigned long bitmap_find_next_zero_area(unsigned long *map, diff --git a/util/bitmap.c b/util/bitmap.c index f81d8057a7..8d12e90a5a 100644 --- a/util/bitmap.c +++ b/util/bitmap.c @@ -240,6 +240,51 @@ void bitmap_clear(unsigned long *map, long start, long nr) } } +bool bitmap_test_and_clear(unsigned long *map, long start, long nr) +{ + unsigned long *p = map + BIT_WORD(start); + const long size = start + nr; + int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG); + unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start); + bool dirty = false; + + assert(start >= 0 && nr >= 0); + + /* First word */ + if (nr - bits_to_clear > 0) { + if ((*p) & mask_to_clear) { + dirty = true; + } + *p &= ~mask_to_clear; + nr -= bits_to_clear; + bits_to_clear = BITS_PER_LONG; + p++; + } + + /* Full words */ + if (bits_to_clear == BITS_PER_LONG) { + while (nr >= BITS_PER_LONG) { + if (*p) { + dirty = true; + *p = 0; + } + nr -= BITS_PER_LONG; + p++; + } + } + + /* Last word */ + if (nr) { + mask_to_clear &= BITMAP_LAST_WORD_MASK(size); + if ((*p) & mask_to_clear) { + dirty = true; + } + *p &= ~mask_to_clear; + } + + return dirty; +} + bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr) { unsigned long *p = map + BIT_WORD(start); |