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exec: fix access to ram_list.dirty_memory when sync dirty bitmap 

In cpu_physical_memory_sync_dirty_bitmap(rb, start, ...), the 2nd
argument 'start' is relative to the start of the ramblock 'rb'. When
it's used to access the dirty memory bitmap of ram_list (i.e.
ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]->blocks[]), an offset to
the start of all RAM (i.e. rb->offset) should be added to it, which has
however been missed since c/s 6b6712efcc. For a ramblock of host memory
backend whose offset is not zero, cpu_physical_memory_sync_dirty_bitmap()
synchronizes the incorrect part of the dirty memory bitmap of ram_list
to the per ramblock dirty bitmap. As a result, a guest with host
memory backend may crash after migration.

Fix it by adding the offset of ramblock when accessing the dirty memory
bitmap of ram_list in cpu_physical_memory_sync_dirty_bitmap().

Reported-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Message-Id: <20170628083704.24997-1-haozhong.zhang@intel.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Tested-by: Juan Quintela <quintela@redhat.com>
Tested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Haozhong Zhang 2017-06-28 16:37:04 +08:00 committed by Juan Quintela
parent c788ada816
commit 084140bd49
1 changed files with 6 additions and 3 deletions
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9
include/exec/ram_addr.h
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@ -386,8 +386,9 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
int k;
int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS);
unsigned long * const *src;
unsigned long idx = (page * BITS_PER_LONG) / DIRTY_MEMORY_BLOCK_SIZE;
unsigned long offset = BIT_WORD((page * BITS_PER_LONG) %
unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
unsigned long idx = (word * BITS_PER_LONG) / DIRTY_MEMORY_BLOCK_SIZE;
unsigned long offset = BIT_WORD((word * BITS_PER_LONG) %
DIRTY_MEMORY_BLOCK_SIZE);
rcu_read_lock();
@ -414,9 +415,11 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
rcu_read_unlock();
} else {
ram_addr_t offset = rb->offset;
for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
if (cpu_physical_memory_test_and_clear_dirty(
start + addr,
start + addr + offset,
TARGET_PAGE_SIZE,
DIRTY_MEMORY_MIGRATION)) {
*real_dirty_pages += 1;