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memory: replace cpu_physical_memory_reset_dirty() with test-and-clear

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The cpu_physical_memory_reset_dirty() function is sometimes used
together with cpu_physical_memory_get_dirty().  This is not atomic since
two separate accesses to the dirty memory bitmap are made.

Turn cpu_physical_memory_reset_dirty() and
cpu_physical_memory_clear_dirty_range_type() into the atomic
cpu_physical_memory_test_and_clear_dirty().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <1417519399-3166-6-git-send-email-stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2014-12-02 11:23:18 +00:00 • committed by Paolo Bonzini
parent 20015f72bd
commit 03eebc9e32
4 changed files with 33 additions and 38 deletions
Download patch file Download diff file Expand all files Collapse all files

33
include/exec/ram_addr.h
View file

@ -194,30 +194,19 @@ static inline void cpu_physical_memory_set_dirty_lebitmap(unsigned long *bitmap,
}
#endif /* not _WIN32 */
static inline void cpu_physical_memory_clear_dirty_range_type(ram_addr_t start,
ram_addr_t length,
unsigned client)
{
unsigned long end, page;
assert(client < DIRTY_MEMORY_NUM);
end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS;
page = start >> TARGET_PAGE_BITS;
bitmap_clear(ram_list.dirty_memory[client], page, end - page);
}
bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
ram_addr_t length,
unsigned client);
static inline void cpu_physical_memory_clear_dirty_range(ram_addr_t start,
ram_addr_t length)
{
cpu_physical_memory_clear_dirty_range_type(start, length, DIRTY_MEMORY_MIGRATION);
cpu_physical_memory_clear_dirty_range_type(start, length, DIRTY_MEMORY_VGA);
cpu_physical_memory_clear_dirty_range_type(start, length, DIRTY_MEMORY_CODE);
cpu_physical_memory_test_and_clear_dirty(start, length, DIRTY_MEMORY_MIGRATION);
cpu_physical_memory_test_and_clear_dirty(start, length, DIRTY_MEMORY_VGA);
cpu_physical_memory_test_and_clear_dirty(start, length, DIRTY_MEMORY_CODE);
}
void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t length,
unsigned client);
static inline
uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest,
ram_addr_t start,
@ -245,16 +234,14 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest,
}
} else {
for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
if (cpu_physical_memory_get_dirty(start + addr,
TARGET_PAGE_SIZE,
DIRTY_MEMORY_MIGRATION)) {
if (cpu_physical_memory_test_and_clear_dirty(
start + addr,
TARGET_PAGE_SIZE,
DIRTY_MEMORY_MIGRATION)) {
long k = (start + addr) >> TARGET_PAGE_BITS;
if (!test_and_set_bit(k, dest)) {
num_dirty++;
}
cpu_physical_memory_reset_dirty(start + addr,
TARGET_PAGE_SIZE,
DIRTY_MEMORY_MIGRATION);
}
}
}