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

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
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4
cputlb.c
View File

@ -125,8 +125,8 @@ void tlb_flush_page(CPUState *cpu, target_ulong addr)
can be detected */
void tlb_protect_code(ram_addr_t ram_addr)
{
cpu_physical_memory_reset_dirty(ram_addr, TARGET_PAGE_SIZE,
DIRTY_MEMORY_CODE);
cpu_physical_memory_test_and_clear_dirty(ram_addr, TARGET_PAGE_SIZE,
DIRTY_MEMORY_CODE);
}
/* update the TLB so that writes in physical page 'phys_addr' are no longer

23
exec.c
View File

@ -852,16 +852,27 @@ static void tlb_reset_dirty_range_all(ram_addr_t start, ram_addr_t length)
}
/* Note: start and end must be within the same ram block. */
void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t length,
unsigned client)
bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
ram_addr_t length,
unsigned client)
{
if (length == 0)
return;
cpu_physical_memory_clear_dirty_range_type(start, length, client);
unsigned long end, page;
bool dirty;
if (tcg_enabled()) {
if (length == 0) {
return false;
}
end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS;
page = start >> TARGET_PAGE_BITS;
dirty = bitmap_test_and_clear_atomic(ram_list.dirty_memory[client],
page, end - page);
if (dirty && tcg_enabled()) {
tlb_reset_dirty_range_all(start, length);
}
return dirty;
}
/* Called from RCU critical section */

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);
}
}
}

11
memory.c
View File

@ -1468,13 +1468,9 @@ void memory_region_set_dirty(MemoryRegion *mr, hwaddr addr,
bool memory_region_test_and_clear_dirty(MemoryRegion *mr, hwaddr addr,
hwaddr size, unsigned client)
{
bool ret;
assert(mr->terminates);
ret = cpu_physical_memory_get_dirty(mr->ram_addr + addr, size, client);
if (ret) {
cpu_physical_memory_reset_dirty(mr->ram_addr + addr, size, client);
}
return ret;
return cpu_physical_memory_test_and_clear_dirty(mr->ram_addr + addr,
size, client);
}
@ -1518,7 +1514,8 @@ void memory_region_reset_dirty(MemoryRegion *mr, hwaddr addr,
hwaddr size, unsigned client)
{
assert(mr->terminates);
cpu_physical_memory_reset_dirty(mr->ram_addr + addr, size, client);
cpu_physical_memory_test_and_clear_dirty(mr->ram_addr + addr, size,
client);
}
int memory_region_get_fd(MemoryRegion *mr)