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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
cputlb.c
View File

@ -125,8 +125,8 @@ void tlb_flush_page(CPUState *cpu, target_ulong addr)
can be detected */ can be detected */
void tlb_protect_code(ram_addr_t ram_addr) void tlb_protect_code(ram_addr_t ram_addr)
{ {
cpu_physical_memory_reset_dirty(ram_addr, TARGET_PAGE_SIZE, cpu_physical_memory_test_and_clear_dirty(ram_addr, TARGET_PAGE_SIZE,
DIRTY_MEMORY_CODE); DIRTY_MEMORY_CODE);
} }
/* update the TLB so that writes in physical page 'phys_addr' are no longer /* 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. */ /* 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, bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
unsigned client) ram_addr_t length,
unsigned client)
{ {
if (length == 0) unsigned long end, page;
return; bool dirty;
cpu_physical_memory_clear_dirty_range_type(start, length, client);
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); tlb_reset_dirty_range_all(start, length);
} }
return dirty;
} }
/* Called from RCU critical section */ /* 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 */ #endif /* not _WIN32 */
static inline void cpu_physical_memory_clear_dirty_range_type(ram_addr_t start, bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
ram_addr_t length, ram_addr_t length,
unsigned client) 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);
}
static inline void cpu_physical_memory_clear_dirty_range(ram_addr_t start, static inline void cpu_physical_memory_clear_dirty_range(ram_addr_t start,
ram_addr_t length) ram_addr_t length)
{ {
cpu_physical_memory_clear_dirty_range_type(start, length, DIRTY_MEMORY_MIGRATION); cpu_physical_memory_test_and_clear_dirty(start, length, DIRTY_MEMORY_MIGRATION);
cpu_physical_memory_clear_dirty_range_type(start, length, DIRTY_MEMORY_VGA); cpu_physical_memory_test_and_clear_dirty(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_CODE);
} }
void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t length,
unsigned client);
static inline static inline
uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest, uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest,
ram_addr_t start, ram_addr_t start,
@ -245,16 +234,14 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest,
} }
} else { } else {
for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) { for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
if (cpu_physical_memory_get_dirty(start + addr, if (cpu_physical_memory_test_and_clear_dirty(
TARGET_PAGE_SIZE, start + addr,
DIRTY_MEMORY_MIGRATION)) { TARGET_PAGE_SIZE,
DIRTY_MEMORY_MIGRATION)) {
long k = (start + addr) >> TARGET_PAGE_BITS; long k = (start + addr) >> TARGET_PAGE_BITS;
if (!test_and_set_bit(k, dest)) { if (!test_and_set_bit(k, dest)) {
num_dirty++; 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, bool memory_region_test_and_clear_dirty(MemoryRegion *mr, hwaddr addr,
hwaddr size, unsigned client) hwaddr size, unsigned client)
{ {
bool ret;
assert(mr->terminates); assert(mr->terminates);
ret = cpu_physical_memory_get_dirty(mr->ram_addr + addr, size, client); return cpu_physical_memory_test_and_clear_dirty(mr->ram_addr + addr,
if (ret) { size, client);
cpu_physical_memory_reset_dirty(mr->ram_addr + addr, size, client);
}
return ret;
} }
@ -1518,7 +1514,8 @@ void memory_region_reset_dirty(MemoryRegion *mr, hwaddr addr,
hwaddr size, unsigned client) hwaddr size, unsigned client)
{ {
assert(mr->terminates); 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) int memory_region_get_fd(MemoryRegion *mr)