From 03eebc9e3246b9b3f5925aa41f7dfd7c1e467875 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 2 Dec 2014 11:23:18 +0000 Subject: [PATCH] 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 Message-Id: <1417519399-3166-6-git-send-email-stefanha@redhat.com> Reviewed-by: Fam Zheng Signed-off-by: Paolo Bonzini --- cputlb.c | 4 ++-- exec.c | 23 +++++++++++++++++------ include/exec/ram_addr.h | 33 ++++++++++----------------------- memory.c | 11 ++++------- 4 files changed, 33 insertions(+), 38 deletions(-) diff --git a/cputlb.c b/cputlb.c index dd1203b938..a50608676c 100644 --- a/cputlb.c +++ b/cputlb.c @@ -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 diff --git a/exec.c b/exec.c index 162c57908e..487583b1bd 100644 --- a/exec.c +++ b/exec.c @@ -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 */ diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index 63db371850..a2beea7925 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -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); } } } diff --git a/memory.c b/memory.c index 418cac7ce1..0c5d32807e 100644 --- a/memory.c +++ b/memory.c @@ -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)