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From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Subject: [Qemu-devel] [PATCH 20/22] memory: replace cpu_physical_memory_reset_dirty() with test-and-clear
Date: Thu, 26 Mar 2015 18:38:38 +0100	[thread overview]
Message-ID: <1427391520-29497-21-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1427391520-29497-1-git-send-email-pbonzini@redhat.com>

From: Stefan Hajnoczi <stefanha@redhat.com>

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>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 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 38f2151..d7aecab 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 83c58ff..42ed66e 100644
--- a/exec.c
+++ b/exec.c
@@ -857,16 +857,27 @@ 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 (length == 0) {
+        return false;
+    }
 
-    if (tcg_enabled()) {
+    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 a68bde2..b7357ac 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -190,30 +190,19 @@ 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,
@@ -241,12 +230,10 @@ 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)) {
-                cpu_physical_memory_reset_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++;
diff --git a/memory.c b/memory.c
index 6061b27..3eea46f 100644
--- a/memory.c
+++ b/memory.c
@@ -1387,13 +1387,9 @@ 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);
 }
 
 
@@ -1437,7 +1433,8 @@ 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)
-- 
2.3.3

  parent reply	other threads:[~2015-03-26 17:39 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-26 17:38 [Qemu-devel] [PATCH 00/22] Dirty bitmap atomic access and optimizations Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 01/22] memory: add memory_region_ram_resize Paolo Bonzini
2015-03-28 18:58   ` Michael S. Tsirkin
2015-03-29  7:30     ` Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 02/22] acpi-build: remove dependency from ram_addr.h Paolo Bonzini
2015-03-28 18:58   ` Michael S. Tsirkin
2015-03-26 17:38 ` [Qemu-devel] [PATCH 03/22] memory: the only dirty memory flag for users is DIRTY_MEMORY_VGA Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 04/22] display: enable DIRTY_MEMORY_VGA tracking explicitly Paolo Bonzini
2015-04-20 13:11   ` Stefan Hajnoczi
2015-04-20 13:54     ` Paolo Bonzini
2015-04-22  9:12       ` Stefan Hajnoczi
2015-03-26 17:38 ` [Qemu-devel] [PATCH 05/22] memory: return bitmap from memory_region_is_logging Paolo Bonzini
2015-03-27  5:44   ` Fam Zheng
2015-03-27  6:01     ` Paolo Bonzini
2015-03-28 18:54   ` Michael S. Tsirkin
2015-03-29  7:33     ` Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 06/22] framebuffer: check memory_region_is_logging Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 07/22] ui/console: " Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 08/22] memory: track DIRTY_MEMORY_CODE in mr->dirty_log_mask Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 09/22] memory: return DIRTY_MEMORY_MIGRATION from memory_region_is_logging Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 10/22] ram_addr: tweaks to xen_modified_memory Paolo Bonzini
2015-03-28 19:04   ` Stefano Stabellini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 11/22] exec: simplify notdirty_mem_write Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 12/22] exec: use memory_region_is_logging to optimize dirty tracking Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 13/22] exec: pass client mask to cpu_physical_memory_set_dirty_range Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 14/22] exec: only check relevant bitmaps for cleanliness Paolo Bonzini
2015-03-27  6:10   ` Fam Zheng
2015-03-27  9:19     ` Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 15/22] memory: do not touch code dirty bitmap unless TCG is enabled Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 16/22] bitmap: add atomic set functions Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 17/22] bitmap: add atomic test and clear Paolo Bonzini
2015-03-27  6:37   ` Fam Zheng
2015-03-27  9:21     ` Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 18/22] memory: use atomic ops for setting dirty memory bits Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 19/22] migration: move dirty bitmap sync to ram_addr.h Paolo Bonzini
2015-03-26 17:38 ` Paolo Bonzini [this message]
2015-03-26 17:38 ` [Qemu-devel] [PATCH 21/22] memory: make cpu_physical_memory_sync_dirty_bitmap() fully atomic Paolo Bonzini
2015-03-26 17:38 ` [Qemu-devel] [PATCH 22/22] migration: run bitmap sync outside iothread lock Paolo Bonzini
2015-04-20 13:23 ` [Qemu-devel] [PATCH 00/22] Dirty bitmap atomic access and optimizations Stefan Hajnoczi

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