[Qemu-devel] [RFC 1/5] exec: Add new exclusive bitmap to ram_list

[Alvise Rigo]

The purpose of this new bitmap is to flag the memory pages that are in
the middle of LL/SC operations (after a LL, before a SC).
For all these pages, the corresponding TLB entries will be generated
in such a way to force the slow-path.

The accessors to this bitmap are currently not atomic, but they have to
be so in a real multi-threading TCG.

Suggested-by: Jani Kokkonen <address@hidden>
Suggested-by: Claudio Fontana <address@hidden>
Signed-off-by: Alvise Rigo <address@hidden>
---
 include/exec/cpu-defs.h |  2 ++
 include/exec/memory.h   |  3 ++-
 include/exec/ram_addr.h | 19 ++++++++++++++++++-
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/include/exec/cpu-defs.h b/include/exec/cpu-defs.h
index 0ca6f0b..d12cb4c 100644
--- a/include/exec/cpu-defs.h
+++ b/include/exec/cpu-defs.h
@@ -123,5 +123,7 @@ QEMU_BUILD_BUG_ON(sizeof(CPUTLBEntry) != (1 << 
CPU_TLB_ENTRY_BITS));
 #define CPU_COMMON                                                      \
     /* soft mmu support */                                              \
     CPU_COMMON_TLB                                                      \
+    /* true if in the middle of a LoadLink/StoreConditional */          \
+    bool ll_sc_context;                                                 \
 
 #endif
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 06ffa1d..aadd2cc 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -19,7 +19,8 @@
 #define DIRTY_MEMORY_VGA       0
 #define DIRTY_MEMORY_CODE      1
 #define DIRTY_MEMORY_MIGRATION 2
-#define DIRTY_MEMORY_NUM       3        /* num of dirty bits */
+#define DIRTY_MEMORY_EXCLUSIVE 3
+#define DIRTY_MEMORY_NUM       4        /* num of dirty bits */
 
 #include <stdint.h>
 #include <stdbool.h>
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index ff558a4..7a448ea 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -21,6 +21,7 @@
 
 #ifndef CONFIG_USER_ONLY
 #include "hw/xen/xen.h"
+#include "qemu/bitmap.h"
 
 ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
                                     bool share, const char *mem_path,
@@ -199,9 +200,25 @@ static inline void 
cpu_physical_memory_clear_dirty_range(ram_addr_t start,
     cpu_physical_memory_clear_dirty_range_type(start, length, 
DIRTY_MEMORY_CODE);
 }
 
-
 void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t length,
                                      unsigned client);
 
+static inline void cpu_physical_memory_set_excl_dirty(ram_addr_t addr)
+{
+    clear_bit(addr >> TARGET_PAGE_BITS,
+              ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE]);
+}
+
+static inline int cpu_physical_memory_excl_is_dirty(ram_addr_t addr)
+{
+    return !test_bit(addr >> TARGET_PAGE_BITS,
+                     ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE]);
+}
+
+static inline void cpu_physical_memory_clear_excl_dirty(ram_addr_t addr)
+{
+    set_bit(addr >> TARGET_PAGE_BITS,
+            ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE]);
+}
 #endif
 #endif
-- 
2.4.0