[Qemu-devel] [PATCH] vmstate: Add support for saving/loading bitmaps

[Peter Maydell]

Add support for saving/loading bitmap.h bitmaps in vmstate.

Signed-off-by: Peter Maydell <address@hidden>
---
This will be needed for saving/restoring the bitmap in sd.c which
is introduced by Igor's latest patchset; the relevant VMSTATE line is:
        VMSTATE_BITMAP(wp_groups, SDState, 1, wpgrps_size),
(and you'll need to make wpgrps_size an int32_t, not uint32_t).

Igor: I've only tested this fairly lightly, you'll probably want to
do things like testing save on 32 bit and load on 64 bit and
vice-versa.

 savevm.c  |   41 +++++++++++++++++++++++++++++++++++++++++
 vmstate.h |   13 +++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/savevm.c b/savevm.c
index 6e82b2d..0e2de97 100644
--- a/savevm.c
+++ b/savevm.c
@@ -86,6 +86,7 @@
 #include "memory.h"
 #include "qmp-commands.h"
 #include "trace.h"
+#include "bitops.h"
 
 #define SELF_ANNOUNCE_ROUNDS 5
 
@@ -1159,6 +1160,46 @@ const VMStateInfo vmstate_info_unused_buffer = {
     .put  = put_unused_buffer,
 };
 
+/* bitmaps (as defined by bitmap.h). Note that size here is the size
+ * of the bitmap in bits. The on-the-wire format of a bitmap is 64
+ * bit words with the bits in big endian order. The in-memory format
+ * is an array of 'unsigned long', which may be either 32 or 64 bits.
+ */
+/* This is the number of 64 bit words sent over the wire */
+#define BITS_TO_U64S(nr) DIV_ROUND_UP(nr, 64)
+static int get_bitmap(QEMUFile *f, void *pv, size_t size)
+{
+    unsigned long *bmp = pv;
+    int i, idx = 0;
+    for (i = 0; i < BITS_TO_U64S(size); i++) {
+        uint64_t w = qemu_get_be64(f);
+        bmp[idx++] = w;
+        if (sizeof(unsigned long) == 4 && idx < BITS_TO_LONGS(size)) {
+            bmp[idx++] = w >> 32;
+        }
+    }
+    return 0;
+}
+
+static void put_bitmap(QEMUFile *f, void *pv, size_t size)
+{
+    unsigned long *bmp = pv;
+    int i, idx = 0;
+    for (i = 0; i < BITS_TO_U64S(size); i++) {
+        uint64_t w = bmp[idx++];
+        if (sizeof(unsigned long) == 4 && idx < BITS_TO_LONGS(size)) {
+            w |= ((uint64_t)bmp[idx++]) << 32;
+        }
+        qemu_put_be64(f, w);
+    }
+}
+
+const VMStateInfo vmstate_info_bitmap = {
+    .name = "bitmap",
+    .get = get_bitmap,
+    .put = put_bitmap,
+};
+
 typedef struct CompatEntry {
     char idstr[256];
     int instance_id;
diff --git a/vmstate.h b/vmstate.h
index 5bd2b76..c45f46e 100644
--- a/vmstate.h
+++ b/vmstate.h
@@ -139,6 +139,7 @@ extern const VMStateInfo vmstate_info_uint64;
 extern const VMStateInfo vmstate_info_timer;
 extern const VMStateInfo vmstate_info_buffer;
 extern const VMStateInfo vmstate_info_unused_buffer;
+extern const VMStateInfo vmstate_info_bitmap;
 
 #define type_check_array(t1,t2,n) ((t1(*)[n])0 - (t2*)0)
 #define type_check_pointer(t1,t2) ((t1**)0 - (t2*)0)
@@ -411,6 +412,18 @@ extern const VMStateInfo vmstate_info_unused_buffer;
     .flags        = VMS_BUFFER,                                      \
 }
 
+/* _field_size should be a uint32_t field in the _state struct giving the
+ * size of the bitmap _field in bits.
+ */
+#define VMSTATE_BITMAP(_field, _state, _version, _field_size) {      \
+    .name         = (stringify(_field)),                             \
+    .version_id   = (_version),                                      \
+    .size_offset  = vmstate_offset_value(_state, _field_size, int32_t),\
+    .info         = &vmstate_info_bitmap,                            \
+    .flags        = VMS_VBUFFER|VMS_POINTER,                         \
+    .offset       = offsetof(_state, _field),                        \
+}
+
 /* _f : field name
    _f_n : num of elements field_name
    _n : num of elements
-- 
1.7.9.5