commit f9494614898f46e59bc2243de6fb11ebbfc9cda6
author Alexey Perevalov <a.perevalov@samsung.com> Thu Oct 05 14:13:20 2017 +0300
committer Juan Quintela <quintela@redhat.com> Mon Oct 23 18:03:41 2017 +0200
tree 4bca843ea17e88237db53722a1f7792bd527257d
parent 727b9d7e4926755e14d9ac2b09777c51cccb9b80

migration: add bitmap for received page

This patch adds ability to track down already received
pages, it's necessary for calculation vCPU block time in
postcopy migration feature, and for recovery after
postcopy migration failure.

Also it's necessary to solve shared memory issue in
postcopy livemigration. Information about received pages
will be transferred to the software virtual bridge
(e.g. OVS-VSWITCHD), to avoid fallocate (unmap) for
already received pages. fallocate syscall is required for
remmaped shared memory, due to remmaping itself blocks
ioctl(UFFDIO_COPY, ioctl in this case will end with EEXIT
error (struct page is exists after remmap).

Bitmap is placed into RAMBlock as another postcopy/precopy
related bitmaps.

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

migration/ram.c

diff --git a/migration/ram.c b/migration/ram.c
index bd4fc5c..7f6327f 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -45,6 +45,7 @@
 #include "qapi/qmp/qerror.h"
 #include "trace.h"
 #include "exec/ram_addr.h"
+#include "exec/target_page.h"
 #include "qemu/rcu_queue.h"
 #include "migration/colo.h"
 #include "migration/block.h"
@@ -158,6 +159,35 @@
     return ret;
 }
 
+static void ramblock_recv_map_init(void)
+{
+    RAMBlock *rb;
+
+    RAMBLOCK_FOREACH(rb) {
+        assert(!rb->receivedmap);
+        rb->receivedmap = bitmap_new(rb->max_length >> qemu_target_page_bits());
+    }
+}
+
+int ramblock_recv_bitmap_test(RAMBlock *rb, void *host_addr)
+{
+    return test_bit(ramblock_recv_bitmap_offset(host_addr, rb),
+                    rb->receivedmap);
+}
+
+void ramblock_recv_bitmap_set(RAMBlock *rb, void *host_addr)
+{
+    set_bit_atomic(ramblock_recv_bitmap_offset(host_addr, rb), rb->receivedmap);
+}
+
+void ramblock_recv_bitmap_set_range(RAMBlock *rb, void *host_addr,
+                                    size_t nr)
+{
+    bitmap_set_atomic(rb->receivedmap,
+                      ramblock_recv_bitmap_offset(host_addr, rb),
+                      nr);
+}
+
 /*
  * An outstanding page request, on the source, having been received
  * and queued
@@ -2021,6 +2051,8 @@
         goto err;
     }
 
+    bitmap_clear(rb->receivedmap, start >> qemu_target_page_bits(),
+                 length >> qemu_target_page_bits());
     ret = ram_block_discard_range(rb, start, length);
 
 err:
@@ -2607,13 +2639,20 @@
 {
     xbzrle_load_setup();
     compress_threads_load_setup();
+    ramblock_recv_map_init();
     return 0;
 }
 
 static int ram_load_cleanup(void *opaque)
 {
+    RAMBlock *rb;
     xbzrle_load_cleanup();
     compress_threads_load_cleanup();
+
+    RAMBLOCK_FOREACH(rb) {
+        g_free(rb->receivedmap);
+        rb->receivedmap = NULL;
+    }
     return 0;
 }
 
@@ -2828,6 +2867,7 @@
                 ret = -EINVAL;
                 break;
             }
+            ramblock_recv_bitmap_set(block, host);
             trace_ram_load_loop(block->idstr, (uint64_t)addr, flags, host);
         }