[Qemu-devel] [PATCH 2/4] xen: Introduce xen_modified_memory.

[Anthony PERARD <anthony.perard@citrix.com>]

This function is to be used during live migration. Every write access to the
guest memory should call this funcion so the Xen tools knows which pages are
dirty.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/xen.h   |    1 +
 xen-all.c  |   21 +++++++++++++++++++++
 xen-stub.c |    4 ++++
 3 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/hw/xen.h b/hw/xen.h
index e5926b7..d14e92d 100644
--- a/hw/xen.h
+++ b/hw/xen.h
@@ -48,6 +48,7 @@ void xenstore_store_pv_console_info(int i, struct CharDriverState *chr);
 struct MemoryRegion;
 void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
                    struct MemoryRegion *mr);
+void xen_modified_memory(ram_addr_t start, ram_addr_t length);
 #endif
 
 struct MemoryRegion;
diff --git a/xen-all.c b/xen-all.c
index 8995d43..498883b 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -1218,3 +1218,24 @@ void xen_shutdown_fatal_error(const char *fmt, ...)
     /* destroy the domain */
     qemu_system_shutdown_request();
 }
+
+void xen_modified_memory(ram_addr_t start, ram_addr_t length)
+{
+    if (unlikely(xen_in_migration)) {
+        int rc;
+        ram_addr_t start_pfn, nb_pages;
+
+        if (length == 0) {
+            length = TARGET_PAGE_SIZE;
+        }
+        start_pfn = start >> TARGET_PAGE_BITS;
+        nb_pages = ((start + length + TARGET_PAGE_SIZE - 1) >> TARGET_PAGE_BITS)
+            - start_pfn;
+        rc = xc_hvm_modified_memory(xen_xc, xen_domid, start_pfn, nb_pages);
+        if (rc) {
+            fprintf(stderr, "%s failed for "RAM_ADDR_FMT" ("RAM_ADDR_FMT
+                    "): %i, %s\n", __func__,
+                    start, nb_pages, rc, strerror(-rc));
+        }
+    }
+}
diff --git a/xen-stub.c b/xen-stub.c
index 5e66ba8..9214392 100644
--- a/xen-stub.c
+++ b/xen-stub.c
@@ -59,3 +59,7 @@ void xen_register_framebuffer(MemoryRegion *mr)
 void qmp_xen_set_global_dirty_log(bool enable, Error **errp)
 {
 }
+
+void xen_modified_memory(ram_addr_t start, ram_addr_t length)
+{
+}
-- 
Anthony PERARD