[Qemu-devel] [PATCH 5/5] vga-cirrus: Workaround during restore when using Xen.

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

During the initialisation of the machine at restore time, the access to the
VRAM will fail because QEMU does not know yet the right guest address to map,
so the vram_ptr is NULL.

So this patch avoid using a NULL pointer during initialisation, and try to get
another vram_ptr if the call failed the first time.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/cirrus_vga.c |   20 +++++++++++++++++---
 1 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/hw/cirrus_vga.c b/hw/cirrus_vga.c
index c7e365b..d092c74 100644
--- a/hw/cirrus_vga.c
+++ b/hw/cirrus_vga.c
@@ -32,6 +32,7 @@
 #include "console.h"
 #include "vga_int.h"
 #include "loader.h"
+#include "sysemu.h"
 
 /*
  * TODO:
@@ -2696,6 +2697,17 @@ static int cirrus_post_load(void *opaque, int version_id)
     s->vga.gr[0x01] = s->cirrus_shadow_gr1 & 0x0f;
 
     cirrus_update_memory_access(s);
+    if (!s->vga.vram_ptr) {
+        /* Try again
+         * The initial call to get_ram_ptr can fail with Xen during a migration
+         * because the VRAM has been moved arround.
+         * (Moved with a set_memory and a xen_add_to_physmap)
+         * After cirrus_update_memory_access, the Xen function will know were
+         * the memory actually is, and fix the address before give back a
+         * ram_ptr.
+         */
+        s->vga.vram_ptr = memory_region_get_ram_ptr(&s->vga.vram);
+    }
     /* force refresh */
     s->vga.graphic_mode = -1;
     cirrus_update_bank_ptr(s, 0);
@@ -2784,9 +2796,11 @@ static void cirrus_reset(void *opaque)
     }
     s->vga.cr[0x27] = s->device_id;
 
-    /* Win2K seems to assume that the pattern buffer is at 0xff
-       initially ! */
-    memset(s->vga.vram_ptr, 0xff, s->real_vram_size);
+    if (!runstate_check(RUN_STATE_PREMIGRATE)) {
+        /* Win2K seems to assume that the pattern buffer is at 0xff
+           initially ! */
+        memset(s->vga.vram_ptr, 0xff, s->real_vram_size);
+    }
 
     s->cirrus_hidden_dac_lockindex = 5;
     s->cirrus_hidden_dac_data = 0;
-- 
Anthony PERARD