qxl: fix local renderer

The local spice renderer assumes the primary surface is located at the
start of the "ram" bar.  This used to be a requirement in qxl hardware
revision 1.  In revision 2+ this is relaxed.  Nevertheless guest drivers
continued to use the traditional location, for historical and backward
compatibility reasons.  The qxl kms driver doesn't though as it depends
on qxl revision 4+ anyway.

Result is that local rendering is hosed for recent linux guests, you'll
get pixel garbage with non-spice ui (gtk, sdl, vnc) and when doing
screendumps.  Fix that by doing a proper mapping of the guest-specified
memory location.

https://bugzilla.redhat.com/show_bug.cgi?id=948717Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/display/qxl-render.c

@@ -31,10 +31,6 @@ static void qxl_blit(PCIQXLDevice *qxl, QXLRect *rect)
     if (is_buffer_shared(surface)) {
         return;
     }
-    if (!qxl->guest_primary.data) {
-        trace_qxl_render_blit_guest_primary_initialized();
-        qxl->guest_primary.data = memory_region_get_ram_ptr(&qxl->vga.vram);
-    }
     trace_qxl_render_blit(qxl->guest_primary.qxl_stride,
             rect->left, rect->right, rect->top, rect->bottom);
     src = qxl->guest_primary.data;
@@ -104,7 +100,12 @@ static void qxl_render_update_area_unlocked(PCIQXLDevice *qxl)
 
     if (qxl->guest_primary.resized) {
         qxl->guest_primary.resized = 0;
-        qxl->guest_primary.data = memory_region_get_ram_ptr(&qxl->vga.vram);
+        qxl->guest_primary.data = qxl_phys2virt(qxl,
+                                                qxl->guest_primary.surface.mem,
+                                                MEMSLOT_GROUP_GUEST);
+        if (!qxl->guest_primary.data) {
+            return;
+        }
         qxl_set_rect_to_surface(qxl, &qxl->dirty[0]);
         qxl->num_dirty_rects = 1;
         trace_qxl_render_guest_primary_resized(
@@ -128,6 +129,10 @@ static void qxl_render_update_area_unlocked(PCIQXLDevice *qxl)
         }
         dpy_gfx_replace_surface(vga->con, surface);
     }
+
+    if (!qxl->guest_primary.data) {
+        return;
+    }
     for (i = 0; i < qxl->num_dirty_rects; i++) {
         if (qemu_spice_rect_is_empty(qxl->dirty+i)) {
             break;