drm/nv50: implement global channel address space on new VM code

As of this commit, it's guaranteed that if an object is in VRAM that its
GPU virtual address will be constant.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_fbcon.c

@@ -338,8 +338,8 @@ nouveau_fbcon_create(struct nouveau_fbdev *nfbdev,
 			      FBINFO_HWACCEL_IMAGEBLIT;
 	info->flags |= FBINFO_CAN_FORCE_OUTPUT;
 	info->fbops = &nouveau_fbcon_sw_ops;
-	info->fix.smem_start = dev->mode_config.fb_base + nvbo->bo.offset -
-			       dev_priv->vm_vram_base;
+	info->fix.smem_start = dev->mode_config.fb_base +
+			       (nvbo->bo.mem.start << PAGE_SHIFT);
 	info->fix.smem_len = size;
 
 	info->screen_base = nvbo_kmap_obj_iovirtual(nouveau_fb->nvbo);