libxl: Set default shadow memory based on final values for vcpus and memory

Set default shadow memory based on final versions of memory and vcpus,
not on minimum default versions.

Failure mode was failed p2m allocaitons, e.g., with hvm-linux PV
drivers mapping the shared-info page.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index b5d2eba022..9c37d43e84 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -180,7 +180,7 @@ static void init_build_info(libxl_domain_build_info *b_info, libxl_domain_create
     b_info->max_memkb = 32 * 1024;
     b_info->target_memkb = b_info->max_memkb;
     if (c_info->hvm) {
-        b_info->shadow_memkb = libxl_get_required_shadow_memory(b_info->max_memkb, b_info->max_vcpus);
+        b_info->shadow_memkb = 0; /* Set later */
         b_info->video_memkb = 8 * 1024;
         b_info->kernel = "hvmloader";
         b_info->hvm = 1;
@@ -478,12 +478,17 @@ static void parse_config_data(const char *configfile_filename_report,
         b_info->target_memkb = b_info->max_memkb;
     }
 
+    /* libxl_get_required_shadow_memory() must be called after final values
+     * (default or specified) for vcpus and memory are set, because the
+     * calculation depends on those values. */
+    b_info->shadow_memkb = !xlu_cfg_get_long(config, "shadow_memory", &l)
+        ? l * 1024
+        : libxl_get_required_shadow_memory(b_info->max_memkb,
+                                           b_info->max_vcpus);
+
     if (!xlu_cfg_get_long(config, "tsc_mode", &l))
         b_info->tsc_mode = l;
 
-    if (!xlu_cfg_get_long (config, "shadow_memory", &l))
-        b_info->shadow_memkb = l * 1024;
-
     if (!xlu_cfg_get_long (config, "videoram", &l))
         b_info->video_memkb = l * 1024;