libxl: don't ignore the return value from xc_cpuid_apply_policy

Also change libxl__cpuid_legacy to propagate the error from
xc_cpuid_apply_policy into callers.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>

tools/libs/light/libxl_cpuid.c

@@ -426,11 +426,13 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list *cpuid,
     return 0;
 }
 
-void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
-                         libxl_domain_build_info *info)
+int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
+                        libxl_domain_build_info *info)
 {
+    GC_INIT(ctx);
     bool pae = true;
     bool itsc;
+    int r;
 
     /*
      * Gross hack.  Using libxl_defbool_val() here causes libvirt to crash in
@@ -469,8 +471,13 @@ void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
     itsc = (libxl_defbool_val(info->disable_migrate) ||
             info->tsc_mode == LIBXL_TSC_MODE_ALWAYS_EMULATE);
 
-    xc_cpuid_apply_policy(ctx->xch, domid, restore, NULL, 0,
-                          pae, itsc, nested_virt, info->cpuid);
+    r = xc_cpuid_apply_policy(ctx->xch, domid, restore, NULL, 0,
+                              pae, itsc, nested_virt, info->cpuid);
+    if (r)
+        LOGEVD(ERROR, -r, domid, "Failed to apply CPUID policy");
+
+    GC_FREE;
+    return r ? ERROR_FAIL : 0;
 }
 
 static const char *input_names[2] = { "leaf", "subleaf" };

tools/libs/light/libxl_create.c

@@ -1434,6 +1434,7 @@ int libxl__srm_callout_callback_static_data_done(unsigned int missing,
 
     libxl_domain_config *d_config = dcs->guest_config;
     libxl_domain_build_info *info = &d_config->b_info;
+    int rc = 0;
 
     /*
      * CPUID/MSR information is not present in pre Xen-4.14 streams.
@@ -1443,9 +1444,9 @@ int libxl__srm_callout_callback_static_data_done(unsigned int missing,
      * stream doesn't contain any CPUID data.
      */
     if (missing & XGR_SDD_MISSING_CPUID)
-        libxl__cpuid_legacy(ctx, dcs->guest_domid, true, info);
+        rc = libxl__cpuid_legacy(ctx, dcs->guest_domid, true, info);
 
-    return 0;
+    return rc;
 }
 
 void libxl__srm_callout_callback_restore_results(xen_pfn_t store_mfn,

tools/libs/light/libxl_dom.c

@@ -384,7 +384,7 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
      * being migrated-in/restored have CPUID handled during the
      * static_data_done() callback. */
     if (!state->restore)
-        libxl__cpuid_legacy(ctx, domid, false, info);
+        rc = libxl__cpuid_legacy(ctx, domid, false, info);
 
     return rc;
 }

tools/libs/light/libxl_internal.h

@@ -2052,8 +2052,8 @@ typedef yajl_gen_status (*libxl__gen_json_callback)(yajl_gen hand, void *);
 _hidden char *libxl__object_to_json(libxl_ctx *ctx, const char *type,
                                     libxl__gen_json_callback gen, void *p);
 
-_hidden void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool retore,
-                                 libxl_domain_build_info *info);
+_hidden int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool retore,
+                                libxl_domain_build_info *info);
 
 /* Calls poll() again - useful to check whether a signaled condition
  * is still true.  Cannot fail.  Returns currently-true revents. */

tools/libs/light/libxl_nocpuid.c

@@ -34,9 +34,10 @@ int libxl_cpuid_parse_config_xend(libxl_cpuid_policy_list *cpuid,
     return 0;
 }
 
-void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
-                         libxl_domain_build_info *info)
+int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool restore,
+                        libxl_domain_build_info *info)
 {
+    return 0;
 }
 
 yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,