[PATCH 2 of 2 v2] xl: check for meaningful combination of sedf config file parameters

[Dario Faggioli <raistlin@linux.it>]

As it happens in the implementation of `xl sched-sedf -d ...', some
consistency checking is needed for the scheduling parameters when
they come from the config file.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -550,6 +550,31 @@ vcpp_out:
     return rc;
 }
 
+static int sched_params_valid(libxl_domain_sched_params *scp)
+{
+    int has_weight = scp->weight != LIBXL_DOMAIN_SCHED_PARAM_WEIGHT_DEFAULT;
+    int has_period = scp->period != LIBXL_DOMAIN_SCHED_PARAM_PERIOD_DEFAULT;
+    int has_slice = scp->slice != LIBXL_DOMAIN_SCHED_PARAM_SLICE_DEFAULT;
+    libxl_domain_sched_params sci;
+
+    libxl_domain_sched_params_get(ctx, domid, &sci);
+
+    /* The sedf scheduler needs some more consistency checking */
+    if (sci.sched == LIBXL_SCHEDULER_SEDF) {
+        if (has_weight && (has_period || has_slice))
+            return 0;
+
+        if (has_weight) {
+            scp->slice = 0;
+            scp->period = 0;
+        }
+        if (has_period || has_slice)
+            scp->weight = 0;
+    }
+
+    return 1;
+}
+
 static void parse_config_data(const char *config_source,
                               const char *config_data,
                               int config_len,
@@ -644,6 +669,10 @@ static void parse_config_data(const char
         b_info->sched_params.latency = l;
     if (!xlu_cfg_get_long (config, "extratime", &l, 0))
         b_info->sched_params.extratime = l;
+    if (!sched_params_valid(&b_info->sched_params)) {
+        fprintf(stderr, "Invalid scheduling parameters\n");
+        exit(1);
+    }
 
     if (!xlu_cfg_get_long (config, "vcpus", &l, 0)) {
         b_info->max_vcpus = l;