libxl: round memory values to next 1MiB increment

libxl requires the memory sizes to be rounded to 1MiB increments.
Attempting to start a domain that violates this requirement will
fail with the marginally helpful error

2018-02-22 01:55:32.921+0000: xc: panic: xc_dom_boot.c:141: xc_dom_boot_mem_init: can't allocate low memory for domain: Out of memory
2018-02-22 01:55:32.921+0000: libxl: libxl_dom.c:671:libxl__build_dom: xc_dom_boot_mem_init failed: No such file or directory

Round the maximum and current memory values to the next 1MiB
increment when generating the libxl_domain_config object.
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

src/libxl/libxl_conf.c

@@ -367,6 +367,10 @@ libxlMakeDomBuildInfo(virDomainDefPtr def,
     }
 
     b_info->sched_params.weight = 1000;
+    /* Xen requires the memory sizes to be rounded to 1MiB increments */
+    virDomainDefSetMemoryTotal(def,
+                               VIR_ROUND_UP(virDomainDefGetMemoryInitial(def), 1024));
+    def->mem.cur_balloon = VIR_ROUND_UP(def->mem.cur_balloon, 1024);
     b_info->max_memkb = virDomainDefGetMemoryInitial(def);
     b_info->target_memkb = def->mem.cur_balloon;
     if (hvm) {