libxl: Correctly initialize vcpu bitmap

The avail_vcpu bitmap has to be allocated before it can be used (using
the maximum allowed value for that). Then for each available VCPU the
bit in the mask has to be set (libxl_bitmap_set takes a bit position
as an argument, not the number of bits to set).

Without this, I would always only get one VCPU for guests created
through libvirt/libxl.
Signed-off-by: NStefan Bader <stefan.bader@canonical.com>

src/libxl/libxl_conf.c

@@ -331,8 +331,10 @@ error:
 }
 
 static int
-libxlMakeDomBuildInfo(virDomainDefPtr def, libxl_domain_config *d_config)
+libxlMakeDomBuildInfo(virDomainObjPtr vm, libxl_domain_config *d_config)
 {
+    virDomainDefPtr def = vm->def;
+    libxlDomainObjPrivatePtr priv = vm->privateData;
     libxl_domain_build_info *b_info = &d_config->b_info;
     int hvm = STREQ(def->os.type, "hvm");
     size_t i;
@@ -343,8 +345,14 @@ libxlMakeDomBuildInfo(virDomainDefPtr def, libxl_domain_config *d_config)
         libxl_domain_build_info_init_type(b_info, LIBXL_DOMAIN_TYPE_HVM);
     else
         libxl_domain_build_info_init_type(b_info, LIBXL_DOMAIN_TYPE_PV);
+
     b_info->max_vcpus = def->maxvcpus;
-    libxl_bitmap_set((&b_info->avail_vcpus), def->vcpus);
+    if (libxl_cpu_bitmap_alloc(priv->ctx, &b_info->avail_vcpus, def->maxvcpus))
+        goto error;
+    libxl_bitmap_set_none(&b_info->avail_vcpus);
+    for (i = 0; i < def->vcpus; i++)
+        libxl_bitmap_set((&b_info->avail_vcpus), i);
+
     if (def->clock.ntimers > 0 &&
         def->clock.timers[0]->name == VIR_DOMAIN_TIMER_NAME_TSC) {
         switch (def->clock.timers[0]->mode) {
@@ -795,14 +803,16 @@ libxlMakeCapabilities(libxl_ctx *ctx)
 
 int
 libxlBuildDomainConfig(libxlDriverPrivatePtr driver,
-                       virDomainDefPtr def, libxl_domain_config *d_config)
+                       virDomainObjPtr vm, libxl_domain_config *d_config)
 {
+    virDomainDefPtr def = vm->def;
+
     libxl_domain_config_init(d_config);
 
     if (libxlMakeDomCreateInfo(driver, def, &d_config->c_info) < 0)
         return -1;
 
-    if (libxlMakeDomBuildInfo(def, d_config) < 0) {
+    if (libxlMakeDomBuildInfo(vm, d_config) < 0) {
         return -1;
     }
 

src/libxl/libxl_conf.h

@@ -126,6 +126,6 @@ libxlMakeVfb(libxlDriverPrivatePtr driver,
 
 int
 libxlBuildDomainConfig(libxlDriverPrivatePtr driver,
-                       virDomainDefPtr def, libxl_domain_config *d_config);
+                       virDomainObjPtr vm, libxl_domain_config *d_config);
 
 #endif /* LIBXL_CONF_H */

src/libxl/libxl_driver.c

@@ -968,7 +968,7 @@ libxlVmStart(libxlDriverPrivatePtr driver, virDomainObjPtr vm,
 
     libxl_domain_config_init(&d_config);
 
-    if (libxlBuildDomainConfig(driver, vm->def, &d_config) < 0)
+    if (libxlBuildDomainConfig(driver, vm, &d_config) < 0)
         goto error;
 
     if (driver->autoballoon && libxlFreeMem(priv, &d_config) < 0) {