libxl: describe host topology in capabilities

Add support for describing cpu topology in host cpu element.  In doing
so, refactor hwcaps part to its own helper namely libxlCapsInitCPU to
handle all host cpu related operations, including topology.
Signed-off-by: NJoao Martins <joao.m.martins@oracle.com>

src/libxl/libxl_capabilities.c

@@ -57,12 +57,47 @@ struct guest_arch {
 
 #define XEN_CAP_REGEX "(xen|hvm)-[[:digit:]]+\\.[[:digit:]]+-(aarch64|armv7l|x86_32|x86_64|ia64|powerpc64)(p|be)?"
 
+/* hw_caps is an array of 32-bit words whose meaning is listed in
+ * xen-unstable.hg/xen/include/asm-x86/cpufeature.h.  Each feature
+ * is defined in the form X*32+Y, corresponding to the Y'th bit in
+ * the X'th 32-bit word of hw_cap.
+ */
+static int
+libxlCapsInitCPU(virCapsPtr caps, libxl_physinfo *phy_info)
+{
+    virCPUDefPtr cpu = NULL;
+    int ret = -1;
+    int host_pae;
+
+    if (VIR_ALLOC(cpu) < 0)
+        goto error;
+
+    host_pae = phy_info->hw_cap[0] & LIBXL_X86_FEATURE_PAE_MASK;
+    if (host_pae &&
+        virCapabilitiesAddHostFeature(caps, "pae") < 0)
+        goto error;
+
+    cpu->type = VIR_CPU_TYPE_HOST;
+    cpu->cores = phy_info->cores_per_socket;
+    cpu->threads = phy_info->threads_per_core;
+    cpu->sockets = phy_info->nr_cpus / (cpu->cores * cpu->threads);
+    caps->host.cpu = cpu;
+
+    ret = 0;
+
+ cleanup:
+
+    return ret;
+
+ error:
+    virCPUDefFree(cpu);
+    goto cleanup;
+}
 
 static int
 libxlCapsInitHost(libxl_ctx *ctx, virCapsPtr caps)
 {
     libxl_physinfo phy_info;
-    int host_pae;
 
     if (libxl_get_physinfo(ctx, &phy_info) != 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
@@ -70,14 +105,7 @@ libxlCapsInitHost(libxl_ctx *ctx, virCapsPtr caps)
         return -1;
     }
 
-    /* hw_caps is an array of 32-bit words whose meaning is listed in
-     * xen-unstable.hg/xen/include/asm-x86/cpufeature.h.  Each feature
-     * is defined in the form X*32+Y, corresponding to the Y'th bit in
-     * the X'th 32-bit word of hw_cap.
-     */
-    host_pae = phy_info.hw_cap[0] & LIBXL_X86_FEATURE_PAE_MASK;
-    if (host_pae &&
-        virCapabilitiesAddHostFeature(caps, "pae") < 0)
+    if (libxlCapsInitCPU(caps, &phy_info) < 0)
         return -1;
 
     if (virCapabilitiesSetNetPrefix(caps, LIBXL_GENERATED_PREFIX_XEN) < 0)