virhostcpu.c: introduce virHostCPUGetAvailableCPUsBitmap()

The idea is to have a function that calls virHostCPUGetOnlineBitmap()
but, instead of returning NULL if the host does not have CPU
offlining capabilities,  fall back to a bitmap containing all
present CPUs.

Next patch will use this helper in two other places.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/libvirt_private.syms

@@ -2223,6 +2223,7 @@ virHookPresent;
 
 
 # util/virhostcpu.h
+virHostCPUGetAvailableCPUsBitmap;
 virHostCPUGetCount;
 virHostCPUGetInfo;
 virHostCPUGetKVMMaxVCPUs;

src/util/virhostcpu.c

@@ -1099,6 +1099,36 @@ virHostCPUGetMap(unsigned char **cpumap,
 }
 
 
+/* virHostCPUGetAvailableCPUsBitmap():
+ *
+ * Returns a virBitmap object with all available host CPUs.
+ *
+ * This is a glorified wrapper of virHostCPUGetOnlineBitmap()
+ * that, instead of returning NULL when 'ifndef __linux__' and
+ * the caller having to handle it outside the function, returns
+ * a virBitmap with all the possible CPUs in the host, up to
+ * virHostCPUGetCount(). */
+virBitmapPtr
+virHostCPUGetAvailableCPUsBitmap(void)
+{
+    g_autoptr(virBitmap) bitmap = NULL;
+
+    if (!(bitmap = virHostCPUGetOnlineBitmap())) {
+        int hostcpus;
+
+        if ((hostcpus = virHostCPUGetCount()) < 0)
+            return NULL;
+
+        if (!(bitmap = virBitmapNew(hostcpus)))
+            return NULL;
+
+        virBitmapSetAll(bitmap);
+    }
+
+    return g_steal_pointer(&bitmap);
+}
+
+
 #if HAVE_LINUX_KVM_H && defined(KVM_CAP_PPC_SMT)
 
 /* Get the number of threads per subcore.

src/util/virhostcpu.h

@@ -43,6 +43,8 @@ int virHostCPUGetStats(int cpuNum,
 bool virHostCPUHasBitmap(void);
 virBitmapPtr virHostCPUGetPresentBitmap(void);
 virBitmapPtr virHostCPUGetOnlineBitmap(void);
+virBitmapPtr virHostCPUGetAvailableCPUsBitmap(void);
+
 int virHostCPUGetCount(void);
 int virHostCPUGetThreadsPerSubcore(virArch arch) G_GNUC_NO_INLINE;