qemu: Refresh capabilities when creating resctrl allocation

Since one of the things in capabilities (info from resctrl updated with data
about caches) can be change on the system by remounting the /sys/fs/resctrl with
different options, the capabilities need to be refreshed.  There is a better fix
in the works, but it's going to be way bigger than this (hence the XXX note
there), so for the time being let's workaround this.  And in order not to slow
down the domain starting, only get the capabilities if there are any cachetunes.

Relates-to: https://bugzilla.redhat.com/show_bug.cgi?id=1540780Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_process.c

@@ -2500,9 +2500,15 @@ qemuProcessResctrlCreate(virQEMUDriverPtr driver,
 {
     int ret = -1;
     size_t i = 0;
-    virCapsPtr caps = virQEMUDriverGetCapabilities(driver, false);
+    virCapsPtr caps = NULL;
     qemuDomainObjPrivatePtr priv = vm->privateData;
 
+    if (!vm->def->ncachetunes)
+        return 0;
+
+    /* Force capability refresh since resctrl info can change
+     * XXX: move cache info into virresctrl so caps are not needed */
+    caps = virQEMUDriverGetCapabilities(driver, true);
     if (!caps)
         return -1;