qemu: Implement support for 'capability_filters' config option

Filter out the given capabilities and set domain taint if we've done so.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_domain.c

@@ -8339,7 +8339,8 @@ void qemuDomainObjCheckTaint(virQEMUDriverPtr driver,
             custom_hypervisor_feat = true;
     }
 
-    if (custom_hypervisor_feat) {
+    if (custom_hypervisor_feat ||
+        (cfg->capabilityfilters && *cfg->capabilityfilters)) {
         qemuDomainObjTaint(driver, obj,
                            VIR_DOMAIN_TAINT_CUSTOM_HYPERVISOR_FEATURE, logCtxt);
     }

src/qemu/qemu_process.c

@@ -5452,10 +5452,25 @@ static int
 qemuProcessStartUpdateCustomCaps(virDomainObjPtr vm)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
+    VIR_AUTOUNREF(virQEMUDriverConfigPtr) cfg = virQEMUDriverGetConfig(priv->driver);
     qemuDomainXmlNsDefPtr nsdef = vm->def->namespaceData;
+    char **next;
     int tmp;
     size_t i;
 
+    if (cfg->capabilityfilters) {
+        for (next = cfg->capabilityfilters; *next; next++) {
+            if ((tmp = virQEMUCapsTypeFromString(*next)) < 0) {
+                virReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("invalid capability_filters capability '%s'"),
+                               *next);
+                return -1;
+            }
+
+            virQEMUCapsClear(priv->qemuCaps, tmp);
+        }
+    }
+
     if (nsdef) {
         for (i = 0; i < nsdef->ncapsadd; i++) {
             if ((tmp = virQEMUCapsTypeFromString(nsdef->capsadd[i])) < 0) {