conf: add support for booting from redirected USB devices

Commit a4c19459 only added the
QEMU capability flag, command line option and added the boot element
for redirdev's in the XML schema.

This patch adds support for parsing and writing the XML with redirdevs
with the boot flag. It also ignores unknown XML elements in redirdev
instead of failing with:
"error: An error occurred, but the cause is unknown"

Bug: https://bugzilla.redhat.com/show_bug.cgi?id=805414
(cherry picked from commit cc244e24)

src/conf/domain_conf.c

@@ -7240,11 +7240,13 @@ error:
 
 static virDomainRedirdevDefPtr
 virDomainRedirdevDefParseXML(const xmlNodePtr node,
+                             virBitmapPtr bootMap,
                              unsigned int flags)
 {
     xmlNodePtr cur;
     virDomainRedirdevDefPtr def;
     char *bus, *type = NULL;
+    int remaining;
 
     if (VIR_ALLOC(def) < 0) {
         virReportOOMError();
@@ -7276,25 +7278,20 @@ virDomainRedirdevDefParseXML(const xmlNodePtr node,
     }
 
     cur = node->children;
-    while (cur != NULL) {
-        if (cur->type == XML_ELEMENT_NODE) {
-            if (xmlStrEqual(cur->name, BAD_CAST "source")) {
-                int remaining;
-
-                remaining = virDomainChrSourceDefParseXML(&def->source.chr, cur, flags,
-                                                          NULL, NULL, NULL, 0);
-                if (remaining != 0)
-                    goto error;
-            }
-        }
-        cur = cur->next;
-    }
+    /* boot gets parsed in virDomainDeviceInfoParseXML
+     * source gets parsed in virDomainChrSourceDefParseXML
+     * we don't know any of the elements that might remain */
+    remaining = virDomainChrSourceDefParseXML(&def->source.chr, cur, flags,
+                                              NULL, NULL, NULL, 0);
+    if (remaining < 0)
+        goto error;
 
     if (def->source.chr.type == VIR_DOMAIN_CHR_TYPE_SPICEVMC) {
         def->source.chr.data.spicevmc = VIR_DOMAIN_CHR_SPICEVMC_USBREDIR;
     }
 
-    if (virDomainDeviceInfoParseXML(node, NULL, &def->info, flags) < 0)
+    if (virDomainDeviceInfoParseXML(node, bootMap, &def->info,
+                                    flags | VIR_DOMAIN_XML_INTERNAL_ALLOW_BOOT) < 0)
         goto error;
 
     if (def->bus == VIR_DOMAIN_REDIRDEV_BUS_USB &&
@@ -7638,7 +7635,7 @@ virDomainDeviceDefPtr virDomainDeviceDefParse(virCapsPtr caps,
             goto error;
     } else if (xmlStrEqual(node->name, BAD_CAST "redirdev")) {
         dev->type = VIR_DOMAIN_DEVICE_REDIRDEV;
-        if (!(dev->data.redirdev = virDomainRedirdevDefParseXML(node, flags)))
+        if (!(dev->data.redirdev = virDomainRedirdevDefParseXML(node, NULL, flags)))
             goto error;
     } else {
         virReportError(VIR_ERR_XML_ERROR,
@@ -8186,7 +8183,8 @@ virDomainDefParseBootXML(xmlXPathContextPtr ctxt,
 
     if (virXPathULong("count(./devices/disk[boot]"
                       "|./devices/interface[boot]"
-                      "|./devices/hostdev[boot])", ctxt, &deviceBoot) < 0) {
+                      "|./devices/hostdev[boot]"
+                      "|./devices/redirdev[boot])", ctxt, &deviceBoot) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("cannot count boot devices"));
         goto cleanup;
@@ -9769,6 +9767,7 @@ static virDomainDefPtr virDomainDefParseXML(virCapsPtr caps,
         goto no_memory;
     for (i = 0 ; i < n ; i++) {
         virDomainRedirdevDefPtr redirdev = virDomainRedirdevDefParseXML(nodes[i],
+                                                                        bootMap,
                                                                         flags);
         if (!redirdev)
             goto error;
@@ -13192,7 +13191,8 @@ virDomainRedirdevDefFormat(virBufferPtr buf,
     virBufferAsprintf(buf, "    <redirdev bus='%s'", bus);
     if (virDomainChrSourceDefFormat(buf, &def->source.chr, false, flags) < 0)
         return -1;
-    if (virDomainDeviceInfoFormat(buf, &def->info, flags) < 0)
+    if (virDomainDeviceInfoFormat(buf, &def->info,
+                                  flags | VIR_DOMAIN_XML_INTERNAL_ALLOW_BOOT) < 0)
         return -1;
     virBufferAddLit(buf, "    </redirdev>\n");