Bug 1098376

Description of problem:

libvirtd fails to start on Xen instances, particularly the "Fedora 20 (Heisenbug) (PVHVM)" instance type on Rackspace

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[root@devstack-test libvirt-1.1.3.5]# libvirtd 
2014-05-16 03:00:31.376+0000: 23764: info : libvirt version: 1.1.3.5, package: 1.fc20 (Fedora Project, 2014-05-03-21:46:09, buildvm-16.phx2.fedoraproject.org)
2014-05-16 03:00:31.376+0000: 23764: info : virNetlinkEventServiceStart:518 : starting netlink event service with protocol 0
2014-05-16 03:00:31.376+0000: 23764: info : virNetlinkEventServiceStart:518 : starting netlink event service with protocol 15
2014-05-16 03:00:31.386+0000: 23775: info : dnsmasqCapsSetFromBuffer:682 : dnsmasq version is 2.68, --bind-dynamic is present, SO_BINDTODEVICE is in use
2014-05-16 03:00:31.392+0000: 23775: info : networkReloadFirewallRules:1553 : Reloading iptables rules
2014-05-16 03:00:31.805+0000: 23775: info : virIpTablesOnceInit:69 : firewall-cmd found but disabled for iptables
2014-05-16 03:00:32.024+0000: 23775: info : networkRefreshDaemons:1525 : Refreshing network daemons
2014-05-16 03:00:32.024+0000: 23775: info : networkRefreshDhcpDaemon:1171 : Refreshing dnsmasq for network virbr0
2014-05-16 03:00:32.333+0000: 23775: info : ebiptablesDriverInitWithFirewallD:4201 : firewalld support disabled for nwfilter
2014-05-16 03:00:32.375+0000: 23775: error : libxlDriverConfigNew:1089 : cannot initialize libxenlight context, probably not running in a Xen Dom0, disabling driver
2014-05-16 03:00:32.375+0000: 23775: error : virStateInitialize:854 : Initialization of LIBXL state driver failed: Unknown problem
2014-05-16 03:00:32.375+0000: 23775: error : daemonRunStateInit:909 : Driver state initialization failed
2014-05-16 03:00:32.376+0000: 23764: info : virNetlinkEventServiceStopAll:421 : stopping all netlink event services
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I believe the problem there is the "Initialization of LIBXL state driver failed: Unknown problem" which actually makes libvirtd bail out.  libxlDriverShouldLoad() sees /proc/xen/capabilities looking like:

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[root@devstack-test libvirt-1.1.3.5]# ls -l /proc/xen
total 0
-r--r--r--. 1 root root 0 May 16 00:26 capabilities
-rw-------. 1 root root 0 May 16 00:26 privcmd
-rw-------. 1 root root 0 May 16 00:26 xenbus
[root@devstack-test libvirt-1.1.3.5]# cat /proc/xen/capabilities 
[root@devstack-test libvirt-1.1.3.5]# 
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This allows the plugin to load, which calls libxlStateInitialize()->libxlDriverConfigNew(), which returns -1 as it can't find what it's looking for and libvirtd stops.

Looking at upstream git I believe this has been addressed with [1] which checks the /proc/xen/capabilities more carefully.  I believe we should make this available in Fedora and RHEL7; running libvirtd inside instances is critical for upstream OpenStack testing on these platforms.

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[root@devstack-test libvirt-1.1.3.5]# rpm -qa | grep libvirt
libvirt-daemon-qemu-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-interface-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-nwfilter-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-libxl-1.1.3.5-1.fc20.x86_64
libvirt-1.1.3.5-1.fc20.x86_64
libvirt-daemon-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-secret-1.1.3.5-1.fc20.x86_64
libvirt-daemon-config-network-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-uml-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-vbox-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-network-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-qemu-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-xen-1.1.3.5-1.fc20.x86_64
libvirt-debuginfo-1.1.3.5-1.fc20.x86_64
libvirt-client-1.1.3.5-1.fc20.x86_64
libvirt-daemon-config-nwfilter-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-nodedev-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-storage-1.1.3.5-1.fc20.x86_64
libvirt-daemon-driver-lxc-1.1.3.5-1.fc20.x86_64
libvirt-python-1.1.3.5-1.fc20.x86_64
libvirt-daemon-kvm-1.1.3.5-1.fc20.x86_64
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[1] http://libvirt.org/git/?p=libvirt.git;a=commit;h=8c869ad9f9c5d57ba0ef516835a08afdba7ad828