guest OS on Xen can't connect to Domain-0

Question

I'm working on Xen hypervisor on Xubuntu 22.04. I have the trouble to configure the network between host and guest OS. Technically, ping can't reach each other.

Host: Xubuntu 22.04 Guest: Alpine Linux 3.17.1

Guest was created and installed by 'xl create -f ', in which has "vif = [ 'bridge=xenbr0' ]" parameter.

Here's the logs from Host and Guest side.

Host side:

$ ip a
...
3: xenbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 66:92:37:79:3d:28 brd ff:ff:ff:ff:ff:ff
    inet 192.168.14.100/24 scope global xenbr0
       valid_lft forever preferred_lft forever
    inet6 fe80::6492:37ff:fe79:3d28/64 scope link 
       valid_lft forever preferred_lft forever
5: vif3.0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master xenbr0 state UP group default qlen 32
    link/ether fe:ff:ff:ff:ff:ff brd ff:ff:ff:ff:ff:ff
    inet 192.168.14.1/24 scope global vif3.0
       valid_lft forever preferred_lft forever

$ sudo xl network-list 3
Idx BE Mac Addr.         handle state evt-ch   tx-/rx-ring-ref BE-path                       
0   0  00:16:3e:79:a4:ce     0     4     -1    -1/-1          /local/domain/0/backend/vif/3/0

$ brctl show
bridge name bridge id       STP enabled interfaces
xenbr0      8000.669237793d28   no      vif3.0

Guest side:

localhost:/etc/network# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 00:16:3e:79:a4:ce brd ff:ff:ff:ff:ff:ff
    inet 192.168.14.2/24 brd 192.168.14.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::216:3eff:fe79:a4ce/64 scope link 
       valid_lft forever preferred_lft forever

Please let me know if any other information is needed. Thanks.

Answer 1

The -1 values in the xl output look suspicious. Are the event channel (xen-evtchn) and grant table (xen-gntdev) kernel modules loaded in the dom0? I would expect an error from libxl in case these interfaces are missing, since they are not really optional in the ordinary Xen environment.