net:fcnal-test.sh in ubuntu_kernel_selftests failed on KVM kernel with "Error: Unknown device type."

[Po-Hsu Lin]

With KVM kernel, this test is failing with:
 # With VRF
 #
 # Error: Unknown device type.

 Running 'make run_tests -C net TEST_PROGS=fcnal-test.sh TEST_GEN_PROGS='' TEST_CUSTOM_PROGS='''
 make: Entering directory '/home/ubuntu/autotest/client/tmp/ubuntu_kernel_selftests/src/linux/tools/testing/selftests/net'
 make --no-builtin-rules ARCH=x86 -C ../../../.. headers_install
 make[1]: Entering directory '/home/ubuntu/autotest/client/tmp/ubuntu_kernel_selftests/src/linux'
   INSTALL ./usr/include
 make[1]: Leaving directory '/home/ubuntu/autotest/client/tmp/ubuntu_kernel_selftests/src/linux'
 TAP version 13
 1..1
 # selftests: net: fcnal-test.sh
 #
 # ###########################################################################
 # IPv4 ping
 # ###########################################################################
 #
 #
 # #################################################################
 # No VRF
 #
 # SYSCTL: net.ipv4.raw_l3mdev_accept=0
 #
 # TEST: ping out - ns-B IP [ OK ]
 # TEST: ping out, device bind - ns-B IP [ OK ]
 # TEST: ping out, address bind - ns-B IP [ OK ]
 # TEST: ping out - ns-B loopback IP [ OK ]
 # TEST: ping out, device bind - ns-B loopback IP [ OK ]
 # TEST: ping out, address bind - ns-B loopback IP [ OK ]
 # TEST: ping in - ns-A IP [ OK ]
 # TEST: ping in - ns-A loopback IP [ OK ]
 # TEST: ping local - ns-A IP [ OK ]
 # TEST: ping local - ns-A loopback IP [ OK ]
 # TEST: ping local - loopback [ OK ]
 # TEST: ping local, device bind - ns-A IP [ OK ]
 # TEST: ping local, device bind - ns-A loopback IP [ OK ]
 # TEST: ping local, device bind - loopback [ OK ]
 # TEST: ping out, blocked by rule - ns-B loopback IP [ OK ]
 # TEST: ping in, blocked by rule - ns-A loopback IP [ OK ]
 # TEST: ping out, blocked by route - ns-B loopback IP [ OK ]
 # TEST: ping in, blocked by route - ns-A loopback IP [ OK ]
 # TEST: ping out, unreachable default route - ns-B loopback IP [ OK ]
 # SYSCTL: net.ipv4.raw_l3mdev_accept=1
 #
 # TEST: ping out - ns-B IP [ OK ]
 # TEST: ping out, device bind - ns-B IP [ OK ]
 # TEST: ping out, address bind - ns-B IP [ OK ]
 # TEST: ping out - ns-B loopback IP [ OK ]
 # TEST: ping out, device bind - ns-B loopback IP [ OK ]
 # TEST: ping out, address bind - ns-B loopback IP [ OK ]
 # TEST: ping in - ns-A IP [ OK ]
 # TEST: ping in - ns-A loopback IP [ OK ]
 # TEST: ping local - ns-A IP [ OK ]
 # TEST: ping local - ns-A loopback IP [ OK ]
 # TEST: ping local - loopback [ OK ]
 # TEST: ping local, device bind - ns-A IP [ OK ]
 # TEST: ping local, device bind - ns-A loopback IP [ OK ]
 # TEST: ping local, device bind - loopback [ OK ]
 # TEST: ping out, blocked by rule - ns-B loopback IP [ OK ]
 # TEST: ping in, blocked by rule - ns-A loopback IP [ OK ]
 # TEST: ping out, blocked by route - ns-B loopback IP [ OK ]
 # TEST: ping in, blocked by route - ns-A loopback IP [ OK ]
 # TEST: ping out, unreachable default route - ns-B loopback IP [ OK ]
 # SYSCTL: net.ipv4.ping_group_range=0 2147483647
 #
 # TEST: ping out - ns-B IP [ OK ]
 # TEST: ping out, device bind - ns-B IP [ OK ]
 # TEST: ping out, address bind - ns-B IP [ OK ]
 # TEST: ping out - ns-B loopback IP [ OK ]
 # TEST: ping out, device bind - ns-B loopback IP [ OK ]
 # TEST: ping out, address bind - ns-B loopback IP [ OK ]
 # TEST: ping in - ns-A IP [ OK ]
 # TEST: ping in - ns-A loopback IP [ OK ]
 # TEST: ping local - ns-A IP [ OK ]
 # TEST: ping local - ns-A loopback IP [ OK ]
 # TEST: ping local - loopback [ OK ]
 # TEST: ping local, device bind - ns-A IP [ OK ]
 # TEST: ping local, device bind - ns-A loopback IP [ OK ]
 # TEST: ping local, device bind - loopback [ OK ]
 # TEST: ping out, blocked by rule - ns-B loopback IP [ OK ]
 # TEST: ping in, blocked by rule - ns-A loopback IP [ OK ]
 # TEST: ping out, blocked by route - ns-B loopback IP [ OK ]
 # TEST: ping in, blocked by route - ns-A loopback IP [ OK ]
 # TEST: ping out, unreachable default route - ns-B loopback IP [ OK ]
 #
 # #################################################################
 # With VRF
 #
 # Error: Unknown device type.
 not ok 1 selftests: net: fcnal-test.sh # exit=2

I think this is because the CONFIG_NET_VRF was not enabled:
/boot/config-5.15.0-1029-kvm:# CONFIG_NET_VRF is not set

[Po-Hsu Lin (cypressyew)]

Found on F-kvm 5.4.0-1088.94