fix(cloud-hypervisor): DO not set mtu option for network device

Do not use the MTU option in network device for cloud-hypervisor because
it will try to set this MTU value in the tap device and this operation
requires CAP_NET_ADMIN. Cloud-hypervisor will still advertise the
correct MTU value to the guest, since it reads it from the TAP device.

PR: #1054
Signed-off-by: Charalampos Mainas <charalampos.mainas@gmail.com>
Reviewed-by: Anastassios Nanos <ananos@nubificus.co.uk>
Approved-by: Anastassios Nanos <ananos@nubificus.co.uk>

Author: cmainas

pkg/unikontainers/hypervisors/cloud_hypervisor.go

@@ -115,7 +115,7 @@ func (ch *CloudHypervisor) BuildExecCmd(args types.ExecArgs, ukernel types.Unike
 		netCli := ukernel.MonitorNetCli(args.Net.TapDev, args.Net.MAC)
 		if len(netCli) == 0 {
 			// Default network configuration for Cloud Hypervisor
-			netArg := fmt.Sprintf("tap=%s,mac=%s,mtu=%d", args.Net.TapDev, args.Net.MAC, args.Net.MTU)
+			netArg := fmt.Sprintf("tap=%s,mac=%s", args.Net.TapDev, args.Net.MAC)
 			exArgs = append(exArgs, "--net", netArg)
 		} else {
 			exArgs = append(exArgs, netCli...)