On Mon, 2022-11-14 at 18:38 +0100, Cédric Le Goater wrote: > When a virtio console port is initialized, it is registered as an hvc > console using a virtual console number. If a KVM guest is started with > multiple virtio console devices, the same vtermno (or virtual console > number) can be used to allocate different hvc consoles, which leads to > various communication problems later on. > > This is also reported in debugfs : > > # grep vtermno /sys/kernel/debug/virtio-ports/* > /sys/kernel/debug/virtio-ports/vport1p1:console_vtermno: 1 > /sys/kernel/debug/virtio-ports/vport2p1:console_vtermno: 1 > /sys/kernel/debug/virtio-ports/vport3p1:console_vtermno: 2 > /sys/kernel/debug/virtio-ports/vport4p1:console_vtermno: 3 > > Replace the next_vtermno global with an ID allocator and start the > allocation at 1 as it is today. Also recycle IDs when a console port > is removed. When the original virtio_console module was written, it didn't have support for multiple ports to be used this way. So the oddity you're seeing is left there deliberately: VMMs should not be instantiating console ports this way. I don't know if we should take in this change, but can you walk through all combinations of new/old guest and new/old hypervisor and ensure nothing's going to break -- and confirm with the spec this is still OK to do? It may not be a goal to still ensure launches of a new guest on a very old (say) Centos5 guest still works -- but that was the point of maintaining backward compat... Amit _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
