I usually use `cu`, but the docs for minicom tell me it's control-A followed by F to send a break signal. Then just hit "u." There are a number of single characters following a break with actions to them, the full doc on this kernel feature is here: https://www.kernel.org/doc/Documentation/admin-guide/sysrq.r...

I'm not terribly familiar with KVM but the VM console tools probably have some way to generate a break signal. Check the docs for how to "send a break."

Oh, and don't forget to enable this feature via sysctl -- per the above linux doc.