bhyve: create all vcpus on startup

[corvink]

Summary

vcpus could be restarted by the guest by sending an INIT SIPI SIPI
sequence to a vcpu. That's not supported by bhyve yet but it will be
supported in a future commit. So, create the vcpu threads only once on
startup to make restarting a vcpu easier.

[jhb]

I think the general idea is ok, just some nits

usr.sbin/bhyve/bhyverun.c

551

s/int suspend/bool suspend/

689

Looks like pvcpu isn't used anymore?

1139

bool here as well.

1594

I would maybe write this as:

     bool suspend = (vcpu != BSP);
#ifdef BHYVE_SNAPSHOT;
     if (restore_file != NULL)
         suspend = false;
#endif

[corvink]

usr.sbin/bhyve/bhyverun.c

689

Yes, it's unused. Should we mark it as unused?

[corvink]

• fix some nits

[jhb]

usr.sbin/bhyve/bhyverun.c

689

Oh, never mind, I see it's required as part of being a vmexit handler.

1594

s/int/bool/

[corvink]

• s/int/bool/

[corvink]

• add context to diff file

[manu]

@jhb seems all comments have been resolved, will commit later today unless you have objections.