[open-vm-tools-devel] Using iopl() in Posix guests

[Anthony L. <an...@co...>]

I'm playing around with guestd in QEMU and I've noticed that iopl/ioperm 
aren't used by anything before doing PIO operations.

I figure this works in VMware b/c you guys are intercepting the backdoor 
io port regardless of CPL/IOPL.  While this is useful for OSes like 
Windows that have no way to change iopl, it would be nice on Posix 
platforms if you did actually use iopl appropriately.

It's a whole lot easier to just take a vmexit for PIO than it is to 
intercept #gp and try to decode whether it was caused by a ring 3 PIO 
instruction.

Regards,

Anthony Liguori