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
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