Avi Kivity wrote:
On 08/03/2009 05:04 PM, Anthony Liguori wrote:
Actually, VT mandates that vmcalls can only be done from CPL=0.
That's exactly how I misremembered it. However the docs say
IF not in VMX operation
THEN #UD;
ELSIF in VMX non-root operation
THEN VM exit;
ELSIF (RFLAGS.VM = 1) OR (IA32_EFER.LMA = 1 and CS.L = 0)
THEN #UD;
ELSIF CPL > 0
THEN #GP(0);
So CPL > 0 is only enforced on VMCALL from the hypervisor, not the
guest (tip: don't ask what VMCALL in the hypervisor means).
Ah, it's used to call SMM peer mode... awesome :-)
Regards,
Anthony Liguori
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