Advisory: XSA-308

The VMX VMEntry checks does not like the exact combination of state which occurs when #DB in intercepted, Single Stepping is active, and blocked by STI/MovSS is active, despite this being a legitimate state to be in.

The exact sequence is the interaction of a MovSS-deferred ICEBP #DB while Single Stepping is active. A related sequence which tickles the same failure is an STI while Single Stepping is active.

Run both of these sequences. If the VM is still alive at the end, it didn't suffer a VMEntry failure.

See also: tests/xsa-308/main.c