KVM selftests changes for 7.3, part 1
- Clean up nested SVM's handling of GPRs on L2<=>L1 transitions, reuse the
functionality for nested VMX, and drop the ucall hack that was fudging
around the lack of GPR switching on nVMX.
- Add a stress test to verify KVM doesn't clobber/drop #PF state, e.g. CR2,
across save/restore, including when L2 is active.
- Add a test to verify KVM_CREATE_VM accepts exactly what is reported by
KVM_CAP_VM_TYPES.
- Misc selftests fixes and cleanups