On Mon, Sep 12, 2016 at 9:56 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > You should explicitly check that, if the > feature is set under Xen PV, then the MSR actually works as > advertised. This may require talking to the Xen folks to make sure > you're testing the right configuration. This is interesting. When running under Xen PV the kernel is allowed to read the real value of MSR_PLATFORM_INFO and see that CPUID faulting is supported. But as you suggested, writing to MSR_MISC_FEATURES_ENABLES doesn't actually enable CPUID faulting, at least not in any way that works. It's not obvious to me how to test this, because when this feature works, CPUID only faults in userspace, not in the kernel. Is there existing code somewhere that runs tests like this in userspace? - Kyle -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
