On Wed, Sep 14, 2016 at 6:17 PM, Andy Lutomirski <l...@amacapital.net> wrote: > On Wed, Sep 14, 2016 at 3:03 PM, Kyle Huey <m...@kylehuey.com> wrote: >> On Wed, Sep 14, 2016 at 2:35 PM, Dave Hansen >> <dave.han...@linux.intel.com> wrote: >>> On 09/14/2016 02:01 PM, Kyle Huey wrote: > >>> Is any of this useful to optimize away at compile-time? We have config >>> options for when we're running as a guest, and this seems like a feature >>> that isn't available when running on bare metal. >> >> On the contrary, this is only available when we're on bare metal. >> Neither Xen nor KVM virtualize CPUID faulting (although KVM correctly >> suppresses MSR_PLATFORM_INFO's report of support for it). > > KVM could easily support this. If rr starts using it, I think KVM > *should* add support, possibly even for older CPUs that don't support > the feature in hardware. > > It's too bad that x86 doesn't give us the instruction bytes on a > fault. Otherwise we could lazily switch this feature.
We are *very* interested in having KVM and Xen support virtualization of this feature. I am planning to work on KVM after I get this series of patches in :) - Kyle