On 04/10/2016 08:25, Jan Beulich wrote: >>>> On 04.10.16 at 00:38, <m...@kylehuey.com> wrote: >> rr (http://rr-project.org/), a Linux userspace record-and-replay reverse- >> execution debugger, would like to trap and emulate the CPUID instruction. >> This would allow us to a) mask away certain hardware features that rr does >> not support (e.g. RDRAND) and b) enable trace portability across machines >> by providing constant results. Patches for support in the Linux kernel are in >> flight, and we'd like to be able to use this feature on virtualized Linux >> instances as well. >> >> On HVM guests, the cpuid triggers a vm exit, so we can check the emulated >> faulting state in vmx_do_cpuid and inject a GP(0) if CPL > 0. > Why for CPL > 0 only? I don't think hardware CPUID faulting is CPL > sensitive.
CPUID Faulting is CPL sensitive. Otherwise Xen have a hard time executing cpuid instructions itself. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
