>>> On 04.10.16 at 09:34, <andrew.coop...@citrix.com> wrote: > 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.
Oh, of course. Sorry for the noise. But then the check added to emulate_privileged_op() fails to honor (virtual) CPL afaict. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
