> From: Andrew Cooper [mailto:andrew.coop...@citrix.com] > Sent: Tuesday, February 27, 2018 3:11 AM > > On 26/02/18 11:25, Jan Beulich wrote: > >>>> On 20.02.18 at 12:58, <andrew.coop...@citrix.com> wrote: > >> If the CPU pipeline supports RDTSCP or RDPID, a guest can observe the > value in > >> MSR_TSC_AUX, irrespective of whether the relevant CPUID features are > >> advertised/hidden. > >> > >> At the moment, paravirt_ctxt_switch_to() only writes to MSR_TSC_AUX if > >> TSC_MODE_PVRDTSCP mode is enabled, but this is not the default mode. > >> Therefore, default PV guests can read the value from a previously > scheduled > >> HVM vcpu, or TSC_MODE_PVRDTSCP-enabled PV guest. > >> > >> Alter the PV path to always write to MSR_TSC_AUX, using 0 in the > common > >> case. > >> > >> To amortise overhead cost, introduce wrmsr_tsc_aux() which performs > a lazy > >> update of the MSR, and use this function consistently across the > codebase. > >> > >> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> > > Despite me continuing to think that RDTSCP and RDPID should be > > fully independent features, this being in line with the SDM: > > Acked-by: Jan Beulich <jbeul...@suse.com> > > Thanks. > > Given the important of this patch, I feel it is time to ping the VT-x > and SVM maintainers for their input. > > ~Andrew
Reviewed-by: Kevin Tian <kevin.t...@intel.com> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
