On 17/09/2019 07:17, Jan Beulich wrote: > PCID validly depends on LM, as it can be enabled in Long Mode only. > INVPCID, otoh, can be used not only without PCID enabled, but also > outside of Long Mode altogether. In both cases its functionality is > simply restricted to PCID 0, which is sort of expected as no other PCID > can be activated there. > > Signed-off-by: Jan Beulich <jbeul...@suse.com> > Reviewed-by: Roger Pau Monné <roger....@citrix.com> > > --- a/xen/tools/gen-cpuid.py > +++ b/xen/tools/gen-cpuid.py > @@ -218,10 +218,6 @@ def crunch_numbers(state): > # > # SSE4_2: [POPCNT] > > - # The INVPCID instruction depends on PCID infrastructure being > - # available. > - PCID: [INVPCID],
I take it you haven't tried running a shadow guest with this change in place. For !EPT, we clear ENABLE_INVPCID so the instruction will #UD within the guest. We could in principle allow the use of INVPCID with shadow guests, but that would involve teaching Xen how to cope with VMEXIT_REASON_INVPCID (which is predicated on INVLPG exiting) and wire the flush back into the shadow logic. Perhaps the comment could be a little clearer, but it is no accident that dependency is in place. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
