On Tue, Jul 15, 2014 at 08:44:39AM -0700, Andy Lutomirski wrote: > On Tue, Jul 15, 2014 at 8:38 AM, Konrad Rzeszutek Wilk > <konrad.wilk@xxxxxxxxxx> wrote: > > On Tue, Jul 15, 2014 at 08:26:41AM -0700, Andy Lutomirski wrote: > >> Xen doesn't call start_secondary. > > > > Duh! > >> > >> Cc: stable@xxxxxxxxxxxxxxx > >> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx> > >> --- > >> > >> espfix still doesn't seem to work on Xen (it goes boom in some way that > >> I don't understand right now), but initializing all CPUs instead of just > >> one of them seems like a good start. > >> > >> ISTM the right fix is probably to shove the espfix logic into > >> native_iret and to tweak the paravirt logic so that native_iret always > >> gets invoked. I suspect that Xen will need its own implementation of > >> espfix64 in the hypervisor and that, ultimately, someone may want to > >> stop initializing espfix64 at all on Xen guests. > > > > I think just disallowing would be preferrable. > > Disabling what? > > Sorry, my flu-addled brain needs more clarity. I'm currently working > on a patch on top of this one to move all of the espfix64 invocation > logic into native_iret, which will have the effect of preventing it > from being used on Xen. > > Is that what you mean? Yes. I presume the logic to deal with the bits losing information has to be dealt in the Xen case somehow. Peter asked whether the Xen IRET handles a 16-bit stack segment - and if it restores all of the RSP then we are OK. I don't have yet that information and my brain is a in low-power right now (-ENOSLEEP). -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html