On Mon, 20 Aug 2018, Jinpu Wang wrote: > On Sat, Aug 18, 2018 at 2:50 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > > > On Fri, 17 Aug 2018, Greg Kroah-Hartman wrote: > > > On Fri, Aug 17, 2018 at 02:39:00PM +0200, Jinpu Wang wrote: > > > > > > > > I found the problem, CONFIG_HOTPLUG_SMT is enable due to CONFIG_SMP, > > > > but I did explicitly enable CONFIG_HOTPLUG_CPU. > > > > > > > > That's why the smt dir is missing, and kernel panic when I boot with > > > > 'nosmt' or 'l1tf=full' probably also other combination. > > > > > > > > With CONFIG_HOTPLUG_CPU=y, it works fine so far. > > > > > > So do we need a new configuration dependancy here to resolve this > > > problem? Why is this not an issue in Linus's tree? > > > > That's probably the same problem on Linus tree. Have not tested it yet > > though. I'll have a look. > > > > Thanks, > > > > tglx > > > Yeah, it's the same problem on Linus tree. > > Probably makes sense to do the following, I can sent a formal patch if > you think it's right thing to do: > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index b0312f8..8a52f0b 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -188,7 +188,7 @@ config X86 > select HAVE_SYSCALL_TRACEPOINTS > select HAVE_UNSTABLE_SCHED_CLOCK > select HAVE_USER_RETURN_NOTIFIER > - select HOTPLUG_SMT if SMP > + select HOTPLUG_SMT if SMP && HOTPLUG_CPU That works, but we might as well force 'select HOTPLUG_CPU if SMP' so the L1TF mitigations are functional. Sigh.... Thanks, tglx
