On Thu, Apr 13, 2017 at 05:18:17PM +1000, Nicholas Piggin wrote: > On Thu, 13 Apr 2017 16:27:34 +1000 > Michael Neuling <mi...@neuling.org> wrote: > > > On Thu, 2017-04-13 at 14:12 +1000, Benjamin Herrenschmidt wrote: > > > On Thu, 2017-04-13 at 09:28 +0530, Aneesh Kumar K.V wrote: > > > > > #endif > > > > > mtctr r12 > > > > > bctrl > > > > > +/* > > > > > + * cur_cpu_spec->cpu_restore would restore LPCR to a > > > > > + * sane value that is set at early boot time, > > > > > + * thereby clearing LPCR_UPRT. > > > > > + * LPCR_UPRT is required if we are running in Radix mode. > > > > > + * Set it here if that be the case. > > > > > + */ > > > > > +BEGIN_MMU_FTR_SECTION > > > > > + mfspr r3, SPRN_LPCR > > > > > + LOAD_REG_IMMEDIATE(r4, LPCR_UPRT) > > > > > + or r3, r3, r4 > > > > > + mtspr SPRN_LPCR, r3 > > > > > +END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX) > > > > > > We are probably better off saving the value somewhere during boot > > > and just "blasting" it whole back. > > > > We seem to touch LPCR in a bunch of places these days. Not sure when > > "sometimes > > during boot" should actually be. > > In the short term, what if we just save LPCR and restore it after calling > cpu_restore? As you say there are a lot of things that touch LPCR we're > not catching here.
In that case can we skip calling cpu_restore in the idle_exit path altogether and simply restore LPCR to the value that the thread had before executing stop ? > -- Thanks and Regards gautham.