On Wed, 2 Nov 2016 13:54:43 +0530 Mahesh J Salgaonkar <mah...@linux.vnet.ibm.com> wrote:
> On 2016-11-02 17:57:01 Wed, Nicholas Piggin wrote: > > On Wed, 2 Nov 2016 11:34:59 +0530 > > Mahesh Jagannath Salgaonkar <mah...@linux.vnet.ibm.com> wrote: > > > > > On 10/13/2016 07:47 AM, Nicholas Piggin wrote: > > > > This patch does a couple of things. First of all, powernv immediately > > > > explodes when running a relocated kernel, because the system reset > > > > exception for handling sleeps does not do correct relocated branches. > > > > > > > > Secondly, the sleep handling code trashes the condition and cfar > > > > registers, which we would like to preserve for debugging purposes (for > > > > non-sleep case exception). > > > > > > > > This patch changes the exception to use the standard format that saves > > > > registers before any tests or branches are made. It adds the test for > > > > idle-wakeup as an "extra" to break out of the normal exception path. > > > > Then it branches to a relocated idle handler that calls the various > > > > idle handling functions. > > > > > > > > After this patch, POWER8 CPU simulator now boots powernv kernel that is > > > > running at non-zero. > > > > > > > > Cc: Balbir Singh <bsinghar...@gmail.com> > > > > Cc: Shreyas B. Prabhu <shre...@linux.vnet.ibm.com> > > > > Cc: Gautham R. Shenoy <e...@linux.vnet.ibm.com> > > > > Signed-off-by: Nicholas Piggin <npig...@gmail.com> > > > > --- > > > > arch/powerpc/include/asm/exception-64s.h | 16 ++++++++++ > > > > arch/powerpc/kernel/exceptions-64s.S | 50 > > > > ++++++++++++++++++-------------- > > > > 2 files changed, 45 insertions(+), 21 deletions(-) > > > > > > > > diff --git a/arch/powerpc/include/asm/exception-64s.h > > > > b/arch/powerpc/include/asm/exception-64s.h > > > > index 2e4e7d8..84d49b1 100644 > > > > --- a/arch/powerpc/include/asm/exception-64s.h > > > > +++ b/arch/powerpc/include/asm/exception-64s.h > > > > @@ -93,6 +93,10 @@ > > > > ld reg,PACAKBASE(r13); /* get high part of &label */ > > > > \ > > > > ori reg,reg,(FIXED_SYMBOL_ABS_ADDR(label))@l; > > > > > > > > +#define __LOAD_HANDLER(reg, label) > > > > \ > > > > + ld reg,PACAKBASE(r13); > > > > \ > > > > + ori reg,reg,(ABS_ADDR(label))@l; > > > > + > > > > /* Exception register prefixes */ > > > > #define EXC_HV H > > > > #define EXC_STD > > > > @@ -208,6 +212,18 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) > > > > #define kvmppc_interrupt kvmppc_interrupt_pr > > > > #endif > > > > > > > > +#ifdef CONFIG_RELOCATABLE > > > > +#define BRANCH_TO_COMMON(reg, label) > > > > \ > > > > + __LOAD_HANDLER(reg, label); > > > > \ > > > > + mtctr reg; > > > > \ > > > > + bctr > > > > + > > > > +#else > > > > +#define BRANCH_TO_COMMON(reg, label) > > > > \ > > > > + b label > > > > + > > > > +#endif > > > > + > > > > #define __KVM_HANDLER_PROLOG(area, n) > > > > \ > > > > BEGIN_FTR_SECTION_NESTED(947) > > > > \ > > > > ld r10,area+EX_CFAR(r13); > > > > \ > > > > diff --git a/arch/powerpc/kernel/exceptions-64s.S > > > > b/arch/powerpc/kernel/exceptions-64s.S > > > > index 08992f8..e680e84 100644 > > > > --- a/arch/powerpc/kernel/exceptions-64s.S > > > > +++ b/arch/powerpc/kernel/exceptions-64s.S > > > > @@ -95,19 +95,35 @@ __start_interrupts: > > > > /* No virt vectors corresponding with 0x0..0x100 */ > > > > EXC_VIRT_NONE(0x4000, 0x4100) > > > > > > > > -EXC_REAL_BEGIN(system_reset, 0x100, 0x200) > > > > - SET_SCRATCH0(r13) > > > > + > > > > #ifdef CONFIG_PPC_P7_NAP > > > > -BEGIN_FTR_SECTION > > > > - /* Running native on arch 2.06 or later, check if we are > > > > - * waking up from nap/sleep/winkle. > > > > + /* > > > > + * If running native on arch 2.06 or later, check if we are > > > > waking up > > > > + * from nap/sleep/winkle, and branch to idle handler. > > > > */ > > > > - mfspr r13,SPRN_SRR1 > > > > - rlwinm. r13,r13,47-31,30,31 > > > > - beq 9f > > > > +#define IDLETEST(n) > > > > \ > > > > + BEGIN_FTR_SECTION ; > > > > \ > > > > + mfspr r10,SPRN_SRR1 ; > > > > \ > > > > + rlwinm. r10,r10,47-31,30,31 ; > > > > \ > > > > + beq- 1f ; > > > > \ > > > > + cmpwi cr3,r10,2 ; > > > > \ > > > > + BRANCH_TO_COMMON(r10, system_reset_idle_common) ; > > > > \ > > > > +1: > > > > \ > > > > + END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206) > > > > +#else > > > > +#define IDLETEST NOTEST > > > > +#endif > > > > > > > > - cmpwi cr3,r13,2 > > > > - GET_PACA(r13) > > > > +EXC_REAL_BEGIN(system_reset, 0x100, 0x200) > > > > + SET_SCRATCH0(r13) > > > > + EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, system_reset_common, > > > > EXC_STD, > > > > + IDLETEST, 0x100) > > > > > > Very sorry for late review. On arch 2.07 and less if we wakeup from > > > winkle then last bit of HSPGR0 would be set to 1. Hence before we access > > > paca we need to fix it by clearing that bit and that is done in > > > pnv_restore_hyp_resource(). But with this patch, we would end up there > > > after going through EXCEPTION_PROLOG_PSERIES(). This macro gets the paca > > > using GET_PACA(r13) and all the EXCEPTION_PROLOG_* starts > > > using/accessing r13/paca without fixing it. Wouldn't this break things > > > badly on arch 2.07 and less ? Am I missing anything ? > > > > Arg, that's a stupid bug :( Thanks for catching it. > > > > Would something like the following do the trick, do you think? I obviously > > was not reaching winkle state in my testing. > > Yup, that will work. Okay, I'll work with that. What's the best way to make a P8 do winkle sleeps? Thanks, Nick
