On Tue, 3 Jul 2018 08:08:14 +1000 "Nicholas Piggin" <npig...@gmail.com> wrote:
> On Mon, 02 Jul 2018 11:17:06 +0530 > Mahesh J Salgaonkar <mah...@linux.vnet.ibm.com> wrote: > > > From: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com> > > > > On pseries, as of today system crashes if we get a machine check > > exceptions due to SLB errors. These are soft errors and can be > > fixed by flushing the SLBs so the kernel can continue to function > > instead of system crash. We do this in real mode before turning on > > MMU. Otherwise we would run into nested machine checks. This patch > > now fetches the rtas error log in real mode and flushes the SLBs on > > SLB errors. > > > > Signed-off-by: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com> > > --- > > arch/powerpc/include/asm/book3s/64/mmu-hash.h | 1 > > arch/powerpc/include/asm/machdep.h | 1 > > arch/powerpc/kernel/exceptions-64s.S | 42 > > +++++++++++++++++++++ arch/powerpc/kernel/mce.c > > | 16 +++++++- arch/powerpc/mm/slb.c | > > 6 +++ arch/powerpc/platforms/powernv/opal.c | 1 > > arch/powerpc/platforms/pseries/pseries.h | 1 > > arch/powerpc/platforms/pseries/ras.c | 51 > > +++++++++++++++++++++++++ > > arch/powerpc/platforms/pseries/setup.c | 1 9 files > > changed, 116 insertions(+), 4 deletions(-) > > > > +TRAMP_REAL_BEGIN(machine_check_pSeries_early) > > +BEGIN_FTR_SECTION > > + EXCEPTION_PROLOG_1(PACA_EXMC, NOTEST, 0x200) > > + mr r10,r1 /* Save r1 */ > > + ld r1,PACAMCEMERGSP(r13) /* Use MC emergency > > stack */ > > + subi r1,r1,INT_FRAME_SIZE /* alloc stack > > frame */ > > + mfspr r11,SPRN_SRR0 /* Save SRR0 */ > > + mfspr r12,SPRN_SRR1 /* Save SRR1 */ > > + EXCEPTION_PROLOG_COMMON_1() > > + EXCEPTION_PROLOG_COMMON_2(PACA_EXMC) > > + EXCEPTION_PROLOG_COMMON_3(0x200) > > + addi r3,r1,STACK_FRAME_OVERHEAD > > + BRANCH_LINK_TO_FAR(machine_check_early) /* Function call > > ABI */ > > Is there any reason you can't use the existing > machine_check_powernv_early code to do all this? > > > diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c > > index efdd16a79075..221271c96a57 100644 > > --- a/arch/powerpc/kernel/mce.c > > +++ b/arch/powerpc/kernel/mce.c > > @@ -488,9 +488,21 @@ long machine_check_early(struct pt_regs *regs) > > { > > long handled = 0; > > > > - __this_cpu_inc(irq_stat.mce_exceptions); > > + /* > > + * For pSeries we count mce when we go into virtual mode > > machine > > + * check handler. Hence skip it. Also, We can't access per > > cpu > > + * variables in real mode for LPAR. > > + */ > > + if (early_cpu_has_feature(CPU_FTR_HVMODE)) > > + __this_cpu_inc(irq_stat.mce_exceptions); > > > > - if (cur_cpu_spec && cur_cpu_spec->machine_check_early) > > + /* > > + * See if platform is capable of handling machine check. > > + * Otherwise fallthrough and allow CPU to handle this > > machine check. > > + */ > > + if (ppc_md.machine_check_early) > > + handled = ppc_md.machine_check_early(regs); > > + else if (cur_cpu_spec && cur_cpu_spec->machine_check_early) > > handled = > > cur_cpu_spec->machine_check_early(regs); > > Would be good to add a powernv ppc_md handler which does the > cur_cpu_spec->machine_check_early() call now that other platforms are > calling this code. Because those aren't valid as a fallback call, but > specific to powernv. > Something like this (untested)? Subject: [PATCH] powerpc/powernv: define platform MCE handler. --- arch/powerpc/kernel/mce.c | 3 --- arch/powerpc/platforms/powernv/setup.c | 11 +++++++++++ 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c index 221271c96a57..ae17d8aa60c4 100644 --- a/arch/powerpc/kernel/mce.c +++ b/arch/powerpc/kernel/mce.c @@ -498,12 +498,9 @@ long machine_check_early(struct pt_regs *regs) /* * See if platform is capable of handling machine check. - * Otherwise fallthrough and allow CPU to handle this machine check. */ if (ppc_md.machine_check_early) handled = ppc_md.machine_check_early(regs); - else if (cur_cpu_spec && cur_cpu_spec->machine_check_early) - handled = cur_cpu_spec->machine_check_early(regs); return handled; } diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c index f96df0a25d05..b74c93bc2e55 100644 --- a/arch/powerpc/platforms/powernv/setup.c +++ b/arch/powerpc/platforms/powernv/setup.c @@ -431,6 +431,16 @@ static unsigned long pnv_get_proc_freq(unsigned int cpu) return ret_freq; } +static long pnv_machine_check_early(struct pt_regs *regs) +{ + long handled = 0; + + if (cur_cpu_spec && cur_cpu_spec->machine_check_early) + handled = cur_cpu_spec->machine_check_early(regs); + + return handled; +} + define_machine(powernv) { .name = "PowerNV", .probe = pnv_probe, @@ -442,6 +452,7 @@ define_machine(powernv) { .machine_shutdown = pnv_shutdown, .power_save = NULL, .calibrate_decr = generic_calibrate_decr, + .machine_check_early = pnv_machine_check_early, #ifdef CONFIG_KEXEC_CORE .kexec_cpu_down = pnv_kexec_cpu_down, #endif -- 2.13.7