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
