On Thu, 12 Jul 2018 15:41:13 +0200
Michal Suchánek <msucha...@suse.de> wrote:
> 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)?
Sorry, some emails fell through the cracks. Yes exactly like this would
be good. If you can add a quick changelog and SOB, and
Reviewed-by: Nicholas Piggin <npig...@gmail.com>
Thanks,
Nick
>
> 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
