[PATCH v5 5/7] powerpc/pseries: flush SLB contents on SLB MCE errors.
Michal Suchánek
msuchanek at suse.de
Tue Jul 3 20:37:58 AEST 2018
On Tue, 3 Jul 2018 08:08:14 +1000
Nicholas Piggin <npiggin at gmail.com> wrote:
> On Mon, 02 Jul 2018 11:17:06 +0530
> Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com> wrote:
>
> > From: Mahesh Salgaonkar <mahesh at 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 <mahesh at 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?
Code sharing is nice but if we envision this going to stable kernels
butchering the existing handler is going to be a nightmare. The code is
quite a bit different between kernel versions.
This code as is requires the bit that introduces
EXCEPTION_PROLOG_COMMON_1 and then should work on Linux 3.14+
Thanks
Michal
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