On 06/08/2018 07:18 AM, Nicholas Piggin wrote:
> On Thu, 07 Jun 2018 22:58:55 +0530
> Mahesh J Salgaonkar <mah...@linux.vnet.ibm.com> wrote:
>
>> From: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com>
>>
>> If we get a machine check exceptions due to SLB errors then dump the
>> current SLB contents which will be very much helpful in debugging the
>> root cause of SLB errors. On pseries, as of today system crashes on 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. This patch
>> fixes that also.
>
> So pseries never flushed SLB and reloaded in response to multi hit
> errors? This seems like quite a good improvement then. I like
> dumping SLB too.
>
> It's a bit annoying we can't share the same code with xmon really,
> that's okay but I just suggest commenting them both if you take a
> copy like this with a note to keep them in synch if you re-post
> the series.
>
>>
>> With this patch the console will log SLB contents like below on SLB MCE
>> errors:
>>
>> [ 822.711728] slb contents:
>
> Suggest keeping the same format as the xmon dump (in particular
> CPU number, even though it's probably printed elsewhere in the MCE
> message it doesn't hurt.
Sure will do that and repost.
Thanks,
-Mahesh.
>
> Reviewed-by: Nicholas Piggin <npig...@gmail.com>
>
> Thanks,
> Nick
>
>> [ 822.711730] 00 c000000008000000 400ea1b217000500
>> [ 822.711731] 1T ESID= c00000 VSID= ea1b217 LLP:100
>> [ 822.711732] 01 d000000008000000 400d43642f000510
>> [ 822.711733] 1T ESID= d00000 VSID= d43642f LLP:110
>> [ 822.711734] 09 f000000008000000 400a86c85f000500
>> [ 822.711736] 1T ESID= f00000 VSID= a86c85f LLP:100
>> [ 822.711737] 10 00007f0008000000 400d1f26e3000d90
>> [ 822.711738] 1T ESID= 7f VSID= d1f26e3 LLP:110
>> [ 822.711739] 11 0000000018000000 000e3615f520fd90
>> [ 822.711740] 256M ESID= 1 VSID= e3615f520f LLP:110
>> [ 822.711740] 12 d000000008000000 400d43642f000510
>> [ 822.711741] 1T ESID= d00000 VSID= d43642f LLP:110
>> [ 822.711742] 13 d000000008000000 400d43642f000510
>> [ 822.711743] 1T ESID= d00000 VSID= d43642f LLP:110
>>
>>
>> Suggested-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
>> Suggested-by: Michael Ellerman <m...@ellerman.id.au>
>> Signed-off-by: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/include/asm/book3s/64/mmu-hash.h | 1 +
>> arch/powerpc/mm/slb.c | 35
>> +++++++++++++++++++++++++
>> arch/powerpc/platforms/pseries/ras.c | 29 ++++++++++++++++++++-
>> 3 files changed, 64 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>> b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>> index 50ed64fba4ae..c0da68927235 100644
>> --- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>> +++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
>> @@ -487,6 +487,7 @@ extern void hpte_init_native(void);
>>
>> extern void slb_initialize(void);
>> extern void slb_flush_and_rebolt(void);
>> +extern void slb_dump_contents(void);
>>
>> extern void slb_vmalloc_update(void);
>> extern void slb_set_size(u16 size);
>> diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
>> index 66577cc66dc9..799aa117cec3 100644
>> --- a/arch/powerpc/mm/slb.c
>> +++ b/arch/powerpc/mm/slb.c
>> @@ -145,6 +145,41 @@ void slb_flush_and_rebolt(void)
>> get_paca()->slb_cache_ptr = 0;
>> }
>>
>> +void slb_dump_contents(void)
>> +{
>> + int i;
>> + unsigned long e, v;
>> + unsigned long llp;
>> +
>> + pr_err("slb contents:\n");
>> + for (i = 0; i < mmu_slb_size; i++) {
>> + asm volatile("slbmfee %0,%1" : "=r" (e) : "r" (i));
>> + asm volatile("slbmfev %0,%1" : "=r" (v) : "r" (i));
>> +
>> + if (!e && !v)
>> + continue;
>> +
>> + pr_err("%02d %016lx %016lx", i, e, v);
>> +
>> + if (!(e & SLB_ESID_V)) {
>> + pr_err("\n");
>> + continue;
>> + }
>> + llp = v & SLB_VSID_LLP;
>> + if (v & SLB_VSID_B_1T) {
>> + pr_err(" 1T ESID=%9lx VSID=%13lx LLP:%3lx\n",
>> + GET_ESID_1T(e),
>> + (v & ~SLB_VSID_B) >> SLB_VSID_SHIFT_1T,
>> + llp);
>> + } else {
>> + pr_err(" 256M ESID=%9lx VSID=%13lx LLP:%3lx\n",
>> + GET_ESID(e),
>> + (v & ~SLB_VSID_B) >> SLB_VSID_SHIFT,
>> + llp);
>> + }
>> + }
>> +}
>> +
>> void slb_vmalloc_update(void)
>> {
>> unsigned long vflags;
>> diff --git a/arch/powerpc/platforms/pseries/ras.c
>> b/arch/powerpc/platforms/pseries/ras.c
>> index 2edc673be137..e56759d92356 100644
>> --- a/arch/powerpc/platforms/pseries/ras.c
>> +++ b/arch/powerpc/platforms/pseries/ras.c
>> @@ -422,6 +422,31 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
>> return 0; /* need to perform reset */
>> }
>>
>> +static int mce_handle_error(struct rtas_error_log *errp)
>> +{
>> + struct pseries_errorlog *pseries_log;
>> + struct pseries_mc_errorlog *mce_log;
>> + int disposition = rtas_error_disposition(errp);
>> + uint8_t error_type;
>> +
>> + pseries_log = get_pseries_errorlog(errp, PSERIES_ELOG_SECT_ID_MCE);
>> + if (pseries_log == NULL)
>> + goto out;
>> +
>> + mce_log = (struct pseries_mc_errorlog *)pseries_log->data;
>> + error_type = rtas_mc_error_type(mce_log);
>> +
>> + if ((disposition == RTAS_DISP_NOT_RECOVERED) &&
>> + (error_type == PSERIES_MC_ERROR_TYPE_SLB)) {
>> + slb_dump_contents();
>> + slb_flush_and_rebolt();
>> + disposition = RTAS_DISP_FULLY_RECOVERED;
>> + }
>> +
>> +out:
>> + return disposition;
>> +}
>> +
>> /*
>> * See if we can recover from a machine check exception.
>> * This is only called on power4 (or above) and only via
>> @@ -434,7 +459,9 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
>> static int recover_mce(struct pt_regs *regs, struct rtas_error_log *err)
>> {
>> int recovered = 0;
>> - int disposition = rtas_error_disposition(err);
>> + int disposition;
>> +
>> + disposition = mce_handle_error(err);
>>
>> if (!(regs->msr & MSR_RI)) {
>> /* If MSR_RI isn't set, we cannot recover */
>>
>
