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. 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 */ >