[PATCH v4 4/6] powerpc/pseries: flush SLB contents on SLB MCE errors.
Mahesh J Salgaonkar
mahesh at linux.vnet.ibm.com
Thu Jun 28 21:11:48 AEST 2018
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 | 56 +++++++++++++++++++++++++
arch/powerpc/platforms/pseries/setup.c | 1
9 files changed, 121 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 50ed64fba4ae..cc00a7088cf3 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_flush_and_rebolt_realmode(void);
extern void slb_vmalloc_update(void);
extern void slb_set_size(u16 size);
diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index ffe7c71e1132..fe447e0d4140 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -108,6 +108,7 @@ struct machdep_calls {
/* Early exception handlers called in realmode */
int (*hmi_exception_early)(struct pt_regs *regs);
+ int (*machine_check_early)(struct pt_regs *regs);
/* Called during machine check exception to retrive fixup address. */
bool (*mce_check_early_recovery)(struct pt_regs *regs);
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index f283958129f2..0038596b7906 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -332,6 +332,9 @@ TRAMP_REAL_BEGIN(machine_check_pSeries)
machine_check_fwnmi:
SET_SCRATCH0(r13) /* save r13 */
EXCEPTION_PROLOG_0(PACA_EXMC)
+BEGIN_FTR_SECTION
+ b machine_check_pSeries_early
+END_FTR_SECTION_IFCLR(CPU_FTR_HVMODE)
machine_check_pSeries_0:
EXCEPTION_PROLOG_1(PACA_EXMC, KVMTEST_PR, 0x200)
/*
@@ -343,6 +346,45 @@ machine_check_pSeries_0:
TRAMP_KVM_SKIP(PACA_EXMC, 0x200)
+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 */
+
+ /* Move original SRR0 and SRR1 into the respective regs */
+ ld r9,_MSR(r1)
+ mtspr SPRN_SRR1,r9
+ ld r3,_NIP(r1)
+ mtspr SPRN_SRR0,r3
+ ld r9,_CTR(r1)
+ mtctr r9
+ ld r9,_XER(r1)
+ mtxer r9
+ ld r9,_LINK(r1)
+ mtlr r9
+ REST_GPR(0, r1)
+ REST_8GPRS(2, r1)
+ REST_GPR(10, r1)
+ ld r11,_CCR(r1)
+ mtcr r11
+ REST_GPR(11, r1)
+ REST_2GPRS(12, r1)
+ /* restore original r1. */
+ ld r1,GPR1(r1)
+ SET_SCRATCH0(r13) /* save r13 */
+ EXCEPTION_PROLOG_0(PACA_EXMC)
+ b machine_check_pSeries_0
+END_FTR_SECTION_IFCLR(CPU_FTR_HVMODE)
+
EXC_COMMON_BEGIN(machine_check_common)
/*
* Machine check is different because we use a different
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);
return handled;
}
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 66577cc66dc9..5b1813b98358 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -145,6 +145,12 @@ void slb_flush_and_rebolt(void)
get_paca()->slb_cache_ptr = 0;
}
+void slb_flush_and_rebolt_realmode(void)
+{
+ __slb_flush_and_rebolt();
+ get_paca()->slb_cache_ptr = 0;
+}
+
void slb_vmalloc_update(void)
{
unsigned long vflags;
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 48fbb41af5d1..ed548d40a9e1 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -417,7 +417,6 @@ static int opal_recover_mce(struct pt_regs *regs,
if (!(regs->msr & MSR_RI)) {
/* If MSR_RI isn't set, we cannot recover */
- pr_err("Machine check interrupt unrecoverable: MSR(RI=0)\n");
recovered = 0;
} else if (evt->disposition == MCE_DISPOSITION_RECOVERED) {
/* Platform corrected itself */
diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index 60db2ee511fb..3611db5dd583 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h
@@ -24,6 +24,7 @@ struct pt_regs;
extern int pSeries_system_reset_exception(struct pt_regs *regs);
extern int pSeries_machine_check_exception(struct pt_regs *regs);
+extern int pSeries_machine_check_realmode(struct pt_regs *regs);
#ifdef CONFIG_SMP
extern void smp_init_pseries(void);
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index e3bd849141de..ae08263daa24 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -333,6 +333,11 @@ static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
+static inline struct rtas_error_log *fwnmi_get_errlog(void)
+{
+ return (struct rtas_error_log *)local_paca->mce_data_buf;
+}
+
/*
* Get the error information for errors coming through the
* FWNMI vectors. The pt_regs' r3 will be updated to reflect
@@ -423,6 +428,35 @@ 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;
+
+ if (!rtas_error_extended(errp))
+ goto out;
+
+ 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)) {
+ /* Store the old slb content someplace. */
+ slb_flush_and_rebolt_realmode();
+ disposition = RTAS_DISP_FULLY_RECOVERED;
+ rtas_set_disposition_recovered(errp);
+ }
+
+out:
+ return disposition;
+}
+
/*
* Process MCE rtas errlog event.
*/
@@ -499,11 +533,31 @@ int pSeries_machine_check_exception(struct pt_regs *regs)
struct rtas_error_log *errp;
if (fwnmi_active) {
- errp = fwnmi_get_errinfo(regs);
fwnmi_release_errinfo();
+ errp = fwnmi_get_errlog();
if (errp && recover_mce(regs, errp))
return 1;
}
return 0;
}
+
+int pSeries_machine_check_realmode(struct pt_regs *regs)
+{
+ struct rtas_error_log *errp;
+ int disposition;
+
+ if (fwnmi_active) {
+ errp = fwnmi_get_errinfo(regs);
+ /*
+ * Call to fwnmi_release_errinfo() in real mode causes kernel
+ * to panic. Hence we will call it as soon as we go into
+ * virtual mode.
+ */
+ disposition = mce_handle_error(errp);
+ if (disposition == RTAS_DISP_FULLY_RECOVERED)
+ return 1;
+ }
+
+ return 0;
+}
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 60a067a6e743..249b02bc5c41 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -999,6 +999,7 @@ define_machine(pseries) {
.calibrate_decr = generic_calibrate_decr,
.progress = rtas_progress,
.system_reset_exception = pSeries_system_reset_exception,
+ .machine_check_early = pSeries_machine_check_realmode,
.machine_check_exception = pSeries_machine_check_exception,
#ifdef CONFIG_KEXEC_CORE
.machine_kexec = pSeries_machine_kexec,
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