From 703b1a7897d802c33bc03b0bcdd80cbc9d6a470d Mon Sep 17 00:00:00 2001
From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Date: Tue, 11 Sep 2018 19:57:00 +0530
Subject: [PATCH 2/7] powerpc/pseries: Flush SLB contents on SLB MCE errors.
References: bsc#1094244
Patch-mainline: v4.20-rc1
Git-commit: a43c1590426c44a5c6bbaf51b70a36a5c6d86914
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/ERAT errors.
[note: Define MAX_MCE_DEPTH
Defined in Linux 4.15-rc1 commit ba41e1e1ccb9771ce41a3b8e2121f95486e76ac9]
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michal Suchanek <msuchanek@suse.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/include/asm/exception-64s.h | 5 ++
arch/powerpc/include/asm/machdep.h | 1 +
arch/powerpc/include/asm/mce.h | 3 +
arch/powerpc/kernel/exceptions-64s.S | 129 +++++++++++++++++++++++++++++++
arch/powerpc/kernel/mce.c | 9 ++-
arch/powerpc/kernel/mce_power.c | 2 +-
arch/powerpc/platforms/powernv/opal.c | 2 +
arch/powerpc/platforms/powernv/setup.c | 11 +++
arch/powerpc/platforms/pseries/pseries.h | 1 +
arch/powerpc/platforms/pseries/ras.c | 60 +++++++++++++-
arch/powerpc/platforms/pseries/setup.c | 1 +
11 files changed, 218 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 87afb25be51a..6c4a487df1ce 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -54,6 +54,11 @@
#define EX_SIZE 13 /* size in u64 units */
+/*
+ * maximum recursive depth of MCE exceptions
+ */
+#define MAX_MCE_DEPTH 4
+
#define STF_ENTRY_BARRIER_SLOT \
STF_ENTRY_BARRIER_FIXUP_SECTION; \
nop; \
diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index ffe7c71e1132..a239f545d624 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);
+ long (*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/include/asm/mce.h b/arch/powerpc/include/asm/mce.h
index 190d69a7f701..4315a92adc37 100644
--- a/arch/powerpc/include/asm/mce.h
+++ b/arch/powerpc/include/asm/mce.h
@@ -212,4 +212,7 @@ extern void machine_check_print_event_info(struct machine_check_event *evt,
bool user_mode);
extern uint64_t get_mce_fault_addr(struct machine_check_event *evt);
+#ifdef CONFIG_PPC_BOOK3S_64
+void flush_and_reload_slb(void);
+#endif /* CONFIG_PPC_BOOK3S_64 */
#endif /* __ASM_PPC64_MCE_H__ */
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 02c78571198c..f2c070311336 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -276,6 +276,9 @@ 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)
/*
@@ -287,6 +290,103 @@ 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 */
+ lhz r11,PACA_IN_MCE(r13)
+ cmpwi r11,0 /* Are we in nested machine check */
+ bne 0f /* Yes, we are. */
+ /* First machine check entry */
+ ld r1,PACAMCEMERGSP(r13) /* Use MC emergency stack */
+0: subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */
+ addi r11,r11,1 /* increment paca->in_mce */
+ sth r11,PACA_IN_MCE(r13)
+ /* Limit nested MCE to level 4 to avoid stack overflow */
+ cmpwi r11,MAX_MCE_DEPTH
+ bgt 1f /* Check if we hit limit of 4 */
+ 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 */
+ ld r12,_MSR(r1)
+ andi. r11,r12,MSR_PR /* See if coming from user. */
+ bne 2f /* continue in V mode if we are. */
+
+ /*
+ * At this point we are not sure about what context we come from.
+ * We may be in the middle of switching stack. r1 may not be valid.
+ * Hence stay on emergency stack, call machine_check_exception and
+ * return from the interrupt.
+ * But before that, check if this is an un-recoverable exception.
+ * If yes, then stay on emergency stack and panic.
+ */
+ andi. r11,r12,MSR_RI
+ beq 1f
+
+ /*
+ * Check if we have successfully handled/recovered from error, if not
+ * then stay on emergency stack and panic.
+ */
+ cmpdi r3,0 /* see if we handled MCE successfully */
+ beq 1f /* if !handled then panic */
+
+ /* Stay on emergency stack and return from interrupt. */
+ LOAD_HANDLER(r10,mce_return)
+ mtspr SPRN_SRR0,r10
+ ld r10,PACAKMSR(r13)
+ mtspr SPRN_SRR1,r10
+ RFI_TO_KERNEL
+ b .
+
+1: LOAD_HANDLER(r10,unrecover_mce)
+ mtspr SPRN_SRR0,r10
+ ld r10,PACAKMSR(r13)
+ /*
+ * We are going down. But there are chances that we might get hit by
+ * another MCE during panic path and we may run into unstable state
+ * with no way out. Hence, turn ME bit off while going down, so that
+ * when another MCE is hit during panic path, hypervisor will
+ * power cycle the lpar, instead of getting into MCE loop.
+ */
+ li r3,MSR_ME
+ andc r10,r10,r3 /* Turn off MSR_ME */
+ mtspr SPRN_SRR1,r10
+ RFI_TO_KERNEL
+ b .
+
+ /* Move original SRR0 and SRR1 into the respective regs */
+2: 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
+ /* Decrement paca->in_mce. */
+ lhz r12,PACA_IN_MCE(r13)
+ subi r12,r12,1
+ sth r12,PACA_IN_MCE(r13)
+ 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
@@ -480,6 +580,35 @@ EXC_COMMON_BEGIN(unrecover_mce)
bl unrecoverable_exception
b 1b
+EXC_COMMON_BEGIN(mce_return)
+ /* Invoke machine_check_exception to print MCE event and return. */
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ bl machine_check_exception
+ 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
+ /* Decrement paca->in_mce. */
+ lhz r12,PACA_IN_MCE(r13)
+ subi r12,r12,1
+ sth r12,PACA_IN_MCE(r13)
+ REST_GPR(11, r1)
+ REST_2GPRS(12, r1)
+ /* restore original r1. */
+ ld r1,GPR1(r1)
+ RFI_TO_KERNEL
+ b .
EXC_REAL(data_access, 0x300, 0x80)
EXC_VIRT(data_access, 0x4300, 0x80, 0x300)
diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index f588951b171d..c5506ced46a0 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c
@@ -459,10 +459,11 @@ long machine_check_early(struct pt_regs *regs)
{
long handled = 0;
- __this_cpu_inc(irq_stat.mce_exceptions);
-
- if (cur_cpu_spec && cur_cpu_spec->machine_check_early)
- handled = cur_cpu_spec->machine_check_early(regs);
+ /*
+ * See if platform is capable of handling machine check.
+ */
+ if (ppc_md.machine_check_early)
+ handled = ppc_md.machine_check_early(regs);
return handled;
}
diff --git a/arch/powerpc/kernel/mce_power.c b/arch/powerpc/kernel/mce_power.c
index 10be4c8d3682..8e1e129fe2f1 100644
--- a/arch/powerpc/kernel/mce_power.c
+++ b/arch/powerpc/kernel/mce_power.c
@@ -30,7 +30,7 @@
/* flush SLBs and reload */
#ifdef CONFIG_PPC_BOOK3S_64
-static void flush_and_reload_slb(void)
+void flush_and_reload_slb(void)
{
/* Invalidate all SLBs */
slb_flush_all_realmode();
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 3c122d08b6c3..8e6cf5de690f 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -443,6 +443,8 @@ int opal_machine_check(struct pt_regs *regs)
struct machine_check_event evt;
int ret;
+ __this_cpu_inc(irq_stat.mce_exceptions);
+
if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
return 0;
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index f9f67edcefdc..ef88a5b6a222 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -443,6 +443,16 @@ 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,
@@ -454,6 +464,7 @@ 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
diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index c21ed7a95b65..0db8472264d7 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 long 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 a3613020cefb..8cb5eb3c63c2 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -27,6 +27,7 @@
#include <asm/machdep.h>
#include <asm/rtas.h>
#include <asm/firmware.h>
+#include <asm/mce.h>
#include "pseries.h"
@@ -507,6 +508,43 @@ 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);
+ u8 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 = mce_log->error_type;
+
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (disposition == RTAS_DISP_NOT_RECOVERED) {
+ switch (error_type) {
+ case MC_ERROR_TYPE_SLB:
+ case MC_ERROR_TYPE_ERAT:
+ /* Store the old slb content someplace. */
+ flush_and_reload_slb();
+ disposition = RTAS_DISP_FULLY_RECOVERED;
+ rtas_set_disposition_recovered(errp);
+ break;
+ default:
+ break;
+ }
+ }
+#endif
+
+out:
+ return disposition;
+}
+
/*
* Process MCE rtas errlog event.
*/
@@ -583,11 +621,31 @@ 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;
}
+
+long 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 ee60f5284e54..97883f332dc0 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -1003,6 +1003,7 @@ 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,
--
2.13.7