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powerpc/pseries: Flush SLB contents on SLB MCE errors.

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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.

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>
This commit is contained in:
Mahesh Salgaonkar 2018-09-11 19:57:00 +05:30 committed by Michael Ellerman
parent 04fce21c9d
commit a43c159042
10 changed files with 213 additions and 6 deletions
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1
arch/powerpc/include/asm/machdep.h
View File

@ -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);

3
arch/powerpc/include/asm/mce.h
View File

@ -210,4 +210,7 @@ extern void release_mce_event(void);
extern void machine_check_queue_event(void);
extern void machine_check_print_event_info(struct machine_check_event *evt,
bool user_mode);
#ifdef CONFIG_PPC_BOOK3S_64
void flush_and_reload_slb(void);
#endif /* CONFIG_PPC_BOOK3S_64 */
#endif /* __ASM_PPC64_MCE_H__ */

129
arch/powerpc/kernel/exceptions-64s.S
View File

@ -331,6 +331,9 @@ 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)
/*
@ -342,6 +345,103 @@ 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
@ -535,6 +635,35 @@ 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)

9
arch/powerpc/kernel/mce.c
View File

@ -488,10 +488,11 @@ 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;
}

2
arch/powerpc/kernel/mce_power.c
View File

@ -60,7 +60,7 @@ static unsigned long addr_to_pfn(struct pt_regs *regs, unsigned long addr)
/* 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();

2
arch/powerpc/platforms/powernv/opal.c
View File

@ -578,6 +578,8 @@ int opal_machine_check(struct pt_regs *regs)
{
struct machine_check_event evt;
__this_cpu_inc(irq_stat.mce_exceptions);
if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
return 0;

11
arch/powerpc/platforms/powernv/setup.c
View File

@ -437,6 +437,16 @@ 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,
@ -448,6 +458,7 @@ 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

1
arch/powerpc/platforms/pseries/pseries.h
View File

@ -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);

60
arch/powerpc/platforms/pseries/ras.c
View File

@ -27,6 +27,7 @@
#include <asm/machdep.h>
#include <asm/rtas.h>
#include <asm/firmware.h>
#include <asm/mce.h>
#include "pseries.h"
@ -522,6 +523,43 @@ 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.
*/
@ -598,11 +636,31 @@ 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;
}

1
arch/powerpc/platforms/pseries/setup.c
View File

@ -1017,6 +1017,7 @@ 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,