On Thu, 23 Aug 2018 14:13:13 +0530 Mahesh Jagannath Salgaonkar <mah...@linux.vnet.ibm.com> wrote:
> On 08/20/2018 05:04 PM, Nicholas Piggin wrote: > > On Sun, 19 Aug 2018 22:38:39 +0530 > > Mahesh J Salgaonkar <mah...@linux.vnet.ibm.com> wrote: > > > >> From: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com> > >> > >> Now that other platforms also implements real mode mce handler, > >> lets consolidate the code by sharing existing powernv machine check > >> early code. Rename machine_check_powernv_early to > >> machine_check_common_early and reuse the code. > >> > >> Signed-off-by: Mahesh Salgaonkar <mah...@linux.vnet.ibm.com> > >> --- > >> arch/powerpc/kernel/exceptions-64s.S | 155 > >> ++++++---------------------------- > >> 1 file changed, 28 insertions(+), 127 deletions(-) > >> > >> diff --git a/arch/powerpc/kernel/exceptions-64s.S > >> b/arch/powerpc/kernel/exceptions-64s.S > >> index 12f056179112..2f85a7baf026 100644 > >> --- a/arch/powerpc/kernel/exceptions-64s.S > >> +++ b/arch/powerpc/kernel/exceptions-64s.S > >> @@ -243,14 +243,13 @@ EXC_REAL_BEGIN(machine_check, 0x200, 0x100) > >> SET_SCRATCH0(r13) /* save r13 */ > >> EXCEPTION_PROLOG_0(PACA_EXMC) > >> BEGIN_FTR_SECTION > >> - b machine_check_powernv_early > >> + b machine_check_common_early > >> FTR_SECTION_ELSE > >> b machine_check_pSeries_0 > >> ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE) > >> EXC_REAL_END(machine_check, 0x200, 0x100) > >> EXC_VIRT_NONE(0x4200, 0x100) > >> -TRAMP_REAL_BEGIN(machine_check_powernv_early) > >> -BEGIN_FTR_SECTION > >> +TRAMP_REAL_BEGIN(machine_check_common_early) > >> EXCEPTION_PROLOG_1(PACA_EXMC, NOTEST, 0x200) > >> /* > >> * Register contents: > >> @@ -306,7 +305,9 @@ BEGIN_FTR_SECTION > >> /* Save r9 through r13 from EXMC save area to stack frame. */ > >> EXCEPTION_PROLOG_COMMON_2(PACA_EXMC) > >> mfmsr r11 /* get MSR value */ > >> +BEGIN_FTR_SECTION > >> ori r11,r11,MSR_ME /* turn on ME bit */ > >> +END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) > >> ori r11,r11,MSR_RI /* turn on RI bit */ > >> LOAD_HANDLER(r12, machine_check_handle_early) > >> 1: mtspr SPRN_SRR0,r12 > >> @@ -325,7 +326,6 @@ BEGIN_FTR_SECTION > >> andc r11,r11,r10 /* Turn off MSR_ME */ > >> b 1b > >> b . /* prevent speculative execution */ > >> -END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) > >> > >> TRAMP_REAL_BEGIN(machine_check_pSeries) > >> .globl machine_check_fwnmi > >> @@ -333,7 +333,7 @@ machine_check_fwnmi: > >> SET_SCRATCH0(r13) /* save r13 */ > >> EXCEPTION_PROLOG_0(PACA_EXMC) > >> BEGIN_FTR_SECTION > >> - b machine_check_pSeries_early > >> + b machine_check_common_early > >> END_FTR_SECTION_IFCLR(CPU_FTR_HVMODE) > >> machine_check_pSeries_0: > >> EXCEPTION_PROLOG_1(PACA_EXMC, KVMTEST_PR, 0x200) > >> @@ -346,103 +346,6 @@ 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 swithing 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 > >> @@ -541,6 +444,9 @@ EXC_COMMON_BEGIN(machine_check_handle_early) > >> bl machine_check_early > >> std r3,RESULT(r1) /* Save result */ > >> ld r12,_MSR(r1) > >> +BEGIN_FTR_SECTION > >> + b 4f > >> +END_FTR_SECTION_IFCLR(CPU_FTR_HVMODE) > >> > >> #ifdef CONFIG_PPC_P7_NAP > >> /* > >> @@ -564,10 +470,11 @@ EXC_COMMON_BEGIN(machine_check_handle_early) > >> */ > >> rldicl. r11,r12,4,63 /* See if MC hit while in HV mode. */ > >> beq 5f > >> - andi. r11,r12,MSR_PR /* See if coming from user. */ > >> +4: andi. r11,r12,MSR_PR /* See if coming from user. */ > >> bne 9f /* continue in V mode if we are. */ > >> > >> 5: > >> +BEGIN_FTR_SECTION > >> #ifdef CONFIG_KVM_BOOK3S_64_HANDLER > >> /* > >> * We are coming from kernel context. Check if we are coming from > >> @@ -578,6 +485,7 @@ EXC_COMMON_BEGIN(machine_check_handle_early) > >> cmpwi r11,0 /* Check if coming from guest */ > >> bne 9f /* continue if we are. */ > >> #endif > >> +END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) > > > > Put these inside the ifdef? > > > > > >> /* > >> * At this point we are not sure about what context we come from. > >> * Queue up the MCE event and return from the interrupt. > >> @@ -611,6 +519,7 @@ EXC_COMMON_BEGIN(machine_check_handle_early) > >> cmpdi r3,0 /* see if we handled MCE successfully */ > >> > >> beq 1b /* if !handled then panic */ > >> +BEGIN_FTR_SECTION > >> /* > >> * Return from MC interrupt. > >> * Queue up the MCE event so that we can log it later, while > >> @@ -619,10 +528,24 @@ EXC_COMMON_BEGIN(machine_check_handle_early) > >> bl machine_check_queue_event > >> MACHINE_CHECK_HANDLER_WINDUP > >> RFI_TO_USER_OR_KERNEL > >> +FTR_SECTION_ELSE > >> + /* > >> + * pSeries: Return from MC interrupt. Before that stay on emergency > >> + * stack and call machine_check_exception to log the MCE event. > >> + */ > >> + LOAD_HANDLER(r10,mce_return) > >> + mtspr SPRN_SRR0,r10 > >> + ld r10,PACAKMSR(r13) > >> + mtspr SPRN_SRR1,r10 > >> + RFI_TO_KERNEL > >> + b . > >> +ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE) > > > > Do you still need mce_return? Why can't you consolidate it as well? ... > > Hmm, okay so now I look back at patch 2, I don't think you should call > > machine_check_exception there. You're supposed to call > > machine_check_queue_event here and it will be handled by irq work. > > machine_check_queue_event does not handle RTAS mce event. Yes it would need a bit of work. > Also, we need > to call fwnmi_release_errinfo() as early as possible which is why I am > calling machine_check_exception() in mce_return path for pSeries. > Otherwise if we get another MCE before calling fwnmi_release_errinfo() > then lpar will get rebooted without any logs getting printed. I think you can call that in your early handler, but then defer the printing to the irq work. Although hmm, maybe that's less of a problem now we do nmi_enter in machine check exception so I think printk will use an NMI safe buffer. We have to be careful actually of soft irq state if we take a machine check in an un-reconciled state or in the middle of the irq replay code I'm not actually sure we do the right thing, but that would be a bug in existing code too. And we definitely have MSR[RI] vs DAR/DSISR bugs in existing code, sigh. I don't know... maybe just push what you have and we'll try to do some more fixes and cleanups on top of that. Thanks, Nick
