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. 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. Thanks, -Mahesh.
