[PATCH v8 5/5] powernv/pseries: consolidate code for mce early handling.
Nicholas Piggin
npiggin at gmail.com
Mon Aug 20 21:34:45 AEST 2018
On Sun, 19 Aug 2018 22:38:39 +0530
Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com> wrote:
> From: Mahesh Salgaonkar <mahesh at 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 <mahesh at 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.
I think when you do that more of this code should fall out and be
consolidated. Sorry for not picking that up earlier.
Thanks,
Nick
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