* [RFC][PATCH 0/2] powerpc/pseries machine check reentrancy fixes
@ 2016-08-10 10:46 Nicholas Piggin
2016-08-10 10:48 ` [PATCH 1/2] powerpc/pseries: PACA save area fix for general exception vs MCE Nicholas Piggin
2016-08-10 10:48 ` [PATCH 2/2] powerpc/pseries: PACA save area fix for MCE " Nicholas Piggin
0 siblings, 2 replies; 4+ messages in thread
From: Nicholas Piggin @ 2016-08-10 10:46 UTC (permalink / raw)
To: linuxppc-dev
Cc: Nicholas Piggin, Mahesh Salgaonkar, Shreyas B . Prabhu, Stewart Smith
I noticed a couple of potential issues with MCE handling. I
haven't been able to test this yet, but I would like to get
some second opinions on it. I know a few people have been looking
at the MCE handler recently.
Thanks,
Nick
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 1/2] powerpc/pseries: PACA save area fix for general exception vs MCE
2016-08-10 10:46 [RFC][PATCH 0/2] powerpc/pseries machine check reentrancy fixes Nicholas Piggin
@ 2016-08-10 10:48 ` Nicholas Piggin
2016-08-11 6:45 ` Mahesh Jagannath Salgaonkar
2016-08-10 10:48 ` [PATCH 2/2] powerpc/pseries: PACA save area fix for MCE " Nicholas Piggin
1 sibling, 1 reply; 4+ messages in thread
From: Nicholas Piggin @ 2016-08-10 10:48 UTC (permalink / raw)
To: linuxppc-dev
Cc: Nicholas Piggin, Mahesh Salgaonkar, Shreyas B . Prabhu, Stewart Smith
MCE must not use PACA_EXGEN. When a general exception enables MSR_RI,
that means SPRN_SRR[01] and SPRN_SPRG are no longer used. However the
PACA save area is still in use.
---
arch/powerpc/kernel/exceptions-64s.S | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 694def6..4174c4e 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -984,14 +984,14 @@ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_RADIX)
machine_check_common:
mfspr r10,SPRN_DAR
- std r10,PACA_EXGEN+EX_DAR(r13)
+ std r10,PACA_EXMC+EX_DAR(r13)
mfspr r10,SPRN_DSISR
- stw r10,PACA_EXGEN+EX_DSISR(r13)
+ stw r10,PACA_EXMC+EX_DSISR(r13)
EXCEPTION_PROLOG_COMMON(0x200, PACA_EXMC)
FINISH_NAP
RECONCILE_IRQ_STATE(r10, r11)
- ld r3,PACA_EXGEN+EX_DAR(r13)
- lwz r4,PACA_EXGEN+EX_DSISR(r13)
+ ld r3,PACA_EXMC+EX_DAR(r13)
+ lwz r4,PACA_EXMC+EX_DSISR(r13)
std r3,_DAR(r1)
std r4,_DSISR(r1)
bl save_nvgprs
--
2.8.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] powerpc/pseries: PACA save area fix for MCE vs MCE
2016-08-10 10:46 [RFC][PATCH 0/2] powerpc/pseries machine check reentrancy fixes Nicholas Piggin
2016-08-10 10:48 ` [PATCH 1/2] powerpc/pseries: PACA save area fix for general exception vs MCE Nicholas Piggin
@ 2016-08-10 10:48 ` Nicholas Piggin
1 sibling, 0 replies; 4+ messages in thread
From: Nicholas Piggin @ 2016-08-10 10:48 UTC (permalink / raw)
To: linuxppc-dev
Cc: Nicholas Piggin, Mahesh Salgaonkar, Shreyas B . Prabhu, Stewart Smith
MCE must not enable MSR_RI until PACA_EXMC is no longer being used.
---
arch/powerpc/kernel/exceptions-64s.S | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 4174c4e..e20ad27 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -500,7 +500,23 @@ machine_check_fwnmi:
EXCEPTION_PROLOG_0(PACA_EXMC)
machine_check_pSeries_0:
EXCEPTION_PROLOG_1(PACA_EXMC, KVMTEST, 0x200)
- EXCEPTION_PROLOG_PSERIES_1(machine_check_common, EXC_STD)
+ /*
+ * The following is essentially EXCEPTION_PROLOG_PSERIES_1 with the
+ * difference that MSR_RI is not enabled, because PACA_EXMC is being
+ * used, so nested machine check corrupts it. machine_check_common
+ * enables MSR_RI.
+ */
+ ld r12,PACAKBASE(r13)
+ ld r10,PACAKMSR(r13)
+ xori r10,r10,MSR_RI
+ mfspr r11,SPRN_SRR0
+ LOAD_HANDLER(r12, machine_check_common)
+ mtspr SPRN_SRR0,r12
+ mfspr r12,SPRN_SRR1
+ mtspr SPRN_SRR1,r10
+ rfid
+ b . /* prevent speculative execution */
+
KVM_HANDLER_SKIP(PACA_EXMC, EXC_STD, 0x200)
KVM_HANDLER_SKIP(PACA_EXGEN, EXC_STD, 0x300)
KVM_HANDLER_SKIP(PACA_EXSLB, EXC_STD, 0x380)
@@ -992,6 +1008,9 @@ machine_check_common:
RECONCILE_IRQ_STATE(r10, r11)
ld r3,PACA_EXMC+EX_DAR(r13)
lwz r4,PACA_EXMC+EX_DSISR(r13)
+ /* Enable MSR_RI when finished with PACA_EXMC */
+ li r10,MSR_RI
+ mtmsrd r10,1
std r3,_DAR(r1)
std r4,_DSISR(r1)
bl save_nvgprs
--
2.8.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 1/2] powerpc/pseries: PACA save area fix for general exception vs MCE
2016-08-10 10:48 ` [PATCH 1/2] powerpc/pseries: PACA save area fix for general exception vs MCE Nicholas Piggin
@ 2016-08-11 6:45 ` Mahesh Jagannath Salgaonkar
0 siblings, 0 replies; 4+ messages in thread
From: Mahesh Jagannath Salgaonkar @ 2016-08-11 6:45 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev; +Cc: Shreyas B . Prabhu, Stewart Smith
On 08/10/2016 04:18 PM, Nicholas Piggin wrote:
> MCE must not use PACA_EXGEN. When a general exception enables MSR_RI,
> that means SPRN_SRR[01] and SPRN_SPRG are no longer used. However the
> PACA save area is still in use.
> ---
> arch/powerpc/kernel/exceptions-64s.S | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index 694def6..4174c4e 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -984,14 +984,14 @@ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_RADIX)
> machine_check_common:
>
> mfspr r10,SPRN_DAR
> - std r10,PACA_EXGEN+EX_DAR(r13)
> + std r10,PACA_EXMC+EX_DAR(r13)
> mfspr r10,SPRN_DSISR
> - stw r10,PACA_EXGEN+EX_DSISR(r13)
> + stw r10,PACA_EXMC+EX_DSISR(r13)
> EXCEPTION_PROLOG_COMMON(0x200, PACA_EXMC)
> FINISH_NAP
> RECONCILE_IRQ_STATE(r10, r11)
> - ld r3,PACA_EXGEN+EX_DAR(r13)
> - lwz r4,PACA_EXGEN+EX_DSISR(r13)
> + ld r3,PACA_EXMC+EX_DAR(r13)
> + lwz r4,PACA_EXMC+EX_DSISR(r13)
> std r3,_DAR(r1)
> std r4,_DSISR(r1)
> bl save_nvgprs
>
Yup agree. Looks like copy-paste was the culprit.
Acked-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-08-11 6:45 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2016-08-10 10:46 [RFC][PATCH 0/2] powerpc/pseries machine check reentrancy fixes Nicholas Piggin
2016-08-10 10:48 ` [PATCH 1/2] powerpc/pseries: PACA save area fix for general exception vs MCE Nicholas Piggin
2016-08-11 6:45 ` Mahesh Jagannath Salgaonkar
2016-08-10 10:48 ` [PATCH 2/2] powerpc/pseries: PACA save area fix for MCE " Nicholas Piggin
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