4 messages, 2 authors, 2016-08-11 · open the first message on its own page
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2016-08-10 10:47:04
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
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2016-08-10 10:49:07
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
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2016-08-10 10:49:33
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
From: Mahesh Jagannath Salgaonkar <hidden>
Date: 2016-08-11 06:45:25
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 <redacted>