From: Nicholas Piggin <npiggin@gmail•com>
To: linuxppc-dev@ozlabs•org
Cc: Nicholas Piggin <npiggin@gmail•com>,
Mahesh Salgaonkar <mahesh@linux•vnet.ibm.com>,
"Shreyas B . Prabhu" <shreyas@linux•vnet.ibm.com>,
Stewart Smith <stewart@linux•vnet.ibm.com>
Subject: [PATCH 2/2] powerpc/pseries: PACA save area fix for MCE vs MCE
Date: Wed, 10 Aug 2016 20:48:43 +1000 [thread overview]
Message-ID: <1470826123-14699-3-git-send-email-npiggin@gmail.com> (raw)
In-Reply-To: <1470826005-14520-1-git-send-email-npiggin@gmail.com>
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
prev parent reply other threads:[~2016-08-10 10:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
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 ` Nicholas Piggin [this message]
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