This is a note to let you know that I've just added the patch titled
arm64: KVM: Add workaround for Cortex-A57 erratum 834220
to the 4.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-kvm-add-workaround-for-cortex-a57-erratum-834220.patch
and it can be found in the queue-4.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 498cd5c32be6e32bc0f8efcad48ab094bb2bfdf3 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@xxxxxxx>
Date: Mon, 16 Nov 2015 10:28:18 +0000
Subject: arm64: KVM: Add workaround for Cortex-A57 erratum 834220
From: Marc Zyngier <marc.zyngier@xxxxxxx>
commit 498cd5c32be6e32bc0f8efcad48ab094bb2bfdf3 upstream.
Cortex-A57 parts up to r1p2 can misreport Stage 2 translation faults
when a Stage 1 permission fault or device alignment fault should
have been reported.
This patch implements the workaround (which is to validate that the
Stage-1 translation actually succeeds) by using code patching.
Reviewed-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/Kconfig | 21 +++++++++++++++++++++
arch/arm64/include/asm/cpufeature.h | 3 ++-
arch/arm64/kernel/cpu_errata.c | 9 +++++++++
arch/arm64/kvm/hyp.S | 6 ++++++
4 files changed, 38 insertions(+), 1 deletion(-)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -311,6 +311,27 @@ config ARM64_ERRATUM_832075
If unsure, say Y.
+config ARM64_ERRATUM_834220
+ bool "Cortex-A57: 834220: Stage 2 translation fault might be incorrectly reported in presence of a Stage 1 fault"
+ depends on KVM
+ default y
+ help
+ This option adds an alternative code sequence to work around ARM
+ erratum 834220 on Cortex-A57 parts up to r1p2.
+
+ Affected Cortex-A57 parts might report a Stage 2 translation
+ fault as a the result of a Stage 1 fault for a load crossing
+ a page boundary when there is a Stage 1 permission or device
+ memory alignment fault and a Stage 2 translation fault
+
+ The workaround is to verify that the Stage-1 translation
+ doesn't generate a fault before handling the Stage-2 fault.
+ Please note that this does not necessarily enable the workaround,
+ as it depends on the alternative framework, which will only patch
+ the kernel if an affected CPU is detected.
+
+ If unsure, say Y.
+
config ARM64_ERRATUM_845719
bool "Cortex-A53: 845719: a load might read incorrect data"
depends on COMPAT
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -27,8 +27,9 @@
#define ARM64_HAS_SYSREG_GIC_CPUIF 3
#define ARM64_HAS_PAN 4
#define ARM64_HAS_LSE_ATOMICS 5
+#define ARM64_WORKAROUND_834220 6
-#define ARM64_NCAPS 6
+#define ARM64_NCAPS 7
#ifndef __ASSEMBLY__
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -74,6 +74,15 @@ const struct arm64_cpu_capabilities arm6
(1 << MIDR_VARIANT_SHIFT) | 2),
},
#endif
+#ifdef CONFIG_ARM64_ERRATUM_834220
+ {
+ /* Cortex-A57 r0p0 - r1p2 */
+ .desc = "ARM erratum 834220",
+ .capability = ARM64_WORKAROUND_834220,
+ MIDR_RANGE(MIDR_CORTEX_A57, 0x00,
+ (1 << MIDR_VARIANT_SHIFT) | 2),
+ },
+#endif
#ifdef CONFIG_ARM64_ERRATUM_845719
{
/* Cortex-A53 r0p[01234] */
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -1007,9 +1007,15 @@ el1_trap:
b.ne 1f // Not an abort we care about
/* This is an abort. Check for permission fault */
+alternative_if_not ARM64_WORKAROUND_834220
and x2, x1, #ESR_ELx_FSC_TYPE
cmp x2, #FSC_PERM
b.ne 1f // Not a permission fault
+alternative_else
+ nop // Force a Stage-1 translation to occur
+ nop // and return to the guest if it failed
+ nop
+alternative_endif
/*
* Check for Stage-1 page table walk, which is guaranteed
Patches currently in stable-queue which might be from marc.zyngier@xxxxxxx are
queue-4.3/arm-arm64-kvm-correct-pte-uncachedness-check.patch
queue-4.3/arm64-kvm-fix-aarch32-to-aarch64-register-mapping.patch
queue-4.3/arm64-cmpxchg_dbl-fix-return-value-type.patch
queue-4.3/arm64-kvm-add-workaround-for-cortex-a57-erratum-834220.patch
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