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arm64: KVM: Add workaround for Cortex-A57 erratum 834220

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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.

Cc: stable@vger.kernel.org
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Marc Zyngier 2015-11-16 10:28:18 +00:00 committed by Christoffer Dall
parent c0f0963464
commit 498cd5c32b
4 changed files with 38 additions and 1 deletions
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21
arch/arm64/Kconfig
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@ -316,6 +316,27 @@ 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 the result of a Stage 1 fault for load crossing a
page boundary when there is a permission or device memory
alignment fault at Stage 1 and a translation fault at Stage 2.
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

3
arch/arm64/include/asm/cpufeature.h
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@ -29,8 +29,9 @@
#define ARM64_HAS_PAN 4
#define ARM64_HAS_LSE_ATOMICS 5
#define ARM64_WORKAROUND_CAVIUM_23154 6
#define ARM64_WORKAROUND_834220 7
#define ARM64_NCAPS 7
#define ARM64_NCAPS 8
#ifndef __ASSEMBLY__

9
arch/arm64/kernel/cpu_errata.c
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@ -75,6 +75,15 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
(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] */

6
arch/arm64/kvm/hyp.S
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@ -1015,9 +1015,15 @@ 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 // Use the permission fault path to
nop // check for a valid S1 translation,
nop // regardless of the ESR value.
alternative_endif
/*
* Check for Stage-1 page table walk, which is guaranteed