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[PATCH 4.3 157/157] arm64: KVM: Add workaround for Cortex-A57 erratum 834220

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.3 157/157] arm64: KVM: Add workaround for Cortex-A57 erratum 834220
Date 2016-01-27 21:30 +0100
Message-ID <qVET0-FR-9@gated-at.bofh.it> (permalink)
References <qVCRc-7CM-17@gated-at.bofh.it>
Organization linux.* mail to news gateway

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4.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

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@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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

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Thread

[PATCH 4.3 000/157] 4.3.5-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:10 +0100
  [PATCH 4.3 001/157] x86 smpboot: Re-enable init_udelay=0 by default on modern CPUs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:10 +0100
    Re: [PATCH 4.3 001/157] x86 smpboot: Re-enable init_udelay=0 by  default on modern CPUs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 23:30 +0100
    Re: [PATCH 4.3 001/157] x86 smpboot: Re-enable init_udelay=0 by  default on modern CPUs Donald Parsons <dparsons@brightdsl.net> - 2016-01-27 23:30 +0100
  [PATCH 4.3 052/157] ALSA: seq: Fix race at timer setup and close Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:10 +0100
  [PATCH 4.3 046/157] ALSA: hda - Add mic mute hotkey quirk for Lenovo ThinkCentre AIO Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:10 +0100
  [PATCH 4.3 010/157] KVM: svm: unconditionally intercept #DB Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:10 +0100
  [PATCH 4.3 155/157] mn10300: Select CONFIG_HAVE_UID16 to fix build failure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:10 +0100
  [PATCH 4.3 154/157] fix the regression from "direct-io: Fix negative return from dio read beyond eof" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:20 +0100
  [PATCH 4.3 126/157] powerpc/opal-irqchip: Fix deadlock introduced by "Fix double endian conversion" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:20 +0100
  [PATCH 4.3 135/157] arm64: cmpxchg_dbl: fix return value type Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:20 +0100
  [PATCH 4.3 134/157] arm64: bpf: fix mod-by-zero case Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:20 +0100
  [PATCH 4.3 044/157] ALSA: hda - Set SKL+ hda controller power at freeze() and thaw() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 128/157] powerpc: Make value-returning atomics fully ordered Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 157/157] arm64: KVM: Add workaround for Cortex-A57 erratum 834220 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 131/157] powerpc/module: Handle R_PPC64_ENTRY relocations Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 129/157] powerpc: Make {cmp}xchg* and their atomic_ versions fully ordered Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 133/157] arm64: bpf: fix div-by-zero case Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 156/157] arm64: restore bogomips information in /proc/cpuinfo Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 147/157] parisc iommu: fix panic due to trying to allocate too large region Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 132/157] recordmcount: arm64: Replace the ignored mcount call into nop Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 148/157] HID: wacom: Tie cached HID_DG_CONTACTCOUNT indices to report ID Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 150/157] HID: core: Avoid uninitialized buffer access Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 149/157] HID: wacom: Expect touch_max touches if HID_DG_CONTACTCOUNT not present Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 130/157] scripts/recordmcount.pl: support data in text section on powerpc Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  [PATCH 4.3 153/157] direct-io: Fix negative return from dio read beyond eof Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:30 +0100
  Re: [PATCH 4.3 000/157] 4.3.5-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-01-28 00:30 +0100
  Re: [PATCH 4.3 000/157] 4.3.5-stable review Guenter Roeck <linux@roeck-us.net> - 2016-01-28 03:20 +0100

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