[PATCH] arm64: Work around Falkor erratum 1009

On 08/12/16 11:20, Will Deacon wrote:

On Wed, Dec 07, 2016 at 03:04:31PM -0500, Christopher Covington wrote:

quoted

From: Shanker Donthineni <redacted>

During a TLB invalidate sequence targeting the inner shareable
domain, Falkor may prematurely complete the DSB before all loads
and stores using the old translation are observed; instruction
fetches are not subject to the conditions of this erratum.

Signed-off-by: Shanker Donthineni <redacted>
Signed-off-by: Christopher Covington <redacted>
---
 arch/arm64/Kconfig                | 10 +++++++++
 arch/arm64/include/asm/cpucaps.h  |  3 ++-
 arch/arm64/include/asm/tlbflush.h | 43 +++++++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/cpu_errata.c    |  7 +++++++
 arch/arm64/kvm/hyp/tlb.c          | 39 ++++++++++++++++++++++++++++++-----
 5 files changed, 96 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1004a3d..125440f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -485,6 +485,16 @@ config QCOM_FALKOR_ERRATUM_E1003
 
 	  If unsure, say Y.
 
+config QCOM_FALKOR_ERRATUM_E1009
+	bool "Falkor E1009: Prematurely complete a DSB after a TLBI"
+	default y
+	help
+	  Falkor CPU may prematurely complete a DSB following a TLBI xxIS
+	  invalidate maintenance operations. Repeat the TLBI operation one
+	  more time to fix the issue.
+
+	  If unsure, say Y.

Call me perverse, but I like this workaround. People often tend to screw
up TLBI and DVM sync, but the IPI-based workaround is horribly invasive
and fragile. Simply repeating the operation tends to be enough to make
the chance of failure small enough to be acceptable.

quoted

diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index cb6a8c2..5357d7f 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h

@@ -35,7 +35,8 @@
 #define ARM64_HYP_OFFSET_LOW			14
 #define ARM64_MISMATCHED_CACHE_LINE_SIZE	15
 #define ARM64_WORKAROUND_QCOM_FALKOR_E1003	16
+#define ARM64_WORKAROUND_QCOM_FALKOR_E1009	17

Could you rename this to something like ARM64_WORKAROUND_REPEAT_TLBI, so
that it could potentially be used by others?

And add a parameter to it so that we can generate multiple TLBIs,
depending on the level of brokenness? ;-)

	M.
-- 
Jazz is not dead. It just smells funny...