linux-kernel - Re: [PATCH] arm64: Add workaround for Cavium erratum 26026

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Message-ID: <57A3B660.4040309@gmail.com>
Date:	Thu, 04 Aug 2016 14:40:48 -0700
From:	David Daney <ddaney.cavm@...il.com>
To:	Robert Richter <robert.richter@...ium.com>
CC:	marc.zyngier@....com, linux@...linux.org.uk,
	catalin.marinas@....com, will.deacon@....com, mark.rutland@....com,
	Matthias Brugger <mbrugger@...e.com>, kvm@...r.kernel.org,
	suzuki.poulose@....com, zlim.lnx@...il.com, rkrcmar@...hat.com,
	david.daney@...ium.com, agraf@...e.de,
	linux-kernel@...r.kernel.org, ard.biesheuvel@...aro.org,
	lorenzo.pieralisi@....com, james.morse@....com,
	dave.long@...aro.org, pbonzini@...hat.com,
	kvmarm@...ts.cs.columbia.edu, christoffer.dall@...aro.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] arm64: Add workaround for Cavium erratum 26026

On 08/04/2016 01:57 PM, Robert Richter wrote:
> The patch below is on top of Matthias' patch series:
>
>   arm64: Implement IPI based TLB invalidation
>
> The series is used to enable a workaround for Cavium ThunderX pass 1.x
> systems.


Where are the rest of the patches in the series?  I would have expected 
something like "[PATCH 1/X] arm64:..." with X being greater than one.

>
> -Robert
>
>
>
>  From abb99ee83473d9ecffb4fdaae9c69435ca670bc8 Mon Sep 17 00:00:00 2001
> From: Robert Richter <rrichter@...ium.com>
> Date: Fri, 29 Jul 2016 09:40:04 +0200
> Subject: [PATCH] arm64: Add workaround for Cavium erratum 26026
>
> STX may return a wrong status value if the store was successful.
>
> This may happen on ThunderX T88 pass 1.x cpus if a broadcast TLBI is
> executed on another cpu in parallel to an STX. As a result atomic or
> non-blocking implementations can behave incorrectly. Use IPIs that
> call local TLBIs on other cpus to avoid this.
>
> Applies to ThunderX T88 pass 1.x cpus.
>
> Signed-off-by: Robert Richter <rrichter@...ium.com>
> ---
>   Documentation/arm64/silicon-errata.txt |  1 +
>   arch/arm64/Kconfig                     | 14 ++++++++++++++
>   arch/arm64/kernel/cpu_errata.c         |  8 ++++++++
>   3 files changed, 23 insertions(+)
>
> diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
> index 4da60b463995..0d870d934528 100644
> --- a/Documentation/arm64/silicon-errata.txt
> +++ b/Documentation/arm64/silicon-errata.txt
> @@ -58,5 +58,6 @@ stable kernels.
>   | Cavium         | ThunderX ITS    | #22375, #24313  | CAVIUM_ERRATUM_22375    |
>   | Cavium         | ThunderX ITS    | #23144          | CAVIUM_ERRATUM_23144    |
>   | Cavium         | ThunderX GICv3  | #23154          | CAVIUM_ERRATUM_23154    |
> +| Cavium         | ThunderX Core   | #26026          | CAVIUM_ERRATUM_26026    |
>   | Cavium         | ThunderX Core   | #27456          | CAVIUM_ERRATUM_27456    |
>   | Cavium         | ThunderX SMMUv2 | #27704          | N/A		       |
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 5a0a691d4220..8cbd9043ec6f 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -457,6 +457,20 @@ config CAVIUM_ERRATUM_23154
>
>   	  If unsure, say Y.
>
> +config CAVIUM_ERRATUM_26026
> +	bool "Cavium erratum 26026: STX may return wrong status value"
> +	default y
> +	help
> +	  STX may return a wrong status value if the store was
> +	  successful. This may happen on ThunderX T88 pass 1.x cpus if
> +	  a broadcast TLBI is executed on another cpu in parallel to
> +	  an STX. As a result atomic or non-blocking implementations
> +	  can behave incorrectly. Use IPIs that call local TLBIs on
> +	  other cpus to avoid this.
> +	  Applies to ThunderX T88 pass 1.x cpus.
> +
> +	  If unsure, say Y.
> +
>   config CAVIUM_ERRATUM_27456
>   	bool "Cavium erratum 27456: Broadcast TLBI instructions may cause icache corruption"
>   	default y
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index af716b65110d..1e1753a6408e 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -90,6 +90,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
>   		MIDR_RANGE(MIDR_THUNDERX, 0x00, 0x01),
>   	},
>   #endif
> +#ifdef CONFIG_CAVIUM_ERRATUM_26026
> +	{
> +	/* Cavium ThunderX, pass 1.x */
> +		.desc = "Cavium erratum 26026",
> +		.capability = ARM64_HAS_NO_BCAST_TLBI,
> +		MIDR_RANGE(MIDR_THUNDERX, 0x00, 0x01),
> +	},
> +#endif
>   #ifdef CONFIG_CAVIUM_ERRATUM_27456
>   	{
>   	/* Cavium ThunderX, T88 pass 1.x - 2.1 */
>