[PATCH v4 2/5] irqchip, gicv3: Workaround for Cavium ThunderX erratum 23154

David Daney
2015-08-17T17:00:53Z

On 08/14/2015 11:28 AM, Robert Richter wrote:
> From: Robert Richter <rrichter@cavium.com>
>
> This patch implements Cavium ThunderX erratum 23154.
>
> The gicv3 of ThunderX requires a modified version for reading the IAR
> status to ensure data synchronization. Since this is in the fast-path
> and called with each interrupt, runtime patching is used using jump
> label patching for smallest overhead (no-op). This is the same
> technique as used for tracepoints.
>
> v4:
> * simplify code to only use cpus_have_cap() in gicv3_enable_quirks()
>
> v3:
> * fix erratum to be dependend from midr
> * use arm64 errata framework
>
> v2:
> * implement code in a single asm() to keep instruction sequence
> * added comment to the code that explains the erratum
> * apply workaround also if running as guest, thus check MIDR
>
> Signed-off-by: Robert Richter <rrichter@cavium.com>
> ---
> arch/arm64/Kconfig | 11 ++++++++++
> arch/arm64/include/asm/cpufeature.h | 3 ++-
> arch/arm64/include/asm/cputype.h | 18 +++++++++-------
> arch/arm64/kernel/cpu_errata.c | 9 ++++++++
> drivers/irqchip/irq-gic-v3.c | 42 ++++++++++++++++++++++++++++++++++++-
> 5 files changed, 74 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 0f6edb14b7e4..4f866a4c6536 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -417,6 +417,17 @@ config ARM64_ERRATUM_845719
>
> If unsure, say Y.
>
> +config CAVIUM_ERRATUM_23154
> + bool "Cavium erratum 23154: Access to ICC_IAR1_EL1 is not sync'ed"
> + depends on ARCH_THUNDER

None of the other errata depend on a specific ARCH_*. I think we should
remove this 'depends on', so that a generic kernel can be configured to
work on Thunder without having to first select ARCH_THUNDER.

David Daney

> + default y
> + help
> + The gicv3 of ThunderX requires a modified version for
> + reading the IAR status to ensure data synchronization
> + (access to icc_iar1_el1 is not sync'ed before and after).
> +
> + If unsure, say Y.
> +
> endmenu
>
>
>