Re: [PATCH v3 2/2] arm64: kernel: Disable CNP on HiSilicon HIP09

[Vladimir Murzin <vladimir.murzin@arm.com>]

On 6/1/26 12:20, Zeng Heng wrote:
> From: Zeng Heng <zengheng4@huawei.com>
> 
> HiSilicon HIP09 implements TLB entry matching behavior that deviates
> from the ARM architecture specification when the CNP (Common not Private)
> bit is set in TTBRx_ELx.
> 
> When TTBRx.CNP=1, TLB entries may be incorrectly shared between CPU
> cores, leading to TLB conflicts and stale mappings. This affects
> coherency and can result in incorrect translations.
> 
> Add the hardware erratum workaround (Hisilicon erratum 162100125) to
> disable CNP on affected HIP09 cores.
> 
> Co-developed-by: Tong Tiangen <tongtiangen@huawei.com>
> Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
> Signed-off-by: Zeng Heng <zengheng4@huawei.com>
> ---
>  Documentation/arch/arm64/silicon-errata.rst |  2 ++
>  arch/arm64/Kconfig                          | 16 ++++++++++++++++
>  arch/arm64/kernel/cpu_errata.c              | 13 ++++++++++---
>  3 files changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst
> index 211119ce7adc..cd50059edb85 100644
> --- a/Documentation/arch/arm64/silicon-errata.rst
> +++ b/Documentation/arch/arm64/silicon-errata.rst
> @@ -284,6 +284,8 @@ stable kernels.
>  +----------------+-----------------+-----------------+-----------------------------+
>  | Hisilicon      | Hip09           | #162100801      | HISILICON_ERRATUM_162100801 |
>  +----------------+-----------------+-----------------+-----------------------------+
> +| Hisilicon      | Hip09           | #162100125      | HISILICON_ERRATUM_162100125 |
> ++----------------+-----------------+-----------------+-----------------------------+
>  +----------------+-----------------+-----------------+-----------------------------+
>  | Qualcomm Tech. | Kryo/Falkor v1  | E1003           | QCOM_FALKOR_ERRATUM_1003    |
>  +----------------+-----------------+-----------------+-----------------------------+
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index f297517a83b9..75638e37883d 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1273,6 +1273,22 @@ config HISILICON_ERRATUM_162100801
> 
>  	  If unsure, say Y.
> 
> +config HISILICON_ERRATUM_162100125
> +	bool "Hisilicon erratum 162100125"
> +	default y
> +	select ARM64_WORKAROUND_DISABLE_CNP
> +	help
> +	  On HiSilicon HIP09, TLB entry matching behavior when CNP
> +	  (TTBRx.CNP=1) is enabled differs from the ARM architecture
> +	  specification.
> +
> +	  TLB entries may be incorrectly shared between CPUs, potentially
> +	  causing TLB conflicts and stale mappings.
> +
> +	  Disable CNP support for affected HiSilicon HIP09 cores.
> +
> +	  If unsure, say Y.
> +
>  config QCOM_FALKOR_ERRATUM_1003
>  	bool "Falkor E1003: Incorrect translation due to ASID change"
>  	default y
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index b0db946568b7..02e0ee5c948c 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -608,6 +608,14 @@ static const struct midr_range erratum_ac04_cpu_23_list[] = {
>  };
>  #endif
> 
> +#ifdef CONFIG_ARM64_WORKAROUND_DISABLE_CNP
> +static const struct midr_range cnp_erratum_cpus[] = {
> +	MIDR_ALL_VERSIONS(MIDR_NVIDIA_CARMEL),
> +	MIDR_ALL_VERSIONS(MIDR_HISI_HIP09),
> +	{},
> +};
> +#endif
> +
>  const struct arm64_cpu_capabilities arm64_errata[] = {
>  #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE
>  	{
> @@ -803,10 +811,9 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
>  #endif
>  #ifdef CONFIG_ARM64_WORKAROUND_DISABLE_CNP
>  	{
> -		/* NVIDIA Carmel */
> -		.desc = "NVIDIA Carmel CNP erratum",
> +		.desc = "NVIDIA Carmel CNP erratum, or Hisilicon erratum 162100125",
>  		.capability = ARM64_WORKAROUND_DISABLE_CNP,
> -		ERRATA_MIDR_ALL_VERSIONS(MIDR_NVIDIA_CARMEL),
> +		ERRATA_MIDR_RANGE_LIST(cnp_erratum_cpus),
>  	},
>  #endif
>  #ifdef CONFIG_ARM64_WORKAROUND_TRBE_OVERWRITE_FILL_MODE
> --
> 2.43.0
> 

FWIW,

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>