From: Vladimir Murzin <vladimir.murzin@arm•com>
To: Zeng Heng <zengheng@huaweicloud•com>,
xuwei5@huawei•com, wangyushan12@huawei•com,
yangyicong@hisilicon•com, maz@kernel•org, yeoreum.yun@arm•com,
miko.lenczewski@arm•com, james.clark@linaro•org, corbet@lwn•net,
skhan@linuxfoundation•org, kuninori.morimoto.gx@renesas•com,
lucaswei@google•com, catalin.marinas@arm•com, broonie@kernel•org,
lpieralisi@kernel•org, thuth@redhat•com, kevin.brodsky@arm•com,
tongtiangen@huawei•com, oupton@kernel•org, ryan.roberts@arm•com,
mark.rutland@arm•com, will@kernel•org, Sascha.Bischoff@arm•com
Cc: linux-arm-kernel@lists•infradead.org, wangkefeng.wang@huawei•com,
linux-doc@vger•kernel.org, linux-kernel@vger•kernel.org
Subject: Re: [PATCH v3 1/2] arm64: cpufeature: Add WORKAROUND_DISABLE_CNP capability
Date: Tue, 2 Jun 2026 10:23:38 +0100 [thread overview]
Message-ID: <701c88b1-c172-4fee-ba56-18bbe940016f@arm.com> (raw)
In-Reply-To: <20260601112000.1145391-2-zengheng@huaweicloud.com>
On 6/1/26 12:19, Zeng Heng wrote:
> From: Zeng Heng <zengheng4@huawei•com>
>
> The NVIDIA Carmel CNP erratum is not the only case requiring CNP to be
> disabled. Abstract this into a common WORKAROUND_DISABLE_CNP capability
> to facilitate adding errata for future chips and reduce duplicate
> checks in has_useable_cnp().
>
> This serves as a prerequisite for the subsequent Hisilicon erratum
> 162100125.
>
> Suggested-by: Vladimir Murzin <vladimir.murzin@arm•com>
> Signed-off-by: Zeng Heng <zengheng4@huawei•com>
> ---
> arch/arm64/Kconfig | 4 ++++
> arch/arm64/include/asm/cpucaps.h | 4 ++--
> arch/arm64/kernel/cpu_errata.c | 4 ++--
> arch/arm64/kernel/cpufeature.c | 2 +-
> arch/arm64/tools/cpucaps | 2 +-
> 5 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index fe60738e5943..f297517a83b9 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1315,9 +1315,13 @@ config QCOM_FALKOR_ERRATUM_E1041
>
> If unsure, say Y.
>
> +config ARM64_WORKAROUND_DISABLE_CNP
> + bool
> +
> config NVIDIA_CARMEL_CNP_ERRATUM
> bool "NVIDIA Carmel CNP: CNP on Carmel semantically different than ARM cores"
> default y
> + select ARM64_WORKAROUND_DISABLE_CNP
> help
> If CNP is enabled on Carmel cores, non-sharable TLBIs on a core will not
> invalidate shared TLB entries installed by a different core, as it would
> diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
> index d0d3cdd5763c..25c61cda901c 100644
> --- a/arch/arm64/include/asm/cpucaps.h
> +++ b/arch/arm64/include/asm/cpucaps.h
> @@ -58,8 +58,8 @@ cpucap_is_possible(const unsigned int cap)
> return IS_ENABLED(CONFIG_ARM64_ERRATUM_2658417);
> case ARM64_WORKAROUND_CAVIUM_23154:
> return IS_ENABLED(CONFIG_CAVIUM_ERRATUM_23154);
> - case ARM64_WORKAROUND_NVIDIA_CARMEL_CNP:
> - return IS_ENABLED(CONFIG_NVIDIA_CARMEL_CNP_ERRATUM);
> + case ARM64_WORKAROUND_DISABLE_CNP:
> + return IS_ENABLED(CONFIG_ARM64_WORKAROUND_DISABLE_CNP);
> case ARM64_WORKAROUND_REPEAT_TLBI:
> return IS_ENABLED(CONFIG_ARM64_WORKAROUND_REPEAT_TLBI);
> case ARM64_WORKAROUND_SPECULATIVE_SSBS:
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index 5377e4c2eba2..b0db946568b7 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -801,11 +801,11 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
> 1, 0),
> },
> #endif
> -#ifdef CONFIG_NVIDIA_CARMEL_CNP_ERRATUM
> +#ifdef CONFIG_ARM64_WORKAROUND_DISABLE_CNP
> {
> /* NVIDIA Carmel */
> .desc = "NVIDIA Carmel CNP erratum",
> - .capability = ARM64_WORKAROUND_NVIDIA_CARMEL_CNP,
> + .capability = ARM64_WORKAROUND_DISABLE_CNP,
> ERRATA_MIDR_ALL_VERSIONS(MIDR_NVIDIA_CARMEL),
> },
> #endif
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 6d53bb15cf7b..20c5f24f74a9 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -1785,7 +1785,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
> if (is_kdump_kernel())
> return false;
>
> - if (cpus_have_cap(ARM64_WORKAROUND_NVIDIA_CARMEL_CNP))
> + if (cpus_have_cap(ARM64_WORKAROUND_DISABLE_CNP))
> return false;
>
> return has_cpuid_feature(entry, scope);
> diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps
> index 811c2479e82d..9b85a84f6fd4 100644
> --- a/arch/arm64/tools/cpucaps
> +++ b/arch/arm64/tools/cpucaps
> @@ -120,7 +120,7 @@ WORKAROUND_CAVIUM_TX2_219_PRFM
> WORKAROUND_CAVIUM_TX2_219_TVM
> WORKAROUND_CLEAN_CACHE
> WORKAROUND_DEVICE_LOAD_ACQUIRE
> -WORKAROUND_NVIDIA_CARMEL_CNP
> +WORKAROUND_DISABLE_CNP
> WORKAROUND_PMUV3_IMPDEF_TRAPS
> WORKAROUND_QCOM_FALKOR_E1003
> WORKAROUND_QCOM_ORYON_CNTVOFF
> --
> 2.43.0
>
FWIW,
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm•com>
next prev parent reply other threads:[~2026-06-02 9:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-01 11:19 [PATCH v3 0/2] arm64: cpufeature: Add WORKAROUND_DISABLE_CNP capability Zeng Heng
2026-06-01 11:19 ` [PATCH v3 1/2] " Zeng Heng
2026-06-02 9:23 ` Vladimir Murzin [this message]
2026-06-01 11:20 ` [PATCH v3 2/2] arm64: kernel: Disable CNP on HiSilicon HIP09 Zeng Heng
2026-06-02 9:24 ` Vladimir Murzin
2026-06-02 15:53 ` Will Deacon
2026-06-03 1:13 ` Zeng Heng
2026-06-02 9:28 ` [PATCH v3 0/2] arm64: cpufeature: Add WORKAROUND_DISABLE_CNP capability Vladimir Murzin
2026-06-02 11:54 ` Wei Xu
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