From: Vladimir Murzin <vladimir.murzin@arm.com> hulk inclusion category: feature bugzilla: 29839 CVE: NA ------------------------------------------------- There are cases when activating of Common Not Private (CNP) feature might not be desirable; this patch allows to forcefully disable CNP even it is supported by hardware. Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> Reviewed-by: Hanjun Guo <guohanjun@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ arch/arm64/kernel/cpufeature.c | 11 ++++++++++- 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ac90826a2b915..514b884e8105b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2927,6 +2927,10 @@ noclflush [BUGS=X86] Don't use the CLFLUSH instruction + nocnp [ARM64] + Disable CNP (Common not Private translations) + even if it is supported by processor. + nodelayacct [KNL] Disable per-task delay accounting nodsp [SH] Disable hardware DSP at boot time. diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index d09658c27db83..f9bc3603e77ef 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1057,6 +1057,15 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, return !meltdown_safe; } +static bool nocnp; + +static int __init early_nocnp(char *p) +{ + nocnp = true; + return 0; +} +early_param("nocnp", early_nocnp); + static bool __maybe_unused has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope) { @@ -1068,7 +1077,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope) if (is_kdump_kernel()) return false; - return has_cpuid_feature(entry, scope); + return has_cpuid_feature(entry, scope) && !nocnp; } #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 -- 2.25.1