Messages in this thread Patch in this message | | | From | "Chang S. Bae" <> | Subject | [RFC PATCH v2 06/11] x86/cpu: Add a config option and a chicken bit for Key Locker | Date | Fri, 14 May 2021 13:15:03 -0700 |
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Add a kernel config option to enable the feature (disabled by default) at compile-time.
Also, add a new command-line parameter -- 'nokeylocker' to disable the feature at boot-time.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- Documentation/admin-guide/kernel-parameters.txt | 2 ++ arch/x86/Kconfig | 14 ++++++++++++++ arch/x86/kernel/cpu/common.c | 16 ++++++++++++++++ 3 files changed, 32 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index cb89dbdedc46..d0afe36c1802 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3284,6 +3284,8 @@ nohugevmalloc [PPC] Disable kernel huge vmalloc mappings. + nokeylocker [X86] Disables Key Locker hardware feature. + nosmt [KNL,S390] Disable symmetric multithreading (SMT). Equivalent to smt=1. diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 0045e1b44190..de8eeb705ed8 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1885,6 +1885,20 @@ config X86_INTEL_MEMORY_PROTECTION_KEYS If unsure, say y. +config X86_KEYLOCKER + prompt "Key Locker" + def_bool n + depends on CPU_SUP_INTEL + help + Key Locker is a new security feature to protect data encryption + keys for the Advanced Encryption Standard (AES) algorithm. + + When enabled, every CPU has a unique internal key to wrap AES + keys in an encoded format. The internal key is not accessible + to software once loaded. + + If unsure, say y. + choice prompt "TSX enable mode" depends on CPU_SUP_INTEL diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 2e64371acb81..c655cce30c2b 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -353,6 +353,22 @@ static __always_inline void setup_umip(struct cpuinfo_x86 *c) /* These bits should not change their value after CPU init is finished. */ static const unsigned long cr4_pinned_mask = X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP | X86_CR4_FSGSBASE; + +static __init int x86_nokeylocker_setup(char *arg) +{ + /* Expect an exact match without trailing characters. */ + if (strlen(arg)) + return 0; + + if (!cpu_feature_enabled(X86_FEATURE_KEYLOCKER)) + return 1; + + setup_clear_cpu_cap(X86_FEATURE_KEYLOCKER); + pr_info("x86/keylocker: Disabled by kernel command line.\n"); + return 1; +} +__setup("nokeylocker", x86_nokeylocker_setup); + static DEFINE_STATIC_KEY_FALSE_RO(cr_pinning); static unsigned long cr4_pinned_bits __ro_after_init; -- 2.17.1
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