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| author | Liu Song <liusong@linux.alibaba.com> | 2025-06-07 15:25:18 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-27 11:04:23 +0100 |
| commit | d38941ee87aa1e5848515f14cd61fa0e057ba512 (patch) | |
| tree | 8622a9dcbd7fac6f319d39b3c0b4076512ca4b4a | |
| parent | 86ca67653d1a48ee41a9d4a7cd33dfd700dabd90 (diff) | |
| download | linux-d38941ee87aa1e5848515f14cd61fa0e057ba512.tar.gz linux-d38941ee87aa1e5848515f14cd61fa0e057ba512.tar.bz2 linux-d38941ee87aa1e5848515f14cd61fa0e057ba512.zip | |
arm64: spectre: increase parameters that can be used to turn off bhb mitigation individually
[ Upstream commit 877ace9eab7de032f954533afd5d1ecd0cf62eaf ]
In our environment, it was found that the mitigation BHB has a great
impact on the benchmark performance. For example, in the lmbench test,
the "process fork && exit" test performance drops by 20%.
So it is necessary to have the ability to turn off the mitigation
individually through cmdline, thus avoiding having to compile the
kernel by adjusting the config.
Signed-off-by: Liu Song <liusong@linux.alibaba.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/1661514050-22263-1-git-send-email-liusong@linux.alibaba.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | arch/arm64/kernel/proton-pack.c | 9 |
2 files changed, 13 insertions, 1 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 88110e74b3f7..1eff15169983 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2954,6 +2954,7 @@ spec_store_bypass_disable=off [X86,PPC] spectre_v2_user=off [X86] ssbd=force-off [ARM64] + nospectre_bhb [ARM64] tsx_async_abort=off [X86] Exceptions: @@ -3367,6 +3368,10 @@ vulnerability. System may allow data leaks with this option. + nospectre_bhb [ARM64] Disable all mitigations for Spectre-BHB (branch + history injection) vulnerability. System may allow data leaks + with this option. + nospec_store_bypass_disable [HW] Disable all mitigations for the Speculative Store Bypass vulnerability diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index 223527066a4f..7728026d98f7 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -1088,6 +1088,13 @@ static void kvm_setup_bhb_slot(const char *hyp_vecs_start) { } #endif /* CONFIG_KVM */ static bool spectre_bhb_fw_mitigated; +static bool __read_mostly __nospectre_bhb; +static int __init parse_spectre_bhb_param(char *str) +{ + __nospectre_bhb = true; + return 0; +} +early_param("nospectre_bhb", parse_spectre_bhb_param); void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *entry) { @@ -1100,7 +1107,7 @@ void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *entry) /* No point mitigating Spectre-BHB alone. */ } else if (!IS_ENABLED(CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY)) { pr_info_once("spectre-bhb mitigation disabled by compile time option\n"); - } else if (cpu_mitigations_off()) { + } else if (cpu_mitigations_off() || __nospectre_bhb) { pr_info_once("spectre-bhb mitigation disabled by command line option\n"); } else if (supports_ecbhb(SCOPE_LOCAL_CPU)) { state = SPECTRE_MITIGATED; |