hulk inclusion category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/I9O7V8

---------------------------

This reverts commit 1ef2a4268dee6b0cc9156de58b0978228f03f3d8.

Revert syscall performance degradation pre-patch.

Signed-off-by: liwei liwei728@huawei.com --- Documentation/admin-guide/hw-vuln/spectre.rst | 4 ++++ Documentation/admin-guide/kernel-parameters.txt | 3 +++ arch/x86/Kconfig | 4 ++++ arch/x86/kernel/cpu/bugs.c | 10 +++++++++- 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst index e0a1be97fa75..081f28900898 100644 --- a/Documentation/admin-guide/hw-vuln/spectre.rst +++ b/Documentation/admin-guide/hw-vuln/spectre.rst @@ -669,6 +669,10 @@ kernel command line. needed. off Disable the mitigation. + auto + Enable the HW mitigation if needed, but + *don't* enable the SW mitigation except for KVM. + The system may be vulnerable.

For spectre_v2_user see Documentation/admin-guide/kernel-parameters.txt

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 1fd094bec52a..f0ac624c73bb 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6054,6 +6054,9 @@ on - (default) Enable the HW or SW mitigation as needed. off - Disable the mitigation. + auto - Enable the HW mitigation if needed, but + *don't* enable the SW mitigation except + for KVM. The system may be vulnerable.

spectre_v2= [X86] Control mitigation of Spectre variant 2 (indirect branch speculation) vulnerability. diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d7562807f538..3f0c286ac662 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2651,6 +2651,10 @@ config SPECTRE_BHI_OFF bool "off" help Equivalent to setting spectre_bhi=off command line parameter. +config SPECTRE_BHI_AUTO + bool "auto" + help + Equivalent to setting spectre_bhi=auto command line parameter.

endchoice

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 4c5e33b0130b..c3cb6e88ee4e 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1624,10 +1624,13 @@ static bool __init spec_ctrl_bhi_dis(void) enum bhi_mitigations { BHI_MITIGATION_OFF, BHI_MITIGATION_ON, + BHI_MITIGATION_AUTO, };

static enum bhi_mitigations bhi_mitigation __ro_after_init = - IS_ENABLED(CONFIG_SPECTRE_BHI_ON) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF; + IS_ENABLED(CONFIG_SPECTRE_BHI_ON) ? BHI_MITIGATION_ON : + IS_ENABLED(CONFIG_SPECTRE_BHI_OFF) ? BHI_MITIGATION_OFF : + BHI_MITIGATION_AUTO;

static int __init spectre_bhi_parse_cmdline(char *str) { @@ -1638,6 +1641,8 @@ static int __init spectre_bhi_parse_cmdline(char *str) bhi_mitigation = BHI_MITIGATION_OFF; else if (!strcmp(str, "on")) bhi_mitigation = BHI_MITIGATION_ON; + else if (!strcmp(str, "auto")) + bhi_mitigation = BHI_MITIGATION_AUTO; else pr_err("Ignoring unknown spectre_bhi option (%s)", str);

@@ -1668,6 +1673,9 @@ static void __init bhi_select_mitigation(void) setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT); pr_info("Spectre BHI mitigation: SW BHB clearing on vm exit\n");

+ if (bhi_mitigation == BHI_MITIGATION_AUTO) + return; + /* Mitigate syscalls when the mitigation is forced =on */ setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP); pr_info("Spectre BHI mitigation: SW BHB clearing on syscall\n");