6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> commit 36d4fe147c870f6d3f6602befd7ef44393a1c87a upstream. Unlike most other mitigations' "auto" options, spectre_bhi=auto only mitigates newer systems, which is confusing and not particularly useful. Remove it. Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx> Cc: Sean Christopherson <seanjc@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/412e9dc87971b622bbbaf64740ebc1f140bff343.1712813475.git.jpoimboe@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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, 1 insertion(+), 20 deletions(-) --- a/Documentation/admin-guide/hw-vuln/spectre.rst +++ b/Documentation/admin-guide/hw-vuln/spectre.rst @@ -669,10 +669,6 @@ 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 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5929,9 +5929,6 @@ 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. --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2584,10 +2584,6 @@ 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 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1624,13 +1624,10 @@ static bool __init spec_ctrl_bhi_dis(voi 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 : - IS_ENABLED(CONFIG_SPECTRE_BHI_OFF) ? BHI_MITIGATION_OFF : - BHI_MITIGATION_AUTO; + IS_ENABLED(CONFIG_SPECTRE_BHI_ON) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF; static int __init spectre_bhi_parse_cmdline(char *str) { @@ -1641,8 +1638,6 @@ static int __init spectre_bhi_parse_cmdl 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); @@ -1672,9 +1667,6 @@ static void __init bhi_select_mitigation 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");
