5.15-stable review patch. If anyone has any objections, please let me know.
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From: Josh Poimboeuf jpoimboe@kernel.org
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@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Nikolay Borisov nik.borisov@suse.com Cc: Sean Christopherson seanjc@google.com Cc: Linus Torvalds torvalds@linux-foundation.org Link: https://lore.kernel.org/r/412e9dc87971b622bbbaf64740ebc1f140bff343.171281347... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -719,10 +719,6 @@ For user space mitigation: 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 @@ -5413,9 +5413,6 @@ 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 @@ -2523,10 +2523,6 @@ 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 @@ -1602,13 +1602,10 @@ 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) { @@ -1619,8 +1616,6 @@ 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);
@@ -1650,9 +1645,6 @@ 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");