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authorJosh Poimboeuf <jpoimboe@kernel.org>2024-04-10 22:40:50 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2024-04-17 11:18:29 +0200
commit7f18a0df76217683500979dcb0a2faa7f3eccfa5 (patch)
treeec02f686787435e89681861171b537ff6aed376e
parentd737d8cd8e64e34c429e1ac5d3502159aeed3446 (diff)
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x86/bugs: Remove CONFIG_BHI_MITIGATION_AUTO and spectre_bhi=auto
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/412e9dc87971b622bbbaf64740ebc1f140bff343.1712813475.git.jpoimboe@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--Documentation/admin-guide/hw-vuln/spectre.rst4
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt3
-rw-r--r--arch/x86/Kconfig4
-rw-r--r--arch/x86/kernel/cpu/bugs.c10
4 files changed, 1 insertions, 20 deletions
diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst
index 081f28900898..e0a1be97fa75 100644
--- 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
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index e93ecb388656..aebbe2981241 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5742,9 +5742,6 @@
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.
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ba815ac474a1..be5b3a48c8cd 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2581,10 +2581,6 @@ 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
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index d3e1f0614f09..0b0fea179b0d 100644
--- 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(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 :
- 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_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);
@@ -1650,9 +1645,6 @@ 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");