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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2024-07-15 20:07:27 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2024-07-15 20:07:27 -0700 |
| commit | 2439a5eaa753d22759fb4248e0f5e459503fffad (patch) | |
| tree | 2622a88a4e99fcd9859ee0e0bd7af8ecf054df7a /arch/x86/kernel/cpu | |
| parent | f998678baf3c143fec4c66e7f3a84bae3b25ff12 (diff) | |
| parent | 42c141fbb651b64db492aab35bc1d96eb4c20261 (diff) | |
Merge tag 'x86_bugs_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu mitigation updates from Borislav Petkov:
- Add a spectre_bhi=vmexit mitigation option aimed at cloud
environments
- Remove duplicated Spectre cmdline option documentation
- Add separate macro definitions for syscall handlers which do not
return in order to address objtool warnings
* tag 'x86_bugs_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/bugs: Add 'spectre_bhi=vmexit' cmdline option
x86/bugs: Remove duplicate Spectre cmdline option descriptions
x86/syscall: Mark exit[_group] syscall handlers __noreturn
Diffstat (limited to 'arch/x86/kernel/cpu')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index b6f927f6c567..45675da354f3 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1625,6 +1625,7 @@ static bool __init spec_ctrl_bhi_dis(void) enum bhi_mitigations { BHI_MITIGATION_OFF, BHI_MITIGATION_ON, + BHI_MITIGATION_VMEXIT_ONLY, }; static enum bhi_mitigations bhi_mitigation __ro_after_init = @@ -1639,6 +1640,8 @@ 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, "vmexit")) + bhi_mitigation = BHI_MITIGATION_VMEXIT_ONLY; else pr_err("Ignoring unknown spectre_bhi option (%s)", str); @@ -1659,19 +1662,22 @@ static void __init bhi_select_mitigation(void) return; } + /* Mitigate in hardware if supported */ if (spec_ctrl_bhi_dis()) return; if (!IS_ENABLED(CONFIG_X86_64)) return; - /* Mitigate KVM by default */ - 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_VMEXIT_ONLY) { + pr_info("Spectre BHI mitigation: SW BHB clearing on VM exit only\n"); + setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT); + return; + } - /* Mitigate syscalls when the mitigation is forced =on */ + pr_info("Spectre BHI mitigation: SW BHB clearing on syscall and VM exit\n"); setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP); - pr_info("Spectre BHI mitigation: SW BHB clearing on syscall\n"); + setup_force_cpu_cap(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT); } static void __init spectre_v2_select_mitigation(void) |