[PATCH v12 05/12] x86/vmscape: Move mitigation selection to a switch()
From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Date: 2026-06-23 17:33:55
Also in:
bpf, kvm, linux-doc, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit), x86 hardware vulnerabilities · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Peter Zijlstra, Josh Poimboeuf
This ensures that all mitigation modes are explicitly handled, while keeping the mitigation selection for each mode together. This also prepares for adding BHB-clearing mitigation mode for VMSCAPE. Tested-by: Jon Kohler <redacted> Reviewed-by: Nikolay Borisov <redacted> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> --- arch/x86/kernel/cpu/bugs.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 002bf4adccc3..636280c612f0 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c@@ -3088,17 +3088,33 @@ early_param("vmscape", vmscape_parse_cmdline); static void __init vmscape_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_VMSCAPE) || - !boot_cpu_has(X86_FEATURE_IBPB)) { + if (!boot_cpu_has_bug(X86_BUG_VMSCAPE)) { vmscape_mitigation = VMSCAPE_MITIGATION_NONE; return; } - if (vmscape_mitigation == VMSCAPE_MITIGATION_AUTO) { - if (should_mitigate_vuln(X86_BUG_VMSCAPE)) + if ((vmscape_mitigation == VMSCAPE_MITIGATION_AUTO) && + !should_mitigate_vuln(X86_BUG_VMSCAPE)) + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + + switch (vmscape_mitigation) { + case VMSCAPE_MITIGATION_NONE: + break; + + case VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER: + if (!boot_cpu_has(X86_FEATURE_IBPB)) + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + break; + + case VMSCAPE_MITIGATION_AUTO: + if (boot_cpu_has(X86_FEATURE_IBPB)) vmscape_mitigation = VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER; else vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + break; + + default: + break; } }
--
2.34.1