linux-kernel - [PATCH v5 19/20] x86/bugs: Print enabled attack vectors

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Message-ID: <20250509162839.3057217-20-david.kaplan@amd.com>
Date: Fri, 9 May 2025 11:28:38 -0500
From: David Kaplan <david.kaplan@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar
	<mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>
CC: <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 19/20] x86/bugs: Print enabled attack vectors

Print the status of enabled attack vectors and SMT mitigation status in the
boot log for easier reporting and debugging.  This information will also be
available through sysfs.

Signed-off-by: David Kaplan <david.kaplan@....com>
---
 arch/x86/kernel/cpu/bugs.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 55b0658562c0..4e01903ca6fd 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -177,6 +177,39 @@ DEFINE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush);
 DEFINE_STATIC_KEY_FALSE(cpu_buf_vm_clear);
 EXPORT_SYMBOL_GPL(cpu_buf_vm_clear);
 
+#undef pr_fmt
+#define pr_fmt(fmt)	"mitigations: " fmt
+
+static void __init cpu_print_attack_vectors(void)
+{
+	pr_info("Enabled attack vectors: ");
+
+	if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL))
+		pr_cont("user_kernel, ");
+
+	if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER))
+		pr_cont("user_user, ");
+
+	if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST))
+		pr_cont("guest_host, ");
+
+	if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_GUEST))
+		pr_cont("guest_guest, ");
+
+	pr_cont("SMT mitigations: ");
+
+	switch (smt_mitigations) {
+	case SMT_MITIGATIONS_OFF:
+		pr_cont("off\n");
+		break;
+	case SMT_MITIGATIONS_AUTO:
+		pr_cont("auto\n");
+		break;
+	case SMT_MITIGATIONS_ON:
+		pr_cont("on\n");
+	}
+}
+
 void __init cpu_select_mitigations(void)
 {
 	/*
@@ -197,6 +230,8 @@ void __init cpu_select_mitigations(void)
 
 	x86_arch_cap_msr = x86_read_arch_cap_msr();
 
+	cpu_print_attack_vectors();
+
 	/* Select the proper CPU mitigations before patching alternatives: */
 	spectre_v1_select_mitigation();
 	spectre_v2_select_mitigation();
-- 
2.34.1