[tip: x86/bugs] x86/bugs: Print enabled attack vectors

["tip-bot2 for David Kaplan" <tip-bot2@linutronix.de>]

The following commit has been merged into the x86/bugs branch of tip:

Commit-ID:     a026dc61cffd98541e048f3c88d3280bcd105bd4
Gitweb:        https://git.kernel.org/tip/a026dc61cffd98541e048f3c88d3280bcd105bd4
Author:        David Kaplan <david.kaplan@amd.com>
AuthorDate:    Mon, 07 Jul 2025 13:33:15 -05:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Fri, 11 Jul 2025 17:56:41 +02:00

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@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250707183316.1349127-21-david.kaplan@amd.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 b9d0509..b74bf93 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -189,6 +189,39 @@ 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)
 {
 	/*
@@ -209,6 +242,8 @@ 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();