[SRU][P][PATCH 6/8] x86/bugs: Move cpu_bugs_smt_update() down

[Massimiliano Pellizzer]

From: Pawan Gupta <pawan.kumar.gupta at linux.intel.com>

BugLink: https://bugs.launchpad.net/bugs/2124105

Commit 6449f5baf9c78a7a442d64f4a61378a21c5db113 upstream.

cpu_bugs_smt_update() uses global variables from different mitigations. For
SMT updates it can't currently use vmscape_mitigation that is defined after
it.

Since cpu_bugs_smt_update() depends on many other mitigations, move it
after all mitigations are defined. With that, it can use vmscape_mitigation
in a moment.

No functional change.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta at linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen at linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen at linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp at alien8.de>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 28504e31029b1612a1cbf2b81db244124cad0bad linux-6.12.y)
CVE-2025-40300
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 arch/x86/kernel/cpu/bugs.c | 148 ++++++++++++++++++-------------------
 1 file changed, 74 insertions(+), 74 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index f27fb7dfbf97a..c88744c18b670 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2203,80 +2203,6 @@ static void __init tsa_select_mitigation(void)
 	pr_info("%s\n", tsa_strings[tsa_mitigation]);
 }
 
-void cpu_bugs_smt_update(void)
-{
-	mutex_lock(&spec_ctrl_mutex);
-
-	if (sched_smt_active() && unprivileged_ebpf_enabled() &&
-	    spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
-		pr_warn_once(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG);
-
-	switch (spectre_v2_user_stibp) {
-	case SPECTRE_V2_USER_NONE:
-		break;
-	case SPECTRE_V2_USER_STRICT:
-	case SPECTRE_V2_USER_STRICT_PREFERRED:
-		update_stibp_strict();
-		break;
-	case SPECTRE_V2_USER_PRCTL:
-	case SPECTRE_V2_USER_SECCOMP:
-		update_indir_branch_cond();
-		break;
-	}
-
-	switch (mds_mitigation) {
-	case MDS_MITIGATION_FULL:
-	case MDS_MITIGATION_VMWERV:
-		if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY))
-			pr_warn_once(MDS_MSG_SMT);
-		update_mds_branch_idle();
-		break;
-	case MDS_MITIGATION_OFF:
-		break;
-	}
-
-	switch (taa_mitigation) {
-	case TAA_MITIGATION_VERW:
-	case TAA_MITIGATION_UCODE_NEEDED:
-		if (sched_smt_active())
-			pr_warn_once(TAA_MSG_SMT);
-		break;
-	case TAA_MITIGATION_TSX_DISABLED:
-	case TAA_MITIGATION_OFF:
-		break;
-	}
-
-	switch (mmio_mitigation) {
-	case MMIO_MITIGATION_VERW:
-	case MMIO_MITIGATION_UCODE_NEEDED:
-		if (sched_smt_active())
-			pr_warn_once(MMIO_MSG_SMT);
-		break;
-	case MMIO_MITIGATION_OFF:
-		break;
-	}
-
-	switch (tsa_mitigation) {
-	case TSA_MITIGATION_USER_KERNEL:
-	case TSA_MITIGATION_VM:
-	case TSA_MITIGATION_FULL:
-	case TSA_MITIGATION_UCODE_NEEDED:
-		/*
-		 * TSA-SQ can potentially lead to info leakage between
-		 * SMT threads.
-		 */
-		if (sched_smt_active())
-			static_branch_enable(&cpu_buf_idle_clear);
-		else
-			static_branch_disable(&cpu_buf_idle_clear);
-		break;
-	case TSA_MITIGATION_NONE:
-		break;
-	}
-
-	mutex_unlock(&spec_ctrl_mutex);
-}
-
 #undef pr_fmt
 #define pr_fmt(fmt)	"Speculative Store Bypass: " fmt
 
@@ -3030,6 +2956,80 @@ static void __init vmscape_select_mitigation(void)
 #undef pr_fmt
 #define pr_fmt(fmt) fmt
 
+void cpu_bugs_smt_update(void)
+{
+	mutex_lock(&spec_ctrl_mutex);
+
+	if (sched_smt_active() && unprivileged_ebpf_enabled() &&
+	    spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE)
+		pr_warn_once(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG);
+
+	switch (spectre_v2_user_stibp) {
+	case SPECTRE_V2_USER_NONE:
+		break;
+	case SPECTRE_V2_USER_STRICT:
+	case SPECTRE_V2_USER_STRICT_PREFERRED:
+		update_stibp_strict();
+		break;
+	case SPECTRE_V2_USER_PRCTL:
+	case SPECTRE_V2_USER_SECCOMP:
+		update_indir_branch_cond();
+		break;
+	}
+
+	switch (mds_mitigation) {
+	case MDS_MITIGATION_FULL:
+	case MDS_MITIGATION_VMWERV:
+		if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY))
+			pr_warn_once(MDS_MSG_SMT);
+		update_mds_branch_idle();
+		break;
+	case MDS_MITIGATION_OFF:
+		break;
+	}
+
+	switch (taa_mitigation) {
+	case TAA_MITIGATION_VERW:
+	case TAA_MITIGATION_UCODE_NEEDED:
+		if (sched_smt_active())
+			pr_warn_once(TAA_MSG_SMT);
+		break;
+	case TAA_MITIGATION_TSX_DISABLED:
+	case TAA_MITIGATION_OFF:
+		break;
+	}
+
+	switch (mmio_mitigation) {
+	case MMIO_MITIGATION_VERW:
+	case MMIO_MITIGATION_UCODE_NEEDED:
+		if (sched_smt_active())
+			pr_warn_once(MMIO_MSG_SMT);
+		break;
+	case MMIO_MITIGATION_OFF:
+		break;
+	}
+
+	switch (tsa_mitigation) {
+	case TSA_MITIGATION_USER_KERNEL:
+	case TSA_MITIGATION_VM:
+	case TSA_MITIGATION_FULL:
+	case TSA_MITIGATION_UCODE_NEEDED:
+		/*
+		 * TSA-SQ can potentially lead to info leakage between
+		 * SMT threads.
+		 */
+		if (sched_smt_active())
+			static_branch_enable(&cpu_buf_idle_clear);
+		else
+			static_branch_disable(&cpu_buf_idle_clear);
+		break;
+	case TSA_MITIGATION_NONE:
+		break;
+	}
+
+	mutex_unlock(&spec_ctrl_mutex);
+}
+
 #ifdef CONFIG_SYSFS
 
 #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion"
-- 
2.48.1