[tip: x86/bugs] x86/bugs: Use switch/case in its_apply_mitigation()

[tip-bot2 for Pawan Gupta]

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

Commit-ID:     7e44909e0ea8346ba08b244ecc275fc3394e2b8e
Gitweb:        https://git.kernel.org/tip/7e44909e0ea8346ba08b244ecc275fc3394e2b8e
Author:        Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
AuthorDate:    Wed, 11 Jun 2025 10:29:47 -07:00
Committer:     Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Mon, 23 Jun 2025 12:22:44 +02:00

x86/bugs: Use switch/case in its_apply_mitigation()

Prepare to apply stuffing mitigation in its_apply_mitigation(). This is
currently only done via retbleed mitigation. Also using switch/case
makes it evident that mitigation mode like VMEXIT_ONLY doesn't need any
special handling.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Nikolay Borisov <nik.borisov@xxxxxxxx>
Link: https://lore.kernel.org/20250611-eibrs-fix-v4-4-5ff86cac6c61@xxxxxxxxxxxxxxx
---
 arch/x86/kernel/cpu/bugs.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 20696ab..e861e88 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1468,15 +1468,21 @@ static void __init its_update_mitigation(void)
 
 static void __init its_apply_mitigation(void)
 {
+	switch (its_mitigation) {
+	case ITS_MITIGATION_OFF:
+	case ITS_MITIGATION_AUTO:
+	case ITS_MITIGATION_VMEXIT_ONLY:
 	/* its=stuff forces retbleed stuffing and is enabled there. */
-	if (its_mitigation != ITS_MITIGATION_ALIGNED_THUNKS)
-		return;
-
-	if (!boot_cpu_has(X86_FEATURE_RETPOLINE))
-		setup_force_cpu_cap(X86_FEATURE_INDIRECT_THUNK_ITS);
+	case ITS_MITIGATION_RETPOLINE_STUFF:
+		break;
+	case ITS_MITIGATION_ALIGNED_THUNKS:
+		if (!boot_cpu_has(X86_FEATURE_RETPOLINE))
+			setup_force_cpu_cap(X86_FEATURE_INDIRECT_THUNK_ITS);
 
-	setup_force_cpu_cap(X86_FEATURE_RETHUNK);
-	set_return_thunk(its_return_thunk);
+		setup_force_cpu_cap(X86_FEATURE_RETHUNK);
+		set_return_thunk(its_return_thunk);
+		break;
+	}
 }
 
 #undef pr_fmt