Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 5e94c43..571e38c 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -428,28 +428,20 @@
 
 	lockdep_assert_irqs_disabled();
 
-	/*
-	 * If TIF_SSBD is different, select the proper mitigation
-	 * method. Note that if SSBD mitigation is disabled or permanentely
-	 * enabled this branch can't be taken because nothing can set
-	 * TIF_SSBD.
-	 */
-	if (tif_diff & _TIF_SSBD) {
-		if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) {
+	/* Handle change of TIF_SSBD depending on the mitigation method. */
+	if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) {
+		if (tif_diff & _TIF_SSBD)
 			amd_set_ssb_virt_state(tifn);
-		} else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) {
+	} else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) {
+		if (tif_diff & _TIF_SSBD)
 			amd_set_core_ssb_state(tifn);
-		} else if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
-			   static_cpu_has(X86_FEATURE_AMD_SSBD)) {
-			msr |= ssbd_tif_to_spec_ctrl(tifn);
-			updmsr  = true;
-		}
+	} else if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
+		   static_cpu_has(X86_FEATURE_AMD_SSBD)) {
+		updmsr |= !!(tif_diff & _TIF_SSBD);
+		msr |= ssbd_tif_to_spec_ctrl(tifn);
 	}
 
-	/*
-	 * Only evaluate TIF_SPEC_IB if conditional STIBP is enabled,
-	 * otherwise avoid the MSR write.
-	 */
+	/* Only evaluate TIF_SPEC_IB if conditional STIBP is enabled. */
 	if (IS_ENABLED(CONFIG_SMP) &&
 	    static_branch_unlikely(&switch_to_cond_stibp)) {
 		updmsr |= !!(tif_diff & _TIF_SPEC_IB);