x86/bugs: TSX not disabled at late loading

When the microcode feature for disabling TSX is not available at boot time,
taa_select_mitigation will not disable TSX to ensure proper mitigation for TAA.
Call tsx_init before selecting TAA mitigation.

Orabug: 30557078

Suggested-by: Jamie Iles <[email protected]>
Suggested-by: Boris Ostrovsky <[email protected]>
Signed-off-by: Mihai Carabas <[email protected]>
Reviewed-by: Boris Ostrovsky <[email protected]>
Signed-off-by: Somasundaram Krishnasamy <[email protected]>

Author: mcarabas

arch/x86/kernel/cpu/bugs.c

@@ -285,6 +285,14 @@ void __ref check_bugs(void)
 
 	/* Relies on the result of spectre_v2_select_mitigation. */
 	ssb_init();
+
+	/*
+	 * If we are at late loading, we need to re-initialize
+	 * tsx becasue tsx control might be available.
+	 */
+	if (system_state == SYSTEM_RUNNING)
+		tsx_init();
+
 	l1tf_select_mitigation();
 	mds_select_mitigation();
 	taa_select_mitigation();

arch/x86/kernel/cpu/cpu.h

@@ -52,9 +52,9 @@ enum tsx_ctrl_states {
 	TSX_CTRL_NOT_SUPPORTED,
 };
 
-extern __ro_after_init enum tsx_ctrl_states tsx_ctrl_state;
+extern enum tsx_ctrl_states tsx_ctrl_state;
 
-extern void __init tsx_init(void);
+extern void tsx_init(void);
 extern void tsx_enable(void);
 extern void tsx_disable(void);
 #else

arch/x86/kernel/cpu/tsx.c

@@ -14,7 +14,7 @@
 
 #include "cpu.h"
 
-enum tsx_ctrl_states tsx_ctrl_state __ro_after_init = TSX_CTRL_NOT_SUPPORTED;
+enum tsx_ctrl_states tsx_ctrl_state = TSX_CTRL_NOT_SUPPORTED;
 
 void tsx_disable(void)
 {
@@ -55,7 +55,7 @@ void tsx_enable(void)
 	wrmsrl(MSR_IA32_TSX_CTRL, tsx);
 }
 
-static bool __init tsx_ctrl_is_supported(void)
+static bool tsx_ctrl_is_supported(void)
 {
 	u64 ia32_cap = x86_read_arch_cap_msr();
 
@@ -81,15 +81,15 @@ static enum tsx_ctrl_states x86_get_tsx_auto_mode(void)
 	return TSX_CTRL_ENABLE;
 }
 
-void __init tsx_init(void)
+void tsx_init(void)
 {
 	char arg[5] = {};
 	int ret;
 
 	if (!tsx_ctrl_is_supported())
 		return;
 
-	ret = cmdline_find_option(boot_command_line, "tsx", arg, sizeof(arg));
+	ret = cmdline_find_option(saved_command_line, "tsx", arg, sizeof(arg));
 	if (ret >= 0) {
 		if (!strcmp(arg, "on")) {
 			tsx_ctrl_state = TSX_CTRL_ENABLE;