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

Date: Thu, 19 May 2022 20:28:10 -0700

Subject: x86/speculation: Add a common function for MD_CLEAR mitigation update

Git-commit: f52ea6c26953fed339aa4eae717ee5c2133c7ff2

Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git

Patch-mainline: Queued in tip for v5.19

References: bsc#1199650 CVE-2022-21166 CVE-2022-21127 CVE-2022-21123 CVE-2022-21125 CVE-2022-21180

Processor MMIO Stale Data mitigation uses similar mitigation as MDS and

TAA. In preparation for adding its mitigation, add a common function to

update all mitigations that depend on MD_CLEAR.

  [ bp: Add a newline in md_clear_update_mitigation() to separate

    statements better. ]

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

Signed-off-by: Borislav Petkov <bp@suse.de>

---

 arch/x86/kernel/cpu/bugs.c |   59 +++++++++++++++++++++++++--------------------

 1 file changed, 33 insertions(+), 26 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c

+++ b/arch/x86/kernel/cpu/bugs.c

@@ -41,7 +41,7 @@ static void __init spectre_v2_select_mit

 static void __init ssb_select_mitigation(void);

 static void __init l1tf_select_mitigation(void);

 static void __init mds_select_mitigation(void);

-static void __init mds_print_mitigation(void);

+static void __init md_clear_update_mitigation(void);

 static void __init taa_select_mitigation(void);

 static void __init srbds_select_mitigation(void);

@@ -114,10 +114,10 @@ void __init check_bugs(void)

 	srbds_select_mitigation();

 	/*

-	 * As MDS and TAA mitigations are inter-related, print MDS

-	 * mitigation until after TAA mitigation selection is done.

+	 * As MDS and TAA mitigations are inter-related, update and print their

+	 * mitigation after TAA mitigation selection is done.

 	 */

-	mds_print_mitigation();

+	md_clear_update_mitigation();

 	arch_smt_update();

@@ -258,14 +258,6 @@ static void __init mds_select_mitigation

 	}

 }

-static void __init mds_print_mitigation(void)

-{

-	if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off())

-		return;

-

-	pr_info("%s\n", mds_strings[mds_mitigation]);

-}

-

 static int __init mds_cmdline(char *str)

 {

 	if (!boot_cpu_has_bug(X86_BUG_MDS))

@@ -313,7 +305,7 @@ static void __init taa_select_mitigation

 	/* TSX previously disabled by tsx=off */

 	if (!boot_cpu_has(X86_FEATURE_RTM)) {

 		taa_mitigation = TAA_MITIGATION_TSX_DISABLED;

-		goto out;

+		return;

 	}

 	if (cpu_mitigations_off()) {

@@ -327,7 +319,7 @@ static void __init taa_select_mitigation

 	 */

 	if (taa_mitigation == TAA_MITIGATION_OFF &&

 	    mds_mitigation == MDS_MITIGATION_OFF)

-		goto out;

+		return;

 	if (boot_cpu_has(X86_FEATURE_MD_CLEAR))

 		taa_mitigation = TAA_MITIGATION_VERW;

@@ -359,18 +351,6 @@ static void __init taa_select_mitigation

 	if (taa_nosmt || cpu_mitigations_auto_nosmt())

 		cpu_smt_disable(false);

-

-	/*

-	 * Update MDS mitigation, if necessary, as the mds_user_clear is

-	 * now enabled for TAA mitigation.

-	 */

-	if (mds_mitigation == MDS_MITIGATION_OFF &&

-	    boot_cpu_has_bug(X86_BUG_MDS)) {

-		mds_mitigation = MDS_MITIGATION_FULL;

-		mds_select_mitigation();

-	}

-out:

-	pr_info("%s\n", taa_strings[taa_mitigation]);

 }

 static int __init tsx_async_abort_parse_cmdline(char *str)

@@ -395,6 +375,33 @@ static int __init tsx_async_abort_parse_

 early_param("tsx_async_abort", tsx_async_abort_parse_cmdline);

 #undef pr_fmt

+#define pr_fmt(fmt)     "" fmt

+

+static void __init md_clear_update_mitigation(void)

+{

+	if (cpu_mitigations_off())

+		return;

+

+	if (!static_key_enabled(&mds_user_clear))

+		goto out;

+

+	/*

+	 * mds_user_clear is now enabled. Update MDS mitigation, if

+	 * necessary.

+	 */

+	if (mds_mitigation == MDS_MITIGATION_OFF &&

+	    boot_cpu_has_bug(X86_BUG_MDS)) {

+		mds_mitigation = MDS_MITIGATION_FULL;

+		mds_select_mitigation();

+	}

+out:

+	if (boot_cpu_has_bug(X86_BUG_MDS))

+		pr_info("MDS: %s\n", mds_strings[mds_mitigation]);

+	if (boot_cpu_has_bug(X86_BUG_TAA))

+		pr_info("TAA: %s\n", taa_strings[taa_mitigation]);

+}

+

+#undef pr_fmt

 #define pr_fmt(fmt)	"SRBDS: " fmt

 enum srbds_mitigations {