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

commit f52ea6c26953fed339aa4eae717ee5c2133c7ff2 upstream

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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
CVE-2022-21166
CVE-2022-21123
CVE-2022-21125
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index ef53c7bc723c3cda1fb943b3998dd4efb7471c56..e61910d0a946740cc4f7e7f9aba168f799f43ccd 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -41,7 +41,7 @@ static void __init spectre_v2_select_mitigation(void);
 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);
 static void __init l1d_flush_select_mitigation(void);
@@ -123,10 +123,10 @@ void __init check_bugs(void)
        l1d_flush_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();
 
@@ -267,14 +267,6 @@ static void __init mds_select_mitigation(void)
        }
 }
 
-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))
@@ -329,7 +321,7 @@ static void __init taa_select_mitigation(void)
        /* 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()) {
@@ -343,7 +335,7 @@ static void __init taa_select_mitigation(void)
         */
        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;
@@ -375,18 +367,6 @@ static void __init taa_select_mitigation(void)
 
        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)
@@ -410,6 +390,33 @@ static int __init tsx_async_abort_parse_cmdline(char *str)
 }
 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