[PATCH 5.15 03/11] x86/speculation: Add a common function for MD_CLEAR mitigation update

Greg Kroah-Hartman
2022-06-14T18:50:01Z

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

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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);
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
}
}

-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
/* 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
*/
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

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)
@@ -411,6 +391,33 @@ 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 {