diff mbox series

[v4] powerpc/64s: support nospectre_v2 cmdline option

Message ID 20190517131400.20503-1-cmr@informatik.wtf (mailing list archive)
State Superseded
Headers show
Series [v4] powerpc/64s: support nospectre_v2 cmdline option | expand

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Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch next (8150a153c013aa2dd1ffae43370b89ac1347a7fb)
snowpatch_ozlabs/build-ppc64le fail build failed!
snowpatch_ozlabs/build-ppc64be fail build failed!
snowpatch_ozlabs/build-ppc64e success Build succeeded
snowpatch_ozlabs/build-pmac32 success Build succeeded
snowpatch_ozlabs/checkpatch warning total: 0 errors, 0 warnings, 1 checks, 43 lines checked

Commit Message

Christopher M. Riedl May 17, 2019, 1:14 p.m. UTC 
Add support for disabling the kernel implemented spectre v2 mitigation
(count cache flush on context switch) via the nospectre_v2 and
mitigations=off cmdline options.

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Christopher M. Riedl <cmr@informatik.wtf>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
---
v3->v4:
	add support for new mitigations=off cmdline option

 arch/powerpc/kernel/security.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index e1c9cf079503..88ae6a9bdf74 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -28,7 +28,7 @@  static enum count_cache_flush_type count_cache_flush_type = COUNT_CACHE_FLUSH_NO
 bool barrier_nospec_enabled;
 static bool no_nospec;
 static bool btb_flush_enabled;
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64)
 static bool no_spectrev2;
 #endif
 
@@ -114,7 +114,7 @@  static __init int security_feature_debugfs_init(void)
 device_initcall(security_feature_debugfs_init);
 #endif /* CONFIG_DEBUG_FS */
 
-#ifdef CONFIG_PPC_FSL_BOOK3E
+#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64)
 static int __init handle_nospectre_v2(char *p)
 {
 	no_spectrev2 = true;
@@ -122,6 +122,9 @@  static int __init handle_nospectre_v2(char *p)
 	return 0;
 }
 early_param("nospectre_v2", handle_nospectre_v2);
+#endif /* CONFIG_PPC_FSL_BOOK3E || CONFIG_PPC_BOOK3S_64 */
+
+#ifdef CONFIG_PPC_FSL_BOOK3E
 void setup_spectre_v2(void)
 {
 	if (no_spectrev2 || cpu_mitigations_off())
@@ -399,7 +402,17 @@  static void toggle_count_cache_flush(bool enable)
 
 void setup_count_cache_flush(void)
 {
-	toggle_count_cache_flush(true);
+	bool enable = true;
+
+	if (no_spectrev2 || cpu_mitigations_off()) {
+		if (security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED)
+		    || security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED))
+			pr_warn("Spectre v2 mitigations not under software control, can't disable\n");
+
+		enable = false;
+	}
+
+	toggle_count_cache_flush(enable);
 }
 
 #ifdef CONFIG_DEBUG_FS