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authorChristopher M. Riedl <cmr@informatik.wtf>2019-05-23 21:46:48 -0500
committerPaul Gortmaker <paul.gortmaker@windriver.com>2019-12-02 14:07:24 -0500
commitedebf91d36847ab6993af14c5ab60540ad41c5e0 (patch)
treec664ce932d2c15ea3cc68932d975ec8fc17ce8d4
parent69a94395116953979b57a24fb5075025f7cd1019 (diff)
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powerpc/64s: support nospectre_v2 cmdline option
commit d8f0e0b073e1ec52a05f0c2a56318b47387d2f10 upstream. 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> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190524024647.381-1-cmr@informatik.wtf Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
-rw-r--r--arch/powerpc/kernel/security.c19
1 files changed, 16 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index e1c9cf079503..7cfcb294b11c 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