From: "Christopher M. Riedl" <cmr@informatik.wtf>
To: linuxppc-dev@ozlabs.org
Cc: "Christopher M. Riedl" <cmr@informatik.wtf>, ajd@linux.ibm.com
Subject: [PATCH v3] powerpc/64s: support nospectre_v2 cmdline option
Date: Tue, 7 May 2019 07:43:55 -0500 [thread overview]
Message-ID: <20190507124355.25684-1-cmr@informatik.wtf> (raw)
Add support for disabling the kernel implemented spectre v2 mitigation
(count cache flush on context switch) via the nospectre_v2 cmdline
option.
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>
---
v2->v3:
Address mpe's nitpick
arch/powerpc/kernel/security.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index b33bafb8fcea..7005c50a991b 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
@@ -106,7 +106,7 @@ static __init int barrier_nospec_debugfs_init(void)
device_initcall(barrier_nospec_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;
@@ -114,6 +114,9 @@ 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)
@@ -391,7 +394,17 @@ 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) {
+ 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
--
2.21.0
reply other threads:[~2019-05-07 12:43 UTC|newest]
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