* [PATCH v5] powerpc/64s: support nospectre_v2 cmdline option
@ 2019-05-24 2:46 Christopher M. Riedl
2019-06-05 7:42 ` Andrew Donnellan
2019-08-28 4:24 ` Michael Ellerman
0 siblings, 2 replies; 4+ messages in thread
From: Christopher M. Riedl @ 2019-05-24 2:46 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Christopher M. Riedl, Andrew Donnellan
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>
---
v4->v5:
Fix checkpatch complaint
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 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
--
2.21.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v5] powerpc/64s: support nospectre_v2 cmdline option
2019-05-24 2:46 [PATCH v5] powerpc/64s: support nospectre_v2 cmdline option Christopher M. Riedl
@ 2019-06-05 7:42 ` Andrew Donnellan
2019-07-09 8:08 ` Andrew Donnellan
2019-08-28 4:24 ` Michael Ellerman
1 sibling, 1 reply; 4+ messages in thread
From: Andrew Donnellan @ 2019-06-05 7:42 UTC (permalink / raw)
To: Christopher M. Riedl, linuxppc-dev
On 24/5/19 12:46 pm, Christopher M. Riedl wrote:
> 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>
snowpatch is whinging about this breaking the build for some reason...
https://patchwork.ozlabs.org/patch/1104583/
> ---
> v4->v5:
> Fix checkpatch complaint
> 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 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
>
--
Andrew Donnellan OzLabs, ADL Canberra
ajd@linux.ibm.com IBM Australia Limited
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v5] powerpc/64s: support nospectre_v2 cmdline option
2019-06-05 7:42 ` Andrew Donnellan
@ 2019-07-09 8:08 ` Andrew Donnellan
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Donnellan @ 2019-07-09 8:08 UTC (permalink / raw)
To: Christopher M. Riedl, linuxppc-dev
On 5/6/19 5:42 pm, Andrew Donnellan wrote:
> On 24/5/19 12:46 pm, Christopher M. Riedl wrote:
>> 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>
>
> snowpatch is whinging about this breaking the build for some reason...
> https://patchwork.ozlabs.org/patch/1104583/
Upon further inspection, it appears this was bogus, and now snowpatch is
passing it happily.
--
Andrew Donnellan OzLabs, ADL Canberra
ajd@linux.ibm.com IBM Australia Limited
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v5] powerpc/64s: support nospectre_v2 cmdline option
2019-05-24 2:46 [PATCH v5] powerpc/64s: support nospectre_v2 cmdline option Christopher M. Riedl
2019-06-05 7:42 ` Andrew Donnellan
@ 2019-08-28 4:24 ` Michael Ellerman
1 sibling, 0 replies; 4+ messages in thread
From: Michael Ellerman @ 2019-08-28 4:24 UTC (permalink / raw)
To: Christopher M. Riedl, linuxppc-dev; +Cc: Christopher M. Riedl, Andrew Donnellan
On Fri, 2019-05-24 at 02:46:48 UTC, "Christopher M. Riedl" wrote:
> 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>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/d8f0e0b073e1ec52a05f0c2a56318b47387d2f10
cheers
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-06-05 7:42 ` Andrew Donnellan
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2019-08-28 4:24 ` Michael Ellerman
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