From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, peterz@infradead.org,
david.c.stewart@intel.com, longman9394@gmail.com,
jkosina@suse.cz, ak@linux.intel.com, casey.schaufler@intel.com,
gregkh@linuxfoundation.org, arjan@linux.intel.com,
jcm@redhat.com, tglx@linutronix.de, thomas.lendacky@amd.com,
dave.hansen@intel.com, luto@kernel.org, hpa@zytor.com,
asit.k.mallick@intel.com, jpoimboe@redhat.com,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
dwmw@amazon.co.uk, aarcange@redhat.com, keescook@chromium.org,
tim.c.chen@linux.intel.com
Subject: [tip:x86/pti] x86/speculation: Enable prctl mode for spectre_v2_user
Date: Wed, 28 Nov 2018 06:35:23 -0800 [thread overview]
Message-ID: <tip-7cc765a67d8e04ef7d772425ca5a2a1e2b894c15@git.kernel.org> (raw)
In-Reply-To: <20181125185005.958421388@linutronix.de>
Commit-ID: 7cc765a67d8e04ef7d772425ca5a2a1e2b894c15
Gitweb: https://git.kernel.org/tip/7cc765a67d8e04ef7d772425ca5a2a1e2b894c15
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Sun, 25 Nov 2018 19:33:54 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 28 Nov 2018 11:57:13 +0100
x86/speculation: Enable prctl mode for spectre_v2_user
Now that all prerequisites are in place:
- Add the prctl command line option
- Default the 'auto' mode to 'prctl'
- When SMT state changes, update the static key which controls the
conditional STIBP evaluation on context switch.
- At init update the static key which controls the conditional IBPB
evaluation on context switch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Casey Schaufler <casey.schaufler@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Waiman Long <longman9394@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dave Stewart <david.c.stewart@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181125185005.958421388@linutronix.de
---
Documentation/admin-guide/kernel-parameters.txt | 7 ++++-
arch/x86/kernel/cpu/bugs.c | 41 +++++++++++++++++++------
2 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b6e5b33b9d75..a9b98a4e8789 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4236,9 +4236,14 @@
off - Unconditionally disable mitigations. Is
enforced by spectre_v2=off
+ prctl - Indirect branch speculation is enabled,
+ but mitigation can be enabled via prctl
+ per thread. The mitigation control state
+ is inherited on fork.
+
auto - Kernel selects the mitigation depending on
the available CPU features and vulnerability.
- Default is off.
+ Default is prctl.
Not specifying this option is equivalent to
spectre_v2_user=auto.
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 74359fff87fd..d0137d10f9a6 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -255,11 +255,13 @@ enum spectre_v2_user_cmd {
SPECTRE_V2_USER_CMD_NONE,
SPECTRE_V2_USER_CMD_AUTO,
SPECTRE_V2_USER_CMD_FORCE,
+ SPECTRE_V2_USER_CMD_PRCTL,
};
static const char * const spectre_v2_user_strings[] = {
[SPECTRE_V2_USER_NONE] = "User space: Vulnerable",
[SPECTRE_V2_USER_STRICT] = "User space: Mitigation: STIBP protection",
+ [SPECTRE_V2_USER_PRCTL] = "User space: Mitigation: STIBP via prctl",
};
static const struct {
@@ -270,6 +272,7 @@ static const struct {
{ "auto", SPECTRE_V2_USER_CMD_AUTO, false },
{ "off", SPECTRE_V2_USER_CMD_NONE, false },
{ "on", SPECTRE_V2_USER_CMD_FORCE, true },
+ { "prctl", SPECTRE_V2_USER_CMD_PRCTL, false },
};
static void __init spec_v2_user_print_cond(const char *reason, bool secure)
@@ -324,12 +327,15 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
smt_possible = false;
switch (spectre_v2_parse_user_cmdline(v2_cmd)) {
- case SPECTRE_V2_USER_CMD_AUTO:
case SPECTRE_V2_USER_CMD_NONE:
goto set_mode;
case SPECTRE_V2_USER_CMD_FORCE:
mode = SPECTRE_V2_USER_STRICT;
break;
+ case SPECTRE_V2_USER_CMD_AUTO:
+ case SPECTRE_V2_USER_CMD_PRCTL:
+ mode = SPECTRE_V2_USER_PRCTL;
+ break;
}
/* Initialize Indirect Branch Prediction Barrier */
@@ -340,6 +346,9 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
case SPECTRE_V2_USER_STRICT:
static_branch_enable(&switch_mm_always_ibpb);
break;
+ case SPECTRE_V2_USER_PRCTL:
+ static_branch_enable(&switch_mm_cond_ibpb);
+ break;
default:
break;
}
@@ -352,6 +361,12 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return;
+ /*
+ * If SMT is not possible or STIBP is not available clear the STIPB
+ * mode.
+ */
+ if (!smt_possible || !boot_cpu_has(X86_FEATURE_STIBP))
+ mode = SPECTRE_V2_USER_NONE;
set_mode:
spectre_v2_user = mode;
/* Only print the STIBP mode when SMT possible */
@@ -552,6 +567,15 @@ static void update_stibp_strict(void)
on_each_cpu(update_stibp_msr, NULL, 1);
}
+/* Update the static key controlling the evaluation of TIF_SPEC_IB */
+static void update_indir_branch_cond(void)
+{
+ if (sched_smt_active())
+ static_branch_enable(&switch_to_cond_stibp);
+ else
+ static_branch_disable(&switch_to_cond_stibp);
+}
+
void arch_smt_update(void)
{
/* Enhanced IBRS implies STIBP. No update required. */
@@ -567,6 +591,7 @@ void arch_smt_update(void)
update_stibp_strict();
break;
case SPECTRE_V2_USER_PRCTL:
+ update_indir_branch_cond();
break;
}
@@ -1038,7 +1063,8 @@ static char *stibp_state(void)
case SPECTRE_V2_USER_STRICT:
return ", STIBP: forced";
case SPECTRE_V2_USER_PRCTL:
- return "";
+ if (static_key_enabled(&switch_to_cond_stibp))
+ return ", STIBP: conditional";
}
return "";
}
@@ -1046,14 +1072,11 @@ static char *stibp_state(void)
static char *ibpb_state(void)
{
if (boot_cpu_has(X86_FEATURE_IBPB)) {
- switch (spectre_v2_user) {
- case SPECTRE_V2_USER_NONE:
- return ", IBPB: disabled";
- case SPECTRE_V2_USER_STRICT:
+ if (static_key_enabled(&switch_mm_always_ibpb))
return ", IBPB: always-on";
- case SPECTRE_V2_USER_PRCTL:
- return "";
- }
+ if (static_key_enabled(&switch_mm_cond_ibpb))
+ return ", IBPB: conditional";
+ return ", IBPB: disabled";
}
return "";
}
next prev parent reply other threads:[~2018-11-28 14:36 UTC|newest]
Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-25 18:33 [patch V2 00/28] x86/speculation: Remedy the STIBP/IBPB overhead Thomas Gleixner
2018-11-25 18:33 ` [patch V2 01/28] x86/speculation: Update the TIF_SSBD comment Thomas Gleixner
2018-11-28 14:20 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-11-29 14:27 ` [patch V2 01/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 02/28] x86/speculation: Clean up spectre_v2_parse_cmdline() Thomas Gleixner
2018-11-28 14:20 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-11-29 14:28 ` [patch V2 02/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 03/28] x86/speculation: Remove unnecessary ret variable in cpu_show_common() Thomas Gleixner
2018-11-28 14:21 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-11-29 14:28 ` [patch V2 03/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 04/28] x86/speculation: Reorganize cpu_show_common() Thomas Gleixner
2018-11-26 15:08 ` Borislav Petkov
2018-11-28 14:22 ` [tip:x86/pti] x86/speculation: Move STIPB/IBPB string conditionals out of cpu_show_common() tip-bot for Tim Chen
2018-11-29 14:29 ` [patch V2 04/28] x86/speculation: Reorganize cpu_show_common() Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 05/28] x86/speculation: Disable STIBP when enhanced IBRS is in use Thomas Gleixner
2018-11-28 14:22 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-11-29 14:35 ` [patch V2 05/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 06/28] x86/speculation: Rename SSBD update functions Thomas Gleixner
2018-11-26 15:24 ` Borislav Petkov
2018-11-28 14:23 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-29 14:37 ` [patch V2 06/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 07/28] x86/speculation: Reorganize speculation control MSRs update Thomas Gleixner
2018-11-26 15:47 ` Borislav Petkov
2018-11-28 14:23 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-11-29 14:41 ` [patch V2 07/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 08/28] sched/smt: Make sched_smt_present track topology Thomas Gleixner
2018-11-28 14:24 ` [tip:x86/pti] " tip-bot for Peter Zijlstra (Intel)
2018-11-29 14:42 ` [patch V2 08/28] " Konrad Rzeszutek Wilk
2018-11-29 14:50 ` Konrad Rzeszutek Wilk
2018-11-29 15:48 ` Peter Zijlstra
2018-11-25 18:33 ` [patch V2 09/28] x86/Kconfig: Select SCHED_SMT if SMP enabled Thomas Gleixner
2018-11-28 14:24 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-29 14:44 ` [patch V2 09/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 10/28] sched/smt: Expose sched_smt_present static key Thomas Gleixner
2018-11-28 14:25 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-29 14:44 ` [patch V2 10/28] " Konrad Rzeszutek Wilk
2018-11-25 18:33 ` [patch V2 11/28] x86/speculation: Rework SMT state change Thomas Gleixner
2018-11-28 14:26 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 12/28] x86/l1tf: Show actual SMT state Thomas Gleixner
2018-11-28 14:26 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 13/28] x86/speculation: Reorder the spec_v2 code Thomas Gleixner
2018-11-26 22:21 ` Borislav Petkov
2018-11-28 14:27 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 14/28] x86/speculation: Mark string arrays const correctly Thomas Gleixner
2018-11-28 14:27 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 15/28] x86/speculataion: Mark command line parser data __initdata Thomas Gleixner
2018-11-28 14:28 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 16/28] x86/speculation: Unify conditional spectre v2 print functions Thomas Gleixner
2018-11-28 14:29 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 17/28] x86/speculation: Add command line control for indirect branch speculation Thomas Gleixner
2018-11-28 14:29 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 18/28] x86/speculation: Prepare for per task indirect branch speculation control Thomas Gleixner
2018-11-27 17:25 ` Lendacky, Thomas
2018-11-27 19:51 ` Tim Chen
2018-11-28 9:39 ` Thomas Gleixner
2018-11-27 20:39 ` Thomas Gleixner
2018-11-27 20:42 ` Thomas Gleixner
2018-11-27 21:52 ` Lendacky, Thomas
2018-11-28 14:30 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-11-25 18:33 ` [patch V2 19/28] x86/process: Consolidate and simplify switch_to_xtra() code Thomas Gleixner
2018-11-26 18:30 ` Borislav Petkov
2018-11-28 14:30 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 20/28] x86/speculation: Avoid __switch_to_xtra() calls Thomas Gleixner
2018-11-28 14:31 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 21/28] x86/speculation: Prepare for conditional IBPB in switch_mm() Thomas Gleixner
2018-11-25 19:11 ` Thomas Gleixner
2018-11-25 20:53 ` Andi Kleen
2018-11-25 22:20 ` Thomas Gleixner
2018-11-25 23:04 ` Andy Lutomirski
2018-11-26 7:10 ` Thomas Gleixner
2018-11-26 13:36 ` Ingo Molnar
2018-11-26 3:07 ` Andi Kleen
2018-11-26 6:50 ` Thomas Gleixner
2018-11-28 14:31 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 22/28] ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS Thomas Gleixner
2018-11-28 14:32 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 23/28] x86/speculation: Split out TIF update Thomas Gleixner
2018-11-28 14:33 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 24/28] x86/speculation: Prepare arch_smt_update() for PRCTL mode Thomas Gleixner
2018-11-27 20:18 ` Lendacky, Thomas
2018-11-27 20:30 ` Thomas Gleixner
2018-11-27 21:20 ` Lendacky, Thomas
2018-11-28 14:34 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 25/28] x86/speculation: Add prctl() control for indirect branch speculation Thomas Gleixner
2018-11-28 14:34 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-25 18:33 ` [patch V2 26/28] x86/speculation: Enable prctl mode for spectre_v2_user Thomas Gleixner
2018-11-26 7:56 ` Dominik Brodowski
2018-11-28 14:35 ` tip-bot for Thomas Gleixner [this message]
2018-11-25 18:33 ` [patch V2 27/28] x86/speculation: Add seccomp Spectre v2 user space protection mode Thomas Gleixner
2018-11-25 19:35 ` Randy Dunlap
2018-11-25 20:40 ` Linus Torvalds
2018-11-25 20:52 ` Jiri Kosina
2018-11-25 22:28 ` Thomas Gleixner
2018-11-26 13:30 ` Ingo Molnar
2018-11-26 20:48 ` Andrea Arcangeli
2018-11-26 20:58 ` Thomas Gleixner
2018-11-26 21:52 ` Lendacky, Thomas
2018-11-27 0:37 ` Tim Chen
2018-12-04 1:38 ` Tim Chen
2018-12-04 8:39 ` Jiri Kosina
2018-12-04 9:43 ` Arjan van de Ven
2018-12-04 9:46 ` Arjan van de Ven
2018-12-04 17:20 ` Linus Torvalds
2018-12-04 18:58 ` Tim Chen
2018-11-28 14:35 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-12-04 18:45 ` [patch V2 27/28] " Dave Hansen
2018-11-25 18:33 ` [patch V2 28/28] x86/speculation: Provide IBPB always command line options Thomas Gleixner
2018-11-28 14:36 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
2018-11-26 13:37 ` [patch V2 00/28] x86/speculation: Remedy the STIBP/IBPB overhead Ingo Molnar
2018-11-28 14:24 ` Thomas Gleixner
2018-11-29 19:02 ` Tim Chen
2018-12-10 23:43 ` Pavel Machek
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