From: Borislav Petkov <bp@alien8.de>
To: Thomas Gleixner <tglx@linutronix.de>,
Tom Lendacky <thomas.lendacky@amd.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jiri Kosina <jkosina@suse.cz>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
David Woodhouse <dwmw@amazon.co.uk>,
Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Casey Schaufler <casey.schaufler@intel.com>,
Asit Mallick <asit.k.mallick@intel.com>,
Arjan van de Ven <arjan@linux.intel.com>,
Jon Masters <jcm@redhat.com>, Waiman Long <longman9394@gmail.com>,
Greg KH <gregkh@linuxfoundation.org>,
Dave Stewart <david.c.stewart@intel.com>,
Kees Cook <keescook@chromium.org>
Subject: Re: [patch 15/24] x86/speculation: Add command line control for indirect branch speculation
Date: Thu, 22 Nov 2018 00:43:12 +0100 [thread overview]
Message-ID: <20181121234312.GI27559@zn.tnic> (raw)
In-Reply-To: <20181121201723.764150349@linutronix.de>
On Wed, Nov 21, 2018 at 09:14:45PM +0100, Thomas Gleixner wrote:
> Add command line control for application to application indirect branch
> speculation mitigations.
>
> The initial options are:
>
> - on: Unconditionally enabled
> - off: Unconditionally disabled
> -auto: Kernel selects mitigation (default off for now)
>
> When the spectre_v2= command line argument is either 'on' or 'off' this
> implies that the application to application control follows that state even
> if when a contradicting spectre_v2_app2app= argument is supplied.
>
> Originally-by: Tim Chen <tim.c.chen@linux.intel.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 22 +++
> arch/x86/include/asm/nospec-branch.h | 10 +
> arch/x86/kernel/cpu/bugs.c | 133 ++++++++++++++++++++----
> 3 files changed, 146 insertions(+), 19 deletions(-)
...
> +static void __init
> +spectre_v2_app2app_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
> +{
> + enum spectre_v2_app2app_mitigation mode = SPECTRE_V2_APP2APP_NONE;
> + bool smt_possible = IS_ENABLED(CONFIG_SMP);
> +
> + if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP))
> + return;
> +
> + if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
> + cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
> + smt_possible = false;
> +
> + switch (spectre_v2_parse_app2app_cmdline(v2_cmd)) {
> + case SPECTRE_V2_APP2APP_CMD_AUTO:
> + case SPECTRE_V2_APP2APP_CMD_NONE:
> + goto set_mode;
> + case SPECTRE_V2_APP2APP_CMD_FORCE:
> + mode = SPECTRE_V2_APP2APP_STRICT;
> + break;
> + }
> +
> + /* Initialize Indirect Branch Prediction Barrier */
> + if (boot_cpu_has(X86_FEATURE_IBPB)) {
> + setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
> + pr_info("Spectre v2 mitigation: Enabling Indirect Branch Prediction Barrier\n");
> + }
So AFAICT, if coming in here with AUTO, we won't enable IBPB and I
*think* AMD wants IBPB enabled. At least the whitepaper says:
"IBPB combined with Reptoline software support is the AMD recommended
setting for Linux mitigation of Google Project Zero Variant 2
(Spectre)."
from https://www.amd.com/en/corporate/security-updates
Tom, am I completely off base here?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-11-21 23:43 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-21 20:14 [patch 00/24] x86/speculation: Remedy the STIBP/IBPB overhead Thomas Gleixner
2018-11-21 20:14 ` [patch 01/24] x86/speculation: Update the TIF_SSBD comment Thomas Gleixner
2018-11-21 20:28 ` Linus Torvalds
2018-11-21 20:30 ` Thomas Gleixner
2018-11-21 20:33 ` Linus Torvalds
2018-11-21 22:48 ` Thomas Gleixner
2018-11-21 22:53 ` Borislav Petkov
2018-11-21 22:55 ` Thomas Gleixner
2018-11-21 22:55 ` Arjan van de Ven
2018-11-21 22:56 ` Borislav Petkov
2018-11-21 23:07 ` Borislav Petkov
2018-11-21 23:04 ` Josh Poimboeuf
2018-11-21 23:08 ` Borislav Petkov
2018-11-22 17:30 ` Josh Poimboeuf
2018-11-22 17:52 ` Borislav Petkov
2018-11-22 21:17 ` Thomas Gleixner
2018-11-21 20:14 ` [patch 02/24] x86/speculation: Clean up spectre_v2_parse_cmdline() Thomas Gleixner
2018-11-21 20:14 ` [patch 03/24] x86/speculation: Remove unnecessary ret variable in cpu_show_common() Thomas Gleixner
2018-11-21 20:14 ` [patch 04/24] x86/speculation: Reorganize cpu_show_common() Thomas Gleixner
2018-11-21 20:14 ` [patch 05/24] x86/speculation: Disable STIBP when enhanced IBRS is in use Thomas Gleixner
2018-11-21 20:33 ` Borislav Petkov
2018-11-21 20:36 ` Thomas Gleixner
2018-11-21 22:01 ` Thomas Gleixner
2018-11-21 20:14 ` [patch 06/24] x86/speculation: Rename SSBD update functions Thomas Gleixner
2018-11-21 20:14 ` [patch 07/24] x86/speculation: Reorganize speculation control MSRs update Thomas Gleixner
2018-11-21 20:14 ` [patch 08/24] sched/smt: Make sched_smt_present track topology Thomas Gleixner
2018-11-21 20:14 ` [patch 09/24] x86/Kconfig: Select SCHED_SMT if SMP enabled Thomas Gleixner
2018-11-21 20:14 ` [patch 10/24] sched/smt: Expose sched_smt_present static key Thomas Gleixner
2018-11-21 20:41 ` Thomas Gleixner
2018-11-21 20:14 ` [patch 11/24] x86/speculation: Rework SMT state change Thomas Gleixner
2018-11-21 20:14 ` [patch 12/24] x86/l1tf: Show actual SMT state Thomas Gleixner
2018-11-21 20:14 ` [patch 13/24] x86/speculation: Reorder the spec_v2 code Thomas Gleixner
2018-11-21 20:14 ` [patch 14/24] x86/speculation: Unify conditional spectre v2 print functions Thomas Gleixner
2018-11-22 7:59 ` Ingo Molnar
2018-11-21 20:14 ` [patch 15/24] x86/speculation: Add command line control for indirect branch speculation Thomas Gleixner
2018-11-21 23:43 ` Borislav Petkov [this message]
2018-11-22 8:14 ` Thomas Gleixner
2018-11-22 9:07 ` Thomas Gleixner
2018-11-22 9:18 ` Peter Zijlstra
2018-11-22 10:10 ` Borislav Petkov
2018-11-22 10:48 ` Thomas Gleixner
2018-11-21 20:14 ` [patch 16/24] x86/speculation: Prepare for per task indirect branch speculation control Thomas Gleixner
2018-11-22 7:57 ` Ingo Molnar
2018-11-21 20:14 ` [patch 17/24] x86/speculation: Move IBPB control out of switch_mm() Thomas Gleixner
2018-11-22 0:01 ` Andi Kleen
2018-11-22 7:42 ` Jiri Kosina
2018-11-22 9:18 ` Thomas Gleixner
2018-11-22 1:40 ` Tim Chen
2018-11-22 7:52 ` Ingo Molnar
2018-11-22 22:29 ` Thomas Gleixner
2018-11-21 20:14 ` [patch 18/24] x86/speculation: Avoid __switch_to_xtra() calls Thomas Gleixner
2018-11-22 1:23 ` Tim Chen
2018-11-22 7:44 ` Ingo Molnar
2018-11-21 20:14 ` [patch 19/24] ptrace: Remove unused ptrace_may_access_sched() and MODE_IBRS Thomas Gleixner
2018-11-21 20:14 ` [patch 20/24] x86/speculation: Split out TIF update Thomas Gleixner
2018-11-22 2:13 ` Tim Chen
2018-11-22 23:00 ` Thomas Gleixner
2018-11-23 7:37 ` Ingo Molnar
2018-11-26 18:35 ` Tim Chen
2018-11-26 21:55 ` Thomas Gleixner
2018-11-27 7:05 ` Jiri Kosina
2018-11-27 7:13 ` Thomas Gleixner
2018-11-27 7:30 ` Jiri Kosina
2018-11-27 12:52 ` Jiri Kosina
2018-11-27 13:18 ` Jiri Kosina
2018-11-27 21:57 ` Thomas Gleixner
2018-11-27 22:07 ` Jiri Kosina
2018-11-27 22:20 ` Jiri Kosina
2018-11-27 22:36 ` Thomas Gleixner
2018-11-28 1:50 ` Tim Chen
2018-11-28 10:43 ` Thomas Gleixner
2018-11-28 6:05 ` Jiri Kosina
2018-11-28 14:33 ` [tip:x86/pti] x86/speculation: Prevent stale SPEC_CTRL msr content tip-bot for Thomas Gleixner
2018-11-22 7:43 ` [patch 20/24] x86/speculation: Split out TIF update Ingo Molnar
2018-11-22 23:04 ` Thomas Gleixner
2018-11-23 7:37 ` Ingo Molnar
2018-11-21 20:14 ` [patch 21/24] x86/speculation: Prepare arch_smt_update() for PRCTL mode Thomas Gleixner
2018-11-22 7:34 ` Ingo Molnar
2018-11-22 23:17 ` Thomas Gleixner
2018-11-22 23:28 ` Jiri Kosina
2018-11-21 20:14 ` [patch 22/24] x86/speculation: Create PRCTL interface to restrict indirect branch speculation Thomas Gleixner
2018-11-22 7:10 ` Ingo Molnar
2018-11-22 9:03 ` Peter Zijlstra
2018-11-22 9:08 ` Thomas Gleixner
2018-11-22 12:26 ` Borislav Petkov
2018-11-22 12:33 ` Peter Zijlstra
2018-11-21 20:14 ` [patch 23/24] x86/speculation: Enable PRCTL mode for spectre_v2_app2app Thomas Gleixner
2018-11-22 7:17 ` Ingo Molnar
2018-11-21 20:14 ` [patch 24/24] x86/speculation: Add seccomp Spectre v2 app to app protection mode Thomas Gleixner
2018-11-22 2:24 ` Tim Chen
2018-11-22 7:26 ` Ingo Molnar
2018-11-22 23:45 ` Thomas Gleixner
2018-11-21 23:48 ` [patch 00/24] x86/speculation: Remedy the STIBP/IBPB overhead Tim Chen
2018-11-22 9:55 ` Thomas Gleixner
2018-11-22 9:45 ` Peter Zijlstra
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