From: Tim Chen <tim.c.chen@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jikos@kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
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>,
linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [Patch v5 11/16] x86/speculation: Add Spectre v2 app to app protection modes
Date: Mon, 19 Nov 2018 16:08:42 -0800 [thread overview]
Message-ID: <eb6a2309-40ee-ed89-aefe-7834fd0e4139@linux.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1811191423140.1537@nanos.tec.linutronix.de>
On 11/19/2018 05:32 AM, Thomas Gleixner wrote:
> Tim,
>
> On Fri, 16 Nov 2018, Tim Chen wrote:
>
>> Add new protection modes for Spectre v2 mitigations against
>> Spectre v2 attacks on user processes. There are three modes:
>>
>> strict mode:
>> In this mode, IBPB and STIBP are deployed full
>> time to protect all processes.
>>
>> lite mode:
>> In this mode, IBPB and STIBP are only deployed on
>> processes marked with TIF_STIBP flag.
>>
>> none mode:
>> In this mode, no mitigations are deployed.
>>
>> The protection mode can be specified by the spectre_v2_app2app
>> boot parameter with the following semantics:
>>
>> spectre_v2_app2app=
>> off - Turn off mitigation
>> lite - Protect processes which are marked non-dumpable
>> strict - Protect all processes
>> auto - Kernel selects the mode
>
> Is there any reason why we need yet another naming convention?
>
> pti= on, off, auto
>
> spectre_v2= on, off, auto
>
> spec_store_bypass_disable = on, off, auto, prctl, seccomp
The "on" option is set by spectre_v2=on so is not specified here.
What will you like to name the "lite" and "strict" option instead?
>
>
>> Not specifying this option is equivalent to
>> spectre_v2_app2app=auto.
>
> For better understanding it's nowhere documented what auto does.
I'll add the documentation.
>
>> + spectre_v2_app2app=
>> + [X86] Control mitigation of Spectre variant 2
>> + application to application (indirect branch speculation)
>> + vulnerability.
>> +
>> + off - Unconditionally disable mitigations
>> + lite - Protect tasks which have requested restricted
>> + indirect branch speculation via the
>> + PR_SET_SPECULATION_CTRL prctl().
>> + strict - Protect all processes
>> + auto - Kernel selects the mode
>> +
>> + Not specifying this option is equivalent to
>> + spectre_v2_app2app=auto.
>> +
>> + Setting spectre_v2=off will also turn off this mitigation.
>> +
>> + Setting spectre_v2=on implies unconditionally enabling
>> + this mitigation.
>
> Can we please have a full documentation for all the spectre_v2 stuff
> similar to l1tf?
>
Sure. Can we do that as a separate patch? I'll need some time
and internal review for any spectre_v2 documentation that's produced.
Tim
next prev parent reply other threads:[~2018-11-20 0:08 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-17 1:53 [Patch v5 00/16] Provide task property based options to enable Spectre v2 userspace-userspace protection Tim Chen
2018-11-17 1:53 ` [Patch v5 01/16] x86/speculation: Clean up spectre_v2_parse_cmdline() Tim Chen
2018-11-17 1:53 ` [Patch v5 02/16] x86/speculation: Remove unnecessary ret variable in cpu_show_common() Tim Chen
2018-11-17 1:53 ` [Patch v5 03/16] x86/speculation: Reorganize cpu_show_common() Tim Chen
2018-11-17 1:53 ` [Patch v5 04/16] x86/speculation: Add X86_FEATURE_USE_IBRS_ENHANCED Tim Chen
2018-11-17 1:53 ` [Patch v5 05/16] x86/speculation: Disable STIBP when enhanced IBRS is in use Tim Chen
2018-11-17 1:53 ` [Patch v5 06/16] x86/speculation: Rename SSBD update functions Tim Chen
2018-11-17 1:53 ` [Patch v5 07/16] x86/speculation: Reorganize speculation control MSRs update Tim Chen
2018-11-17 1:53 ` [Patch v5 08/16] smt: Create cpu_smt_enabled static key for SMT specific code Tim Chen
2018-11-19 12:58 ` Thomas Gleixner
2018-11-19 20:50 ` Tim Chen
2018-11-19 14:57 ` Peter Zijlstra
2018-11-19 18:08 ` Tim Chen
2018-11-19 19:03 ` Thomas Gleixner
2018-11-19 19:25 ` Tim Chen
2018-11-17 1:53 ` [Patch v5 09/16] x86/smt: Convert cpu_smt_control check to cpu_smt_enabled static key Tim Chen
2018-11-19 12:48 ` Thomas Gleixner
2018-11-19 12:59 ` Thomas Gleixner
2018-11-17 1:53 ` [Patch v5 10/16] x86/speculation: Turn on or off STIBP according to a task's TIF_STIBP Tim Chen
2018-11-17 1:53 ` [Patch v5 11/16] x86/speculation: Add Spectre v2 app to app protection modes Tim Chen
2018-11-17 9:47 ` Jiri Kosina
2018-11-18 22:59 ` Jiri Kosina
2018-11-19 13:36 ` Thomas Gleixner
2018-11-19 13:49 ` Jiri Kosina
2018-11-19 13:51 ` Thomas Gleixner
2018-11-19 14:00 ` Jiri Kosina
2018-11-19 18:31 ` Tim Chen
2018-11-19 19:32 ` Andrea Arcangeli
2018-11-19 19:39 ` Jiri Kosina
2018-11-19 21:40 ` Andrea Arcangeli
2018-11-19 21:33 ` Dave Hansen
2018-11-19 23:16 ` Andrea Arcangeli
2018-11-19 23:25 ` Dave Hansen
2018-11-19 23:45 ` Andrea Arcangeli
2018-11-20 0:22 ` Thomas Gleixner
2018-11-19 13:32 ` Thomas Gleixner
2018-11-20 0:08 ` Tim Chen [this message]
2018-11-20 0:30 ` Thomas Gleixner
2018-11-20 1:14 ` Tim Chen
2018-11-20 1:17 ` Andi Kleen
2018-11-19 15:00 ` Thomas Gleixner
2018-11-19 18:27 ` Tim Chen
2018-11-19 18:31 ` Jiri Kosina
2018-11-19 20:21 ` Thomas Gleixner
2018-11-19 22:44 ` Tim Chen
2018-11-19 20:46 ` Thomas Gleixner
2018-11-19 20:55 ` Jiri Kosina
2018-11-19 21:12 ` Thomas Gleixner
2018-11-19 22:48 ` Tim Chen
2018-11-19 23:01 ` Thomas Gleixner
2018-11-19 23:23 ` Jiri Kosina
2018-11-20 0:00 ` Thomas Gleixner
2018-11-20 0:24 ` Tim Chen
2018-11-19 23:39 ` Dave Hansen
2018-11-19 23:49 ` Jiri Kosina
2018-11-20 0:02 ` Thomas Gleixner
2018-11-17 1:53 ` [Patch v5 12/16] x86/speculation: Create PRCTL interface to restrict indirect branch speculation Tim Chen
2018-11-17 9:53 ` Jiri Kosina
2018-11-19 18:29 ` Tim Chen
2018-11-17 1:53 ` [Patch v5 13/16] security: Update speculation restriction of a process when modifying its dumpability Tim Chen
2018-11-17 1:53 ` [Patch v5 14/16] x86/speculation: Use STIBP to restrict speculation on non-dumpable task Tim Chen
2018-11-17 1:53 ` [Patch v5 15/16] x86/speculation: Update comment on TIF_SSBD Tim Chen
2018-11-17 1:53 ` [Patch v5 16/16] x86: Group thread info flags by functionality Tim Chen
2018-11-17 9:34 ` [Patch v5 00/16] Provide task property based options to enable Spectre v2 userspace-userspace protection Jiri Kosina
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