LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
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>,
	linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [Patch v3 07/13] x86/process Add arch_set_dumpable
Date: Thu, 18 Oct 2018 11:46:35 -0700	[thread overview]
Message-ID: <c8bb3ea2-d060-5cad-1544-ae5ff5f8fd3b@linux.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1810181522230.1647@nanos.tec.linutronix.de>

On 10/18/2018 06:28 AM, Thomas Gleixner wrote:

> 
> So now the obvious question. set_dumpable() operates on tsk->mm. i.e. it's
> a process wide operation. But arch_set_dumpable() operates on the task
> itself. What about the other tasks of that process?

I missed this part.

Fixing this is tricky as I don't see an easy way to
reverse map mm back to all tasks that use the same mm
to update their STIBP flags.

One possible solution is to not use STIBP flag for
non-dumpable processes.
We check during context switch whether
get_dumpable(prev) != get_dumpable(next) in addition
to STIBP flag changes to update SPEC_CTRL MSR and IBPB.

We will need to IPI all other CPUs to update
their SPEC_CTRL MSR if they are using the mm
that has dumpable property changes.

Any better suggestions?

Tim

> 
> Thanks,
> 
> 	tglx
> 


  reply	other threads:[~2018-10-18 18:46 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-17 17:59 [Patch v3 00/13] Provide process property based options to enable Spectre v2 userspace-userspace protection Tim Chen
2018-10-17 17:59 ` [Patch v3 01/13] x86/speculation: Clean up spectre_v2_parse_cmdline Tim Chen
2018-10-18 12:43   ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 02/13] x86/speculation: Remove unnecessary ret variable in cpu_show_common Tim Chen
2018-10-18 12:46   ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 03/13] x86/speculation: Add static key for Enhanced IBRS Tim Chen
2018-10-18 12:50   ` Thomas Gleixner
2018-10-26 16:58   ` Waiman Long
2018-10-26 18:15     ` Tim Chen
2018-10-28  9:32       ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 04/13] x86/speculation: Disable STIBP when enhanced IBRS is in use Tim Chen
2018-10-18 12:58   ` Thomas Gleixner
2018-10-26 17:00   ` Waiman Long
2018-10-26 18:18     ` Tim Chen
2018-10-26 18:29       ` Tim Chen
2018-10-17 17:59 ` [Patch v3 05/13] x86/smt: Create cpu_smt_enabled static key for SMT specific code Tim Chen
2018-10-18 13:03   ` Thomas Gleixner
2018-10-19  7:51   ` Peter Zijlstra
2018-10-17 17:59 ` [Patch v3 06/13] mm: Pass task instead of task->mm as argument to set_dumpable Tim Chen
2018-10-18 13:22   ` Thomas Gleixner
2018-10-19 20:02   ` Peter Zijlstra
2018-10-17 17:59 ` [Patch v3 07/13] x86/process Add arch_set_dumpable Tim Chen
2018-10-18 13:28   ` Thomas Gleixner
2018-10-18 18:46     ` Tim Chen [this message]
2018-10-19 19:12       ` Thomas Gleixner
2018-10-19 20:16         ` Thomas Gleixner
2018-10-22 23:55           ` Tim Chen
2018-10-17 17:59 ` [Patch v3 08/13] x86/speculation: Rename SSBD update functions Tim Chen
2018-10-18 13:37   ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 09/13] x86/speculation: Reorganize SPEC_CTRL MSR update Tim Chen
2018-10-18 13:47   ` Thomas Gleixner
2018-10-26 17:21   ` Waiman Long
2018-10-26 18:25     ` Tim Chen
2018-10-17 17:59 ` [Patch v3 10/13] x86/speculation: Add per thread STIBP flag Tim Chen
2018-10-18 13:53   ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 11/13] x86/speculation: Add Spectre v2 lite app to app protection mode Tim Chen
2018-10-18 15:12   ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 12/13] x86/speculation: Protect non-dumpable processes against Spectre v2 attack Tim Chen
2018-10-18 15:17   ` Thomas Gleixner
2018-10-26 17:46   ` Waiman Long
2018-10-26 18:10     ` Tim Chen
2018-10-17 17:59 ` [Patch v3 13/13] x86/speculation: Create PRCTL interface to restrict indirect branch speculation Tim Chen
2018-10-17 19:12   ` Randy Dunlap
2018-10-18 15:31   ` Thomas Gleixner
2018-10-19  7:57 ` [Patch v3 00/13] Provide process property based options to enable Spectre v2 userspace-userspace protection Peter Zijlstra
2018-10-19 16:43   ` Tim Chen
2018-10-19 18:38     ` Peter Zijlstra

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=c8bb3ea2-d060-5cad-1544-ae5ff5f8fd3b@linux.intel.com \
    --to=tim.c.chen@linux.intel.com \
    --cc=aarcange@redhat.com \
    --cc=ak@linux.intel.com \
    --cc=arjan@linux.intel.com \
    --cc=asit.k.mallick@intel.com \
    --cc=casey.schaufler@intel.com \
    --cc=dave.hansen@intel.com \
    --cc=dwmw@amazon.co.uk \
    --cc=jcm@redhat.com \
    --cc=jikos@kernel.org \
    --cc=jpoimboe@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=thomas.lendacky@amd.com \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).