linux-kernel - Re: [PATCH v8 -tip 13/26] kernel/entry: Add support for core-wide protection of kernel-mode

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Date:   Mon, 2 Nov 2020 19:20:10 -0500
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, mingo@...nel.org,
        torvalds@...ux-foundation.org, fweisbec@...il.com,
        keescook@...omium.org, kerrnel@...gle.com,
        Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>, vineeth@...byteword.org,
        Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Agata Gruza <agata.gruza@...el.com>,
        Antonio Gomez Iglesias <antonio.gomez.iglesias@...el.com>,
        graf@...zon.com, konrad.wilk@...cle.com, dfaggioli@...e.com,
        pjt@...gle.com, rostedt@...dmis.org, derkling@...gle.com,
        benbjiang@...cent.com,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        James.Bottomley@...senpartnership.com, OWeisse@...ch.edu,
        Dhaval Giani <dhaval.giani@...cle.com>,
        Junaid Shahid <junaids@...gle.com>, jsbarnes@...gle.com,
        chris.hyser@...cle.com, Aubrey Li <aubrey.li@...ux.intel.com>,
        Tim Chen <tim.c.chen@...el.com>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH v8 -tip 13/26] kernel/entry: Add support for core-wide
 protection of kernel-mode

On Mon, Oct 19, 2020 at 08:41:04PM -0700, Randy Dunlap wrote:
> On 10/19/20 6:43 PM, Joel Fernandes (Google) wrote:
> > 
> > ---
> >   .../admin-guide/kernel-parameters.txt         |   7 +
> >   include/linux/entry-common.h                  |   2 +-
> >   include/linux/sched.h                         |  12 +
> >   kernel/entry/common.c                         |  25 +-
> >   kernel/sched/core.c                           | 229 ++++++++++++++++++
> >   kernel/sched/sched.h                          |   3 +
> >   6 files changed, 275 insertions(+), 3 deletions(-)
> > 
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 3236427e2215..48567110f709 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -4678,6 +4678,13 @@
> >   	sbni=		[NET] Granch SBNI12 leased line adapter
> > +	sched_core_protect_kernel=
> 
> Needs a list of possible values after '=', along with telling us
> what the default value/setting is.

Ok, I made it the following:

        sched_core_protect_kernel=
                        [SCHED_CORE] Pause SMT siblings of a core running in
                        user mode, if at least one of the siblings of the core
                        is running in kernel mode. This is to guarantee that
                        kernel data is not leaked to tasks which are not trusted
                        by the kernel. A value of 0 disables protection, 1
                        enables protection. The default is 1.

thanks,

 - Joel


> > +			[SCHED_CORE] Pause SMT siblings of a core running in
> > +			user mode, if at least one of the siblings of the core
> > +			is running in kernel mode. This is to guarantee that
> > +			kernel data is not leaked to tasks which are not trusted
> > +			by the kernel.
> > +
> 
> 
> thanks.