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Message-ID: <09b279683e1b5ba1759ac3e9f644d290564902d3.camel@suse.com>
Subject: Re: [RFC PATCH v4 00/19] Core scheduling v4
From:   Dario Faggioli <dfaggioli@suse.com>
To:     Vineeth Remanan Pillai <vpillai@digitalocean.com>,
        Tim Chen <tim.c.chen@linux.intel.com>
Cc:     Nishanth Aravamudan <naravamudan@digitalocean.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Paul Turner <pjt@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Greg Kerr <kerrnel@google.com>, Phil Auld <pauld@redhat.com>,
        Aaron Lu <aaron.lwe@gmail.com>,
        Aubrey Li <aubrey.intel@gmail.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Date:   Tue, 28 Jan 2020 03:40:09 +0100
In-Reply-To: <CANaguZAz+mw1Oi8ecZt+JuCWbf=g5UvKrdSvAeM82Z1c+9oWAw@mail.gmail.com>
References: <cover.1572437285.git.vpillai@digitalocean.com>
         <5e3cea14-28d1-bf1e-cabe-fb5b48fdeadc@linux.intel.com>
         <3c3c56c1-b8dc-652c-535e-74f6dcf45560@linux.intel.com>
         <CANaguZAz+mw1Oi8ecZt+JuCWbf=g5UvKrdSvAeM82Z1c+9oWAw@mail.gmail.com>
Organization: SUSE
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On Tue, 2020-01-14 at 10:40 -0500, Vineeth Remanan Pillai wrote:
> On Mon, Jan 13, 2020 at 8:12 PM Tim Chen <tim.c.chen@linux.intel.com>
>=20
> > As a side effect of the fix, each core can now operate in core-
> > scheduling
> > mode or non core-scheduling mode, depending on how many online SMT
> > threads it has.
> >=20
> > Vineet, are you guys planning to refresh v4 and update it to
> > v5?  Aubrey posted
> > a port to the latest kernel earlier.
> >=20
> We are investigating a performance issue
> with
> high overcommit io intensive workload and also we are trying to see
> if
> we can add synchronization during VMEXITs so that a guest vm cannot
> run
> run alongside with host kernel.=20
>
So, about this VMEXIT sync thing. I do agree that we should at least
try and do it (and assess performance).

I was wondering, however, what we think about core-scheduling + address
space isolation (or whatever it is/will be called). More specifically,
whether such a solution wouldn't be considered an equally safe setup
(at least for the virt use-cases, of course).

Basically, core-scheduling would prevent VM-to-VM attacks while ASI
would mitigate VM-to-hypervisor attacks.

Of course, such a solution would need to be fully implemented and
evaluated too... I just wanted to toss it around, mostly to know what
you think about it and whether or not it is already on your radar.

Thanks and Regards
--=20
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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<<This happens because _I_ choose it to happen!>> (Raistlin Majere)


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