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Date:   Fri, 12 Jul 2019 14:36:53 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Alexandre Chartre <alexandre.chartre@oracle.com>
Cc:     pbonzini@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de,
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        x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        konrad.wilk@oracle.com, jan.setjeeilers@oracle.com,
        liran.alon@oracle.com, jwadams@google.com, graf@amazon.de,
        rppt@linux.vnet.ibm.com, Paul Turner <pjt@google.com>
Subject: Re: [RFC v2 00/27] Kernel Address Space Isolation
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On Fri, Jul 12, 2019 at 02:17:20PM +0200, Alexandre Chartre wrote:
> On 7/12/19 1:44 PM, Peter Zijlstra wrote:

> > AFAIK3 this wants/needs to be combined with core-scheduling to be
> > useful, but not a single mention of that is anywhere.
> 
> No. This is actually an alternative to core-scheduling. Eventually, ASI
> will kick all sibling hyperthreads when exiting isolation and it needs to
> run with the full kernel page-table (note that's currently not in these
> patches).
> 
> So ASI can be seen as an optimization to disabling hyperthreading: instead
> of just disabling hyperthreading you run with ASI, and when ASI can't preserve
> isolation you will basically run with a single thread.

You can't do that without much of the scheduler changes present in the
core-scheduling patches.