From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33B7BECDE32 for ; Wed, 17 Oct 2018 12:17:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E217B2150F for ; Wed, 17 Oct 2018 12:17:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E217B2150F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727103AbeJQUMf (ORCPT ); Wed, 17 Oct 2018 16:12:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:56612 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726961AbeJQUMf (ORCPT ); Wed, 17 Oct 2018 16:12:35 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 89EC1AF00; Wed, 17 Oct 2018 12:17:07 +0000 (UTC) Date: Wed, 17 Oct 2018 14:17:05 +0200 From: Michal Hocko To: Pavel Machek Cc: vbabka@suse.cz, hpa@zytor.com, torvalds@linux-foundation.org, ak@linux.intel.com, dave.hansen@intel.com, kernel list , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de Subject: Re: l1tf: Kernel suggests I throw away third of my memory. I'd rather not Message-ID: <20181017121705.GQ18839@dhcp22.suse.cz> References: <20181017105610.GA4260@amd> <20181017111544.GO18839@dhcp22.suse.cz> <20181017113226.GA5176@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181017113226.GA5176@amd> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 17-10-18 13:32:26, Pavel Machek wrote: [...] > > > Now question is... can we do better? Kernel stores information about > > > swapped-out pages there, right? That sounds like a cool hack, but > > > maybe it is time to get rid of that hack? > > > > Patches are welcome. > > Cooperation will be needed if you want to see patches. As > in... answering the questions above. The question is whether that is really worth it. L1TF is mostly about virtual environments. If you are running in a native HW then I wouldn't lose much sleep over it. a) pfns stored in PROT_NONE entries are controlled by the OS b) swap based attacks with something interesting in L1$ colliding with the swap entry is theoretical at best. -- Michal Hocko SUSE Labs