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=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID 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 EB144C433F4 for ; Wed, 19 Sep 2018 17:00:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 873502150B for ; Wed, 19 Sep 2018 17:00:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="N8kCvqx+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 873502150B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com 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 S1732724AbeISWj1 (ORCPT ); Wed, 19 Sep 2018 18:39:27 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:34921 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728254AbeISWj0 (ORCPT ); Wed, 19 Sep 2018 18:39:26 -0400 Received: by mail-wr1-f67.google.com with SMTP id j26-v6so6575244wre.2; Wed, 19 Sep 2018 10:00:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:openpgp:autocrypt:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=BQZK3LSAKm9Q/JEej51ize82XF99eUCDqrirO3cvFMM=; b=N8kCvqx+kF5FwnRdOhnpRR7sRilpMHTWOpeB7ISTni9fAvPGATzshNfkhQ927SnFc/ frgP5JdZbKBMKxWA7JySFf5grIoyvuel9TUJN5q7j+xVv/S0RFwBnX0HcAjwsTgxrUkN PILna744tpJK1AGP5BKYvF+K2HqA3H3AwCUrl0fyt+6NYuXY0W0tq3xvXDoR2WkBWGB9 FaeD8wSgJ0BracrJTj7TpVM0ClW979oOL9wbfid2K29CP316VWX/XhtFAtGL+pbeAnPD x13X+qLUNxlufDGIBBjeUpnDfsZ32PRldCKxyT5xR9T3r44fvsSUAXkrIoGZ2AjkCdqy gPDQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:subject:to:cc:references:from:openpgp :autocrypt:message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=BQZK3LSAKm9Q/JEej51ize82XF99eUCDqrirO3cvFMM=; b=jIPBCaDC3pjcaO8HdYoKZBdN5tDZROwNvcr/01RqA+tNF0XegjoZ6RpMI9FOEGb9Tx qu6vCLSmKM7tP8t4NFBKwGqX/lp4XEMNTkIByWpq/2lamiRpvV6S6SxAFZHtUZHm9RGU bu9gVhsBkps5MyQyo3EaKqljBKqg/T0J0oO0aDRHSp6qDKJ3u5XmgFQh5EU2TPj6R9Gy r2pxtkLppoaHel5vfUpPJsKBRC31LcsoMMq03kD5kO863lnd5Ti8sTx0Ix4kXx1xTzsl b4Ys3zd5V6s3/YHVMB+S8r24Whhp1uD446//avi4OnbS/lG4133nXwU47ASuShk8VSf/ UJwg== X-Gm-Message-State: APzg51DsP5gqLvuXFddvP4bUH1Mjm5N1XQWzWnWhTq6z9aTIHeFgd3hB ebki+ERaA0Ek2NBrHNCcdkwaovr8 X-Google-Smtp-Source: ANB0VdZipJ1KjDsTK6bEu0UIs2Kz2Vltj9HR71BPF/lziBc2SxSmnc+uU/ZWWtkCpqFmSSzTSDFYcg== X-Received: by 2002:a5d:4250:: with SMTP id s16-v6mr28759409wrr.260.1537376437234; Wed, 19 Sep 2018 10:00:37 -0700 (PDT) Received: from [192.168.10.165] (94-36-187-248.adsl-ull.clienti.tiscali.it. [94.36.187.248]) by smtp.googlemail.com with ESMTPSA id f18-v6sm20619572wrw.32.2018.09.19.10.00.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Sep 2018 10:00:36 -0700 (PDT) Subject: Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state To: Sebastian Andrzej Siewior Cc: Rik van Riel , linux-kernel@vger.kernel.org, x86@kernel.org, Andy Lutomirski , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , kvm@vger.kernel.org, "Jason A. Donenfeld" References: <8e5b64e4-b3e6-f884-beb6-b7b69ab2d8c1@redhat.com> <20180914203501.qibhpmueosvkr74w@linutronix.de> <20180918142701.atfb4ul45k7tl6ew@linutronix.de> <7e9a13f3-93f5-fe4a-20d2-f4f9407bd43b@redhat.com> <83e271e1298d603c1105dd0dbea32d67da9cf1fa.camel@surriel.com> <36e8493f-f994-e885-8fe6-2f0d4a9904a1@redhat.com> <20180918160419.2zeru6xnufxixcax@linutronix.de> <11aa7d0f4ba36eff8b61a5dc1bd35ee5195fd576.camel@surriel.com> <20180919165719.iepvc7tg6aabp5mm@linutronix.de> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0f UGFvbG8gQm9uemluaSA8Ym9uemluaUBnbnUub3JnPsLBTQQTAQIAIwUCVEJ7AwIbAwcLCQgH AwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEH4VEAzNNmmxNcwOniaZVLsuy1lW/ntYCA0Caz0i sHpmecK8aWlvL9wpQCk4GlOX9L1emyYXZPmzIYB0IRqmSzAlZxi+A2qm9XOxs5gJ2xqMEXX5 FMtUH3kpkWWJeLqe7z0EoQdUI4EG988uv/tdZyqjUn2XJE+K01x7r3MkUSFz/HZKZiCvYuze VlS0NTYdUt5jBXualvAwNKfxEkrxeHjxgdFHjYWhjflahY7TNRmuqPM/Lx7wAuyoDjlYNE40 Z+Kun4/KjMbjgpcF4Nf3PJQR8qXI6p3so2qsSn91tY7DFSJO6v2HwFJkC2jU95wxfNmTEUZc znXahYbVOwCDJRuPrE5GKFd/XJU9u5hNtr/uYipHij01WXal2cce1S5mn1/HuM1yo1u8xdHy IupCd57EWI948e8BlhpujUCU2tzOb2iYS0kpmJ9/oLVZrOcSZCcCl2P0AaCAsj59z2kwQS9D du0WxUs8waso0Qq6tDEHo8yLCOJDzSz4oojTtWe4zsulVnWV+wu70AioemAT8S6JOtlu60C5 dHgQUD1Tp+ReXpDKXmjbASJx4otvW0qah3o6JaqO79tbDqIvncu3tewwp6c85uZd48JnIOh3 utBAu684nJakbbvZUGikJfxd887ATQRUQnHuAQgAx4dxXO6/Zun0eVYOnr5GRl76+2UrAAem Vv9Yfn2PbDIbxXqLff7oyVJIkw4WdhQIIvvtu5zH24iYjmdfbg8iWpP7NqxUQRUZJEWbx2CR wkMHtOmzQiQ2tSLjKh/cHeyFH68xjeLcinR7jXMrHQK+UCEw6jqi1oeZzGvfmxarUmS0uRuf fAb589AJW50kkQK9VD/9QC2FJISSUDnRC0PawGSZDXhmvITJMdD4TjYrePYhSY4uuIV02v02 8TVAaYbIhxvDY0hUQE4r8ZbGRLn52bEzaIPgl1p/adKfeOUeMReg/CkyzQpmyB1TSk8lDMxQ zCYHXAzwnGi8WU9iuE1P0wARAQABwsEzBBgBAgAJBQJUQnHuAhsMAAoJEH4VEAzNNmmxp1EO oJy0uZggJm7gZKeJ7iUpeX4eqUtqelUw6gU2daz2hE/jsxsTbC/w5piHmk1H1VWDKEM4bQBT uiJ0bfo55SWsUNN+c9hhIX+Y8LEe22izK3w7mRpvGcg+/ZRG4DEMHLP6JVsv5GMpoYwYOmHn plOzCXHvmdlW0i6SrMsBDl9rw4AtIa6bRwWLim1lQ6EM3PWifPrWSUPrPcw4OLSwFk0CPqC4 HYv/7ZnASVkR5EERFF3+6iaaVi5OgBd81F1TCvCX2BEyIDRZLJNvX3TOd5FEN+lIrl26xecz 876SvcOb5SL5SKg9/rCBufdPSjojkGFWGziHiFaYhbuI2E+NfWLJtd+ZvWAAV+O0d8vFFSvr iy9enJ8kxJwhC0ECbSKFY+W1eTIhMD3aeAKY90drozWEyHhENf4l/V+Ja5vOnW+gCDQkGt2Y 1lJAPPSIqZKvHzGShdh8DduC0U3xYkfbGAUvbxeepjgzp0uEnBXfPTy09JGpgWbg0w91GyfT /ujKaGd4vxG2Ei+MMNDmS1SMx7wu0evvQ5kT9NPzyq8R2GIhVSiAd2jioGuTjX6AZCFv3ToO 53DliFMkVTecLptsXaesuUHgL9dKIfvpm+rNXRn9wAwGjk0X/A== Message-ID: <099b9f82-e162-c91a-bc51-aa1ac0cd50aa@redhat.com> Date: Wed, 19 Sep 2018 19:00:34 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180919165719.iepvc7tg6aabp5mm@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/09/2018 18:57, Sebastian Andrzej Siewior wrote: > On 2018-09-19 07:55:51 [+0200], Paolo Bonzini wrote: >> A kthread can do use_mm/unuse_mm. > > indeed. The FPU struct for the kernel thread isn't valid / does not > contain the expected PKRU value. So loading the pkru value from the > struct FPU does not work as expected. We could set it to 0 for a kernel > thread so we don't end up with a random value. > If we want to get this usecase working then we would have to move pkru > value from FPU to mm_struct and consider it in use_mm(). Do we want > this? As a start, I think keeping it in the FPU struct but loading it unconditionally will work. kthreads will not obey PKU but it will be better already. I honestly don't know if PKRU should be per-mm, I don't know mm very well despite my brilliant observation above. :) Paolo