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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 19DDFC433F4 for ; Wed, 19 Sep 2018 05:56:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE282208A3 for ; Wed, 19 Sep 2018 05:55:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE282208A3 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 S1730826AbeISLcP (ORCPT ); Wed, 19 Sep 2018 07:32:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51988 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726827AbeISLcP (ORCPT ); Wed, 19 Sep 2018 07:32:15 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 14C664628E; Wed, 19 Sep 2018 05:55:56 +0000 (UTC) Received: from [10.36.116.157] (ovpn-116-157.ams2.redhat.com [10.36.116.157]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A143B1C956; Wed, 19 Sep 2018 05:55:53 +0000 (UTC) Subject: Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state To: Rik van Riel , Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Andy Lutomirski , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , kvm@vger.kernel.org, "Jason A. Donenfeld" References: <20180912133353.20595-1-bigeasy@linutronix.de> <20180912133353.20595-5-bigeasy@linutronix.de> <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> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; prefer-encrypt=mutual; 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: Date: Wed, 19 Sep 2018 07:55:51 +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: <11aa7d0f4ba36eff8b61a5dc1bd35ee5195fd576.camel@surriel.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="kFn7v2RuT0vkIFRIc79HFRdzcUXROYw3u" X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 19 Sep 2018 05:55:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --kFn7v2RuT0vkIFRIc79HFRdzcUXROYw3u Content-Type: multipart/mixed; boundary="CQMnCj40IxSZ8DheTDYHXgPccWto4rtio"; protected-headers="v1" From: Paolo Bonzini To: Rik van Riel , Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Andy Lutomirski , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , kvm@vger.kernel.org, "Jason A. Donenfeld" Message-ID: Subject: Re: [RFC PATCH 04/10 v2 ] x86/fpu: eager switch PKRU state References: <20180912133353.20595-1-bigeasy@linutronix.de> <20180912133353.20595-5-bigeasy@linutronix.de> <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> In-Reply-To: <11aa7d0f4ba36eff8b61a5dc1bd35ee5195fd576.camel@surriel.com> --CQMnCj40IxSZ8DheTDYHXgPccWto4rtio Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 18/09/2018 19:29, Rik van Riel wrote: > On Tue, 2018-09-18 at 18:04 +0200, Sebastian Andrzej Siewior wrote: >> On 2018-09-18 17:29:52 [+0200], Paolo Bonzini wrote: >>>> I don't think it matters what the PKRU state is >>>> for kernel threads, since kernel PTEs should not >>>> be using protection keys anyway. >>> >>> What about copy_from/to_user? >> >> This doesn't work for a kernel thread, does it? I mean they share the >> init's MM and never do copy_{from|to}_user. >=20 > Indeed, copy_from/to_user only works if current->mm > points at an mm_struct with userspace memory. A kthread can do use_mm/unuse_mm. Paolo --CQMnCj40IxSZ8DheTDYHXgPccWto4rtio-- --kFn7v2RuT0vkIFRIc79HFRdzcUXROYw3u Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEE8TM4V0tmI4mGbHaCv/vSX3jHroMFAluh5OcACgkQv/vSX3jH roPXsQgArb935hs76xneoqX0DuG+hroy/B+5wb6HPWpZpY1wVtCHBCd7rW832GjS 3u4+hXrp+oKGt1RA4Zmu8HpPU6rXM2vYfKZS4tJog7E51ApCFweIwBmvdLsG8vRH YbA6fcEcvAeDzYtNZBNnPJYDJUoJDk6KcO5k3rDKLOUJpDSISDuVhCpQQbAcTdMr Ch1QeEADNM/S/WcjMPE3QRKVsGwbNaNOm5t3uS8dp4l2vBbyvfvs5PkXbI3RaUt2 vPe0GJyBjeuXUgMJar3JGtdMXpAn+uxbIOFFDXru9eQoPVn5mGPDepMjxy5tvoIT d/XAYUYTY78SZUVfqtxudITLSbhcVw== =Qeo7 -----END PGP SIGNATURE----- --kFn7v2RuT0vkIFRIc79HFRdzcUXROYw3u--