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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 5F4DAC33CB1 for ; Wed, 15 Jan 2020 11:09:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2306D222C3 for ; Wed, 15 Jan 2020 11:09:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2306D222C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9A84B8E0011; Wed, 15 Jan 2020 06:09:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 95AC68E0003; Wed, 15 Jan 2020 06:09:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86F358E0011; Wed, 15 Jan 2020 06:09:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0058.hostedemail.com [216.40.44.58]) by kanga.kvack.org (Postfix) with ESMTP id 704B28E0003 for ; Wed, 15 Jan 2020 06:09:54 -0500 (EST) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 2BACC1263 for ; Wed, 15 Jan 2020 11:09:54 +0000 (UTC) X-FDA: 76379598708.09.men94_56690d434ba40 X-HE-Tag: men94_56690d434ba40 X-Filterd-Recvd-Size: 3091 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Wed, 15 Jan 2020 11:09:53 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id BAB13AC81; Wed, 15 Jan 2020 11:09:51 +0000 (UTC) Subject: Re: [PATCH v1 1/4] kasan: introduce set_pmd_early_shadow() To: Sergey Dyasli Cc: xen-devel@lists.xen.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Boris Ostrovsky , Stefano Stabellini , George Dunlap , Ross Lagerwall , Andrew Morton References: <20200108152100.7630-1-sergey.dyasli@citrix.com> <20200108152100.7630-2-sergey.dyasli@citrix.com> <96c2414e-91fb-5a28-44bc-e30d2daabec5@citrix.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <6f643816-a7dc-f3bb-d521-b6ac104918d6@suse.com> Date: Wed, 15 Jan 2020 12:09:50 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <96c2414e-91fb-5a28-44bc-e30d2daabec5@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 15.01.20 11:54, Sergey Dyasli wrote: > Hi Juergen, > > On 08/01/2020 15:20, Sergey Dyasli wrote: >> It is incorrect to call pmd_populate_kernel() multiple times for the >> same page table. Xen notices it during kasan_populate_early_shadow(): >> >> (XEN) mm.c:3222:d155v0 mfn 3704b already pinned >> >> This happens for kasan_early_shadow_pte when USE_SPLIT_PTE_PTLOCKS is >> enabled. Fix this by introducing set_pmd_early_shadow() which calls >> pmd_populate_kernel() only once and uses set_pmd() afterwards. >> >> Signed-off-by: Sergey Dyasli > > Looks like the plan to use set_pmd() directly has failed: it's an > arch-specific function and can't be used in arch-independent code > (as kbuild test robot has proven). > > Do you see any way out of this other than disabling SPLIT_PTE_PTLOCKS > for PV KASAN? Change set_pmd_early_shadow() like the following: #ifdef CONFIG_XEN_PV static inline void set_pmd_early_shadow(pmd_t *pmd, pte_t *early_shadow) { static bool pmd_populated = false; if (likely(pmd_populated)) { set_pmd(pmd, __pmd(__pa(early_shadow) | _PAGE_TABLE)); } else { pmd_populate_kernel(&init_mm, pmd, early_shadow); pmd_populated = true; } } #else static inline void set_pmd_early_shadow(pmd_t *pmd, pte_t *early_shadow) { pmd_populate_kernel(&init_mm, pmd, early_shadow); } #endif ... and move it to include/xen/xen-ops.h and call it with lm_alias(kasan_early_shadow_pte) as the second parameter. Juergen