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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DE78CCA479 for ; Fri, 17 Jun 2022 08:44:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1381094AbiFQIop (ORCPT ); Fri, 17 Jun 2022 04:44:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1381202AbiFQIoj (ORCPT ); Fri, 17 Jun 2022 04:44:39 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0F3F6972F; Fri, 17 Jun 2022 01:44:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=cRcPliFH8a5nYGYbcpuAxJdVHyV2ltCZ23v97rgf1A4=; b=KiuwHF6aDNvC5t/LWv3aUEPzwE KBgvUpfkf5qDI6GElmlPwqGlCsWtGNTsSld0WuZewPo0/4mkHtzAiWM6dEK1eY4RySKpAlhO65R1D WAwqSuEBlSHCf5DkNowUItxtdZkM4ZA/lqbf20XRt3tR3vQic1RG+gSiipHa082lrFeJntOO3nL6y th0tSkAnySXos78OuuOupQOTbIqiHOC5RM5RDCtt86BUATvPwCygEQGPiY1c2rMXDglxq26ZxUHjd msVefU68/GFcLY3Vs1Mt7LyDHUYqx6nUIuYz/IWEJAxO+kEDCvTyVrRF9ed8BsbP8AEHXp6NHAjQ4 s9lEnYkg==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1o27ag-006QLd-PI; Fri, 17 Jun 2022 08:44:30 +0000 Date: Fri, 17 Jun 2022 01:44:30 -0700 From: Christoph Hellwig To: Nicolin Chen Cc: kwankhede@nvidia.com, corbet@lwn.net, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, zhenyuw@linux.intel.com, zhi.a.wang@intel.com, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, tvrtko.ursulin@linux.intel.com, airlied@linux.ie, daniel@ffwll.ch, farman@linux.ibm.com, mjrosato@linux.ibm.com, pasic@linux.ibm.com, vneethv@linux.ibm.com, oberpar@linux.ibm.com, freude@linux.ibm.com, akrowiak@linux.ibm.com, jjherne@linux.ibm.com, alex.williamson@redhat.com, cohuck@redhat.com, jgg@nvidia.com, kevin.tian@intel.com, jchrist@linux.ibm.com, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: Re: [RFT][PATCH v1 5/6] vfio/ccw: Add kmap_local_page() for memcpy Message-ID: References: <20220616235212.15185-1-nicolinc@nvidia.com> <20220616235212.15185-6-nicolinc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220616235212.15185-6-nicolinc@nvidia.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Thu, Jun 16, 2022 at 04:52:11PM -0700, Nicolin Chen wrote: > The pinned PFN list returned from vfio_pin_pages() is simply converted > using page_to_pfn() without protection, so direct access via memcpy() > will crash on S390 if the PFN is an IO PFN. Instead, the pages should > be touched using kmap_local_page(). I don't see how this helps. kmap_local_page only works for either pages in the kernel direct map or highmem, but not for memory that needs to be ioremapped. And there is no highmem on s390.