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 B4DF6C43334 for ; Sun, 19 Jun 2022 06:18:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234112AbiFSGSc (ORCPT ); Sun, 19 Jun 2022 02:18:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45866 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231810AbiFSGS3 (ORCPT ); Sun, 19 Jun 2022 02:18:29 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4874BA444; Sat, 18 Jun 2022 23:18:26 -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=j/JBNwa/VyqAIaEnsFXpkXodHo6vqnGAI1xYD1tiqZo=; b=jLy3lF1kmifcevO6HwuwLb2bFh cICoOWdEb52iimiuzsyFdgSGbDfBBC787zRztZfYBUzRkU3DbiisicNQha2BbgsLDASZAqlpbDqX+ CayphOqce8z+TfP2HkVcrHrm2hHTIy8TWjnWp29vlBJQCVPNbRwYvTisXiVrym+4d8fsSzlTNF8jG 7w53PIyh2fuPAL/nVK5V2AB0RS2rivSUMvoExuxG5X4NfK3QTjdT3ES8S5RwQ+x+hewyZrG6fZzsL FfoWD4w/eycsn6U0AMNoWXmZphF8mWTSvbeuLBmDvLOr81ZFwgR3gAHlhSrhrZyPWZinA3hRHEMd4 Eklp6K+Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1o2oGH-00DL70-A1; Sun, 19 Jun 2022 06:18:17 +0000 Date: Sat, 18 Jun 2022 23:18:17 -0700 From: Christoph Hellwig To: Nicolin Chen Cc: Christoph Hellwig , 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 6/6] vfio: Replace phys_pfn with phys_page for vfio_pin_pages() Message-ID: References: <20220616235212.15185-1-nicolinc@nvidia.com> <20220616235212.15185-7-nicolinc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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-kernel@vger.kernel.org On Fri, Jun 17, 2022 at 03:06:25PM -0700, Nicolin Chen wrote: > On Fri, Jun 17, 2022 at 01:54:05AM -0700, Christoph Hellwig wrote: > > There is a bunch of code an comments in the iommu type1 code that > > suggest we can pin memory that is not page backed. > > Would you mind explaining the use case for pinning memory that > isn't page backed? And do we have such use case so far? Sorry, I should have deleted that sentence. I wrote it before spending some more time to dig through the code and all the locked memory has page backing. There just seem to be a lot of checks left inbetween if a pfn is page backed, mostly due to the pfn based calling convetions. > I can do that. I tried once, but there were just too much changes > inside type1 code that felt like a chain reaction. If we plan to > eventually replace with IOMMUFD implementations, these changes in > type1 might not be necessary, I thought. To make sure we keep full compatibility I suspect the final iommufd implementation has to be gradutally created from the existing code anyway. 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 87169CCA480 for ; Sun, 19 Jun 2022 06:18:32 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9EC9310FC29; Sun, 19 Jun 2022 06:18:31 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by gabe.freedesktop.org (Postfix) with ESMTPS id 87C5310FB92; Sun, 19 Jun 2022 06:18:30 +0000 (UTC) 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=j/JBNwa/VyqAIaEnsFXpkXodHo6vqnGAI1xYD1tiqZo=; b=jLy3lF1kmifcevO6HwuwLb2bFh cICoOWdEb52iimiuzsyFdgSGbDfBBC787zRztZfYBUzRkU3DbiisicNQha2BbgsLDASZAqlpbDqX+ CayphOqce8z+TfP2HkVcrHrm2hHTIy8TWjnWp29vlBJQCVPNbRwYvTisXiVrym+4d8fsSzlTNF8jG 7w53PIyh2fuPAL/nVK5V2AB0RS2rivSUMvoExuxG5X4NfK3QTjdT3ES8S5RwQ+x+hewyZrG6fZzsL FfoWD4w/eycsn6U0AMNoWXmZphF8mWTSvbeuLBmDvLOr81ZFwgR3gAHlhSrhrZyPWZinA3hRHEMd4 Eklp6K+Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1o2oGH-00DL70-A1; Sun, 19 Jun 2022 06:18:17 +0000 Date: Sat, 18 Jun 2022 23:18:17 -0700 From: Christoph Hellwig To: Nicolin Chen Message-ID: References: <20220616235212.15185-1-nicolinc@nvidia.com> <20220616235212.15185-7-nicolinc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Subject: Re: [Intel-gfx] [RFT][PATCH v1 6/6] vfio: Replace phys_pfn with phys_page for vfio_pin_pages() X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mjrosato@linux.ibm.com, linux-doc@vger.kernel.org, airlied@linux.ie, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kwankhede@nvidia.com, vneethv@linux.ibm.com, agordeev@linux.ibm.com, pasic@linux.ibm.com, kvm@vger.kernel.org, corbet@lwn.net, Christoph Hellwig , jgg@nvidia.com, borntraeger@linux.ibm.com, intel-gfx@lists.freedesktop.org, jjherne@linux.ibm.com, farman@linux.ibm.com, jchrist@linux.ibm.com, gor@linux.ibm.com, linux-s390@vger.kernel.org, hca@linux.ibm.com, freude@linux.ibm.com, rodrigo.vivi@intel.com, intel-gvt-dev@lists.freedesktop.org, akrowiak@linux.ibm.com, cohuck@redhat.com, oberpar@linux.ibm.com, svens@linux.ibm.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, Jun 17, 2022 at 03:06:25PM -0700, Nicolin Chen wrote: > On Fri, Jun 17, 2022 at 01:54:05AM -0700, Christoph Hellwig wrote: > > There is a bunch of code an comments in the iommu type1 code that > > suggest we can pin memory that is not page backed. > > Would you mind explaining the use case for pinning memory that > isn't page backed? And do we have such use case so far? Sorry, I should have deleted that sentence. I wrote it before spending some more time to dig through the code and all the locked memory has page backing. There just seem to be a lot of checks left inbetween if a pfn is page backed, mostly due to the pfn based calling convetions. > I can do that. I tried once, but there were just too much changes > inside type1 code that felt like a chain reaction. If we plan to > eventually replace with IOMMUFD implementations, these changes in > type1 might not be necessary, I thought. To make sure we keep full compatibility I suspect the final iommufd implementation has to be gradutally created from the existing code anyway.