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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 37A2AC43334 for ; Tue, 5 Jul 2022 17:42:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ZZ183XwVsELBVPB7JnEyzJPWbbXM+pLVSpBuXVG55QQ=; b=dzCosIgFt308TjKtSzBMRZvsHD w6zjWPXwOXmM9uz4jf5USQRxjru87zo+Ut/gSoUdbNMX4wP6CzuHqd6UKs6NXR+6uzzVLK2Qa6Wmz t11Hx2pOJ193NQGipyA8NAnqPeZWltghT3ZqNCJygIqy1393hFeZyTWhiQT4q2lvV3UrvEaWGqvD0 yPbmHkUgl5gXUtXA7xwz9LDGCqYbq4wVLD6EYhgJiB2pQxfRpkt4rlqehDaA66vEyxTvbvqhERoTC hsSaVh0+TXV8XXW48CFsSK6MRFSd45uGiVkP6WEp+NDZgqhS5WoxHgMaKW73RRNjgxhxjtMxdGGhh Y5wkwadw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o8mZP-001wnL-8A; Tue, 05 Jul 2022 17:42:43 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o8mZL-001wkb-NF for linux-nvme@lists.infradead.org; Tue, 05 Jul 2022 17:42:42 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 01C0361876; Tue, 5 Jul 2022 17:42:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4620C341C7; Tue, 5 Jul 2022 17:42:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657042955; bh=18T9JrVrQmGUhIeB/JuQTrGy9yUM/iGt2yUQiwv239s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=E+wsESQzjBq0Jm7GRcNunkZNg/B9u9pWxluE8Hvyw5c8ngmjtRMeYZplVgH18CEMg +CWBPqMRpf6vtqHc8uVHP4AxL8xobnRkwM4XtCynMLc+/O8b28/frnTwxcKPJt8aG2 gLkaIa6aOTwyOr/X8xpnr7Wu6h8BVukKTtB9ibvU= Date: Tue, 5 Jul 2022 19:42:32 +0200 From: Greg Kroah-Hartman To: Logan Gunthorpe Cc: Christoph Hellwig , Jason Gunthorpe , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Dan Williams , Christian =?iso-8859-1?Q?K=F6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell , Bjorn Helgaas Subject: Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem() Message-ID: References: <20220629175906.GU23621@ziepe.ca> <20220705075108.GB17451@lst.de> <20220705135102.GE23621@ziepe.ca> <20220705161240.GB13721@lst.de> <20220705164315.GB14484@lst.de> <20220705165039.GB14566@lst.de> <1bd43ef7-0403-bd25-087c-d54d5af677e4@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1bd43ef7-0403-bd25-087c-d54d5af677e4@deltatee.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220705_104239_902083_0188FE74 X-CRM114-Status: GOOD ( 27.25 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, Jul 05, 2022 at 11:32:23AM -0600, Logan Gunthorpe wrote: > > > On 2022-07-05 11:21, Greg Kroah-Hartman wrote: > > On Tue, Jul 05, 2022 at 06:50:39PM +0200, Christoph Hellwig wrote: > >> [note for the newcomers, this is about allowing mmap()ing the PCIe > >> P2P memory from the generic PCI P2P code through sysfs, and more > >> importantly how to revoke it on device removal] > > > > We allow mmap on PCIe config space today, right? Why is this different > > from what pci_create_legacy_files() does today? > > > >> On Tue, Jul 05, 2022 at 10:44:49AM -0600, Logan Gunthorpe wrote: > >>> We might be able to. I'm not sure. I'll have to figure out how to find > >>> that inode from the p2pdma code. I haven't found an obvious interface to > >>> do that. > >> > >> I think the right way to approach this would be a new sysfs API > >> that internally calls unmap_mapping_range internally instead of > >> exposing the inode. I suspect that might actually be the right thing > >> to do for iomem_inode as well. > > > > Why do we need something new and how is this any different from the PCI > > binary files I mention above? We have supported PCI hotplug for a very > > long time, do the current PCI binary sysfs files not work properly with > > mmap and removing a device? > > The P2PDMA code allocates and hands out struct pages to userspace that > are backed with ZONE_DEVICE memory from a device's BAR. This is quite > different from the existing binary files mentioned above which neither > support struct pages nor allocation. Why would you want to do this through a sysfs interface? that feels horrid...