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Tue, 5 Jul 2022 17:42:37 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 517918133A Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by smtp1.osuosl.org (Postfix) with ESMTPS id 517918133A for ; Tue, 5 Jul 2022 17:42:37 +0000 (UTC) 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 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-Disposition: inline In-Reply-To: <1bd43ef7-0403-bd25-087c-d54d5af677e4@deltatee.com> Cc: linux-pci@vger.kernel.org, Dave Hansen , linux-nvme@lists.infradead.org, Stephen Bates , linux-mm@kvack.org, Jason Ekstrand , Ira Weiny , Christoph Hellwig , Minturn Dave B , Martin Oliveira , Matthew Wilcox , Jason Gunthorpe , Chaitanya Kulkarni , Bjorn Helgaas , Daniel Vetter , Ralph Campbell , John Hubbard , linux-block@vger.kernel.org, Bjorn Helgaas , Dan Williams , Xiong Jianxin , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Robin Murphy , Christian =?iso-8859-1?Q?K=F6nig?= X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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... _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu