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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 24740C55ABD for ; Fri, 6 Nov 2020 19:45:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABB8721556 for ; Fri, 6 Nov 2020 19:45:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b="EF51HxtZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728232AbgKFTpP (ORCPT ); Fri, 6 Nov 2020 14:45:15 -0500 Received: from ale.deltatee.com ([204.191.154.188]:60078 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727129AbgKFTpP (ORCPT ); Fri, 6 Nov 2020 14:45:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Sender: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=I/yMO/i0p9WTzMk8iTmPgQ7A1/uXaOZLwkcSaYry190=; b=EF51HxtZyF7eBA20tXsTF2DGDE IbfHm083EMnHxXpJYgIYTsp6r+mp9XWQb/XLgGWhtegx4w0IF1oPg6Iu83aOkKiOvCrjcBL1l6ogP F7p5WOzIjCQK9YLV8T/kmBmp579Gggn/M7dDLneVeKYVzdNnAWORs/zk7Cpponp8SJ0c/sAPS8uFI TdwpSPfkB9Yzi6zrO+pbtX5bsuoiEjd662srFEbfjGuxKPYx//X+W4l4VIpaOuVbk+3CZ+nG4mm4/ C62E/EDifK+3yt9mSInjQU4Klaw8r/WG0lHCbRHdZaOWog4xjJbhQXiRfVcbPEdFxo8Ld7uiMWlFr NGN7kz6Q==; Received: from s01060023bee90a7d.cg.shawcable.net ([24.64.145.4] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1kb7fV-00055w-HL; Fri, 06 Nov 2020 12:45:06 -0700 To: Jason Gunthorpe Cc: 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 , Christoph Hellwig , Dan Williams , =?UTF-8?Q?Christian_K=c3=b6nig?= , Ira Weiny , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter References: <20201106170036.18713-1-logang@deltatee.com> <20201106170036.18713-15-logang@deltatee.com> <20201106172206.GS36674@ziepe.ca> <20201106174223.GU36674@ziepe.ca> <2c2d2815-165e-2ef9-60d6-3ace7ff3aaa5@deltatee.com> <20201106180922.GV36674@ziepe.ca> <09885400-36f8-bc1d-27f0-a8adcf6104d4@deltatee.com> <20201106193024.GW36674@ziepe.ca> From: Logan Gunthorpe Message-ID: <03032637-0826-da76-aec2-121902b1c166@deltatee.com> Date: Fri, 6 Nov 2020 12:44:59 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201106193024.GW36674@ziepe.ca> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 24.64.145.4 X-SA-Exim-Rcpt-To: daniel.vetter@ffwll.ch, willy@infradead.org, ddutile@redhat.com, jhubbard@nvidia.com, iweiny@intel.com, christian.koenig@amd.com, dan.j.williams@intel.com, hch@lst.de, sbates@raithlin.com, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, jgg@ziepe.ca X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [RFC PATCH 14/15] PCI/P2PDMA: Introduce pci_mmap_p2pmem() X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-11-06 12:30 p.m., Jason Gunthorpe wrote: >> I certainly can't make decisions for code that isn't currently >> upstream. > > The rdma drivers are all upstream, what are you thinking about? Really? I feel like you should know what I mean here... I mean upstream code that actually uses the APIs that I'd have to introduce. I can't say here's an API feature that no code uses but the already upstream rdma driver might use eventually. It's fairly easy to send patches that make the necessary changes when someone adds a use of those changes inside the rdma code. >> Ultimately, if you aren't using the genpool you will have to implement >> your own mmap operation that somehow allocates the pages and your own >> page_free hook. > > Sure, the mlx5 driver already has a specialized alloctor for it's BAR > pages. So it *might* make sense to carve out a common helper to setup a VMA for P2PDMA to do the vm_flags check and set VM_MIXEDMAP... but besides that, there's no code that would be common to the two cases. >> I also don't expect this to be going upstream in the near term so don't >> get too excited about using it. > > I don't know, it is actually not that horrible, the GUP and IOMMU > related changes are simpler than I expected I think the deal breaker is the SGL hack and the fact that there are important IOMMU implementations that won't have support. Logan