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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 6705FC2D0A3 for ; Mon, 9 Nov 2020 15:03:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BECA420897 for ; Mon, 9 Nov 2020 15:03:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="UtPuiqRO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BECA420897 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EE49D6B0036; Mon, 9 Nov 2020 10:03:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EC6E76B005C; Mon, 9 Nov 2020 10:03:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DF9856B005D; Mon, 9 Nov 2020 10:03:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0066.hostedemail.com [216.40.44.66]) by kanga.kvack.org (Postfix) with ESMTP id B2EF06B0036 for ; Mon, 9 Nov 2020 10:03:31 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 4DDAD1EE6 for ; Mon, 9 Nov 2020 15:03:31 +0000 (UTC) X-FDA: 77465198622.17.door28_081190b272ed Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 323A0180D0181 for ; Mon, 9 Nov 2020 15:03:31 +0000 (UTC) X-HE-Tag: door28_081190b272ed X-Filterd-Recvd-Size: 2698 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Mon, 9 Nov 2020 15:03:30 +0000 (UTC) Received: from dhcp-10-100-145-180.wdc.com (unknown [199.255.45.60]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3D39D2083B; Mon, 9 Nov 2020 15:03:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604934209; bh=r+Ft2tymmH5NpLInpLBcaHHGbXBmIxUIIoWZRRKi3Ns=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UtPuiqROcd/6G01mEcpCI4ZkuoLNoh/cHEoW1pWvWnXrcS9oX6qi25orcEe/HD6gQ /2y+a50beBfImRzQnG4uTWBnNextYf4nu2KfFLXSU6AOTbMFpSso49pl+Bj1AlzYpM TKyuOwfpDhx5CeUMmKig1ylwMR32SikIaTFabfbU= Date: Mon, 9 Nov 2020 07:03:26 -0800 From: Keith Busch To: Logan 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 , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Ira Weiny , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter Subject: Re: [RFC PATCH 15/15] nvme-pci: Allow mmaping the CMB in userspace Message-ID: <20201109150326.GA2221592@dhcp-10-100-145-180.wdc.com> References: <20201106170036.18713-1-logang@deltatee.com> <20201106170036.18713-16-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201106170036.18713-16-logang@deltatee.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Nov 06, 2020 at 10:00:36AM -0700, Logan Gunthorpe wrote: > Allow userspace to obtain CMB memory by mmaping the controller's > char device. The mmap call allocates and returns a hunk of CMB memory, > (the offset is ignored) so userspace does not have control over the > address within the CMB. > > A VMA allocated in this way will only be usable by drivers that set > FOLL_PCI_P2PDMA when calling GUP. And inter-device support will be > checked the first time the pages are mapped for DMA. > > Currently this is only supported by O_DIRECT to an PCI NVMe device > or through the NVMe passthrough IOCTL. Rather than make this be specific to nvme, could pci p2pdma create an mmap'able file for any resource registered with it?