From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from verein.lst.de ([213.95.11.211]:46885 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726544AbeIEXus (ORCPT ); Wed, 5 Sep 2018 19:50:48 -0400 Date: Wed, 5 Sep 2018 21:22:52 +0200 From: Christoph Hellwig To: Logan Gunthorpe Cc: Jason Gunthorpe , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org, Stephen Bates , Christoph Hellwig , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Max Gurtovoy , Dan Williams , =?iso-8859-1?B?Suly9G1l?= Glisse , Benjamin Herrenschmidt , Alex Williamson , Christian =?iso-8859-1?Q?K=F6nig?= Subject: Re: [PATCH v5 10/13] nvme-pci: Add support for P2P memory in requests Message-ID: <20180905192252.GA888@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-11-logang@deltatee.com> <20180904151638.GL335@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Tue, Sep 04, 2018 at 09:47:07AM -0600, Logan Gunthorpe wrote: > > > On 04/09/18 09:16 AM, Jason Gunthorpe wrote: > >> if (iod->nents) { > >> - dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > >> + /* P2PDMA requests do not need to be unmapped */ > >> + if (!is_pci_p2pdma_page(sg_page(iod->sg))) > >> + dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > > > > This seems like a poor direction, if we add IOMMU hairpin support we > > will need unmapping. > > It can always be added later. In any case, you'll have to convince > Christoph who requested the change; I'm not that invested in this decision. Yes, no point to add dead code here. In the long run we should aim for hiding the p2p address translation behind the normal DMA API anyway, but we're not quite ready for it yet. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id A2A982194D387 for ; Wed, 5 Sep 2018 12:19:15 -0700 (PDT) Date: Wed, 5 Sep 2018 21:22:52 +0200 From: Christoph Hellwig Subject: Re: [PATCH v5 10/13] nvme-pci: Add support for P2P memory in requests Message-ID: <20180905192252.GA888@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-11-logang@deltatee.com> <20180904151638.GL335@mellanox.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Logan Gunthorpe Cc: Alex Williamson , linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, =?iso-8859-1?B?Suly9G1l?= Glisse , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , Christoph Hellwig List-ID: On Tue, Sep 04, 2018 at 09:47:07AM -0600, Logan Gunthorpe wrote: > > > On 04/09/18 09:16 AM, Jason Gunthorpe wrote: > >> if (iod->nents) { > >> - dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > >> + /* P2PDMA requests do not need to be unmapped */ > >> + if (!is_pci_p2pdma_page(sg_page(iod->sg))) > >> + dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > > > > This seems like a poor direction, if we add IOMMU hairpin support we > > will need unmapping. > > It can always be added later. In any case, you'll have to convince > Christoph who requested the change; I'm not that invested in this decision. Yes, no point to add dead code here. In the long run we should aim for hiding the p2p address translation behind the normal DMA API anyway, but we're not quite ready for it yet. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@lst.de (Christoph Hellwig) Date: Wed, 5 Sep 2018 21:22:52 +0200 Subject: [PATCH v5 10/13] nvme-pci: Add support for P2P memory in requests In-Reply-To: References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-11-logang@deltatee.com> <20180904151638.GL335@mellanox.com> Message-ID: <20180905192252.GA888@lst.de> On Tue, Sep 04, 2018@09:47:07AM -0600, Logan Gunthorpe wrote: > > > On 04/09/18 09:16 AM, Jason Gunthorpe wrote: > >> if (iod->nents) { > >> - dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > >> + /* P2PDMA requests do not need to be unmapped */ > >> + if (!is_pci_p2pdma_page(sg_page(iod->sg))) > >> + dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > > > > This seems like a poor direction, if we add IOMMU hairpin support we > > will need unmapping. > > It can always be added later. In any case, you'll have to convince > Christoph who requested the change; I'm not that invested in this decision. Yes, no point to add dead code here. In the long run we should aim for hiding the p2p address translation behind the normal DMA API anyway, but we're not quite ready for it yet. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Date: Wed, 5 Sep 2018 21:22:52 +0200 From: Christoph Hellwig To: Logan Gunthorpe Subject: Re: [PATCH v5 10/13] nvme-pci: Add support for P2P memory in requests Message-ID: <20180905192252.GA888@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-11-logang@deltatee.com> <20180904151638.GL335@mellanox.com> MIME-Version: 1.0 In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch , Alex Williamson , Sagi Grimberg , linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Stephen Bates , linux-block@vger.kernel.org, =?iso-8859-1?B?Suly9G1l?= Glisse , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , Dan Williams , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+bjorn=helgaas.com@lists.infradead.org List-ID: On Tue, Sep 04, 2018 at 09:47:07AM -0600, Logan Gunthorpe wrote: > > > On 04/09/18 09:16 AM, Jason Gunthorpe wrote: > >> if (iod->nents) { > >> - dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > >> + /* P2PDMA requests do not need to be unmapped */ > >> + if (!is_pci_p2pdma_page(sg_page(iod->sg))) > >> + dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir); > > > > This seems like a poor direction, if we add IOMMU hairpin support we > > will need unmapping. > > It can always be added later. In any case, you'll have to convince > Christoph who requested the change; I'm not that invested in this decision. Yes, no point to add dead code here. In the long run we should aim for hiding the p2p address translation behind the normal DMA API anyway, but we're not quite ready for it yet. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme