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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Logan Gunthorpe <logang@deltatee.com>
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" <sbates@raithlin.com>,
	"Christoph Hellwig" <hch@lst.de>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Christian König" <christian.koenig@amd.com>,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Don Dutile" <ddutile@redhat.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Jakowski Andrzej" <andrzej.jakowski@intel.com>,
	"Minturn Dave B" <dave.b.minturn@intel.com>,
	"Jason Ekstrand" <jason@jlekstrand.net>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Xiong Jianxin" <jianxin.xiong@intel.com>,
	"Bjorn Helgaas" <helgaas@kernel.org>,
	"Ira Weiny" <ira.weiny@intel.com>,
	"Robin Murphy" <robin.murphy@arm.com>
Subject: Re: [PATCH 11/16] iommu/dma: Support PCI P2PDMA pages in dma-iommu map_sg
Date: Tue, 27 Apr 2021 16:43:37 -0300	[thread overview]
Message-ID: <20210427194337.GT2047089@ziepe.ca> (raw)
In-Reply-To: <20210408170123.8788-12-logang@deltatee.com>

On Thu, Apr 08, 2021 at 11:01:18AM -0600, Logan Gunthorpe wrote:
> When a PCI P2PDMA page is seen, set the IOVA length of the segment
> to zero so that it is not mapped into the IOVA. Then, in finalise_sg(),
> apply the appropriate bus address to the segment. The IOVA is not
> created if the scatterlist only consists of P2PDMA pages.

I expect P2P to work with systems that use ATS, so we'd want to see
those systems have the IOMMU programmed with the bus address.

Is it OK like this because the other logic prohibits all PCI cases
that would lean on the IOMMU, like ATS, hairpinning through the root
port, or transiting the root complex?

If yes, the code deserves a big comment explaining this is incomplete,
and I'd want to know we can finish this to include ATS at least based
on this series.

Jason

  reply	other threads:[~2021-04-27 19:43 UTC|newest]

Thread overview: 99+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-08 17:01 [PATCH 00/16] Add new DMA mapping operation for P2PDMA Logan Gunthorpe
2021-04-08 17:01 ` [PATCH 01/16] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn() Logan Gunthorpe
2021-05-02  3:58   ` John Hubbard
2021-05-03 15:57     ` Logan Gunthorpe
2021-05-03 18:17       ` John Hubbard
2021-05-03 18:20         ` Logan Gunthorpe
2021-05-03 18:23           ` John Hubbard
2021-05-03 18:24         ` Christoph Hellwig
2021-05-11 16:05     ` Don Dutile
2021-05-11 16:12       ` Logan Gunthorpe
2021-05-11 16:23         ` Don Dutile
2021-04-08 17:01 ` [PATCH 02/16] PCI/P2PDMA: Avoid pci_get_slot() which sleeps Logan Gunthorpe
2021-05-02  5:35   ` John Hubbard
2021-05-03 16:08     ` Logan Gunthorpe
2021-05-03 18:20       ` John Hubbard
2021-05-03 18:25       ` Christoph Hellwig
2021-05-11 16:05     ` Don Dutile
2021-05-11 16:16       ` Logan Gunthorpe
2021-05-11 16:05   ` Don Dutile
2021-05-11 16:14     ` Logan Gunthorpe
2021-04-08 17:01 ` [PATCH 03/16] PCI/P2PDMA: Attempt to set map_type if it has not been set Logan Gunthorpe
2021-05-02 19:58   ` John Hubbard
2021-05-03 16:17     ` Logan Gunthorpe
2021-05-03 18:22       ` John Hubbard
2021-05-03 18:35       ` Christoph Hellwig
2021-05-03 18:46         ` Logan Gunthorpe
2021-05-11 16:05     ` Don Dutile
2021-04-08 17:01 ` [PATCH 04/16] PCI/P2PDMA: Refactor pci_p2pdma_map_type() to take pagmap and device Logan Gunthorpe
2021-05-02 20:41   ` John Hubbard
2021-05-03 16:30     ` Logan Gunthorpe
2021-05-03 18:31       ` John Hubbard
2021-05-03 18:56         ` Logan Gunthorpe
2021-05-03 21:54           ` John Hubbard
2021-05-03 22:57             ` Jason Gunthorpe
2021-05-03 23:40               ` John Hubbard
2021-04-08 17:01 ` [PATCH 05/16] dma-mapping: Introduce dma_map_sg_p2pdma() Logan Gunthorpe
2021-04-27 19:22   ` Jason Gunthorpe
2021-04-27 22:49     ` Logan Gunthorpe
2021-04-27 19:31   ` Jason Gunthorpe
2021-04-27 22:55     ` Logan Gunthorpe
2021-04-27 23:01       ` Jason Gunthorpe
2021-05-03 18:28         ` Christoph Hellwig
2021-05-03 18:31           ` Logan Gunthorpe
2021-05-02 21:23   ` John Hubbard
2021-05-03 16:38     ` Logan Gunthorpe
2021-05-11 16:05   ` Don Dutile
2021-04-08 17:01 ` [PATCH 06/16] lib/scatterlist: Add flag for indicating P2PDMA segments in an SGL Logan Gunthorpe
2021-05-02 22:34   ` John Hubbard
2021-04-08 17:01 ` [PATCH 07/16] PCI/P2PDMA: Make pci_p2pdma_map_type() non-static Logan Gunthorpe
2021-05-02 22:44   ` John Hubbard
2021-05-03 16:39     ` Logan Gunthorpe
2021-05-11 16:06   ` Don Dutile
2021-05-11 16:17     ` Logan Gunthorpe
2021-04-08 17:01 ` [PATCH 08/16] PCI/P2PDMA: Introduce helpers for dma_map_sg implementations Logan Gunthorpe
2021-05-02 22:52   ` John Hubbard
2021-05-03  0:50   ` John Hubbard
2021-05-03 17:15     ` Logan Gunthorpe
2021-04-08 17:01 ` [PATCH 09/16] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg Logan Gunthorpe
2021-04-27 19:33   ` Jason Gunthorpe
2021-04-27 19:40     ` Jason Gunthorpe
2021-04-27 22:56       ` Logan Gunthorpe
2021-05-02 23:28   ` John Hubbard
2021-05-02 23:32     ` John Hubbard
2021-05-03 17:06       ` Logan Gunthorpe
2021-05-03 16:55     ` Logan Gunthorpe
2021-05-04  0:12       ` John Hubbard
2021-05-03 17:04     ` Logan Gunthorpe
2021-05-04  0:01       ` John Hubbard
2021-04-08 17:01 ` [PATCH 10/16] dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support Logan Gunthorpe
2021-05-03  0:32   ` John Hubbard
2021-05-03 17:09     ` Logan Gunthorpe
2021-05-11 16:06   ` Don Dutile
2021-05-11 16:19     ` Logan Gunthorpe
2021-04-08 17:01 ` [PATCH 11/16] iommu/dma: Support PCI P2PDMA pages in dma-iommu map_sg Logan Gunthorpe
2021-04-27 19:43   ` Jason Gunthorpe [this message]
2021-04-27 22:59     ` Logan Gunthorpe
2021-05-03  1:14   ` John Hubbard
2021-05-06 23:59     ` Logan Gunthorpe
2021-05-11 16:06   ` Don Dutile
2021-05-11 16:35     ` Logan Gunthorpe
2021-04-08 17:01 ` [PATCH 12/16] nvme-pci: Check DMA ops when indicating support for PCI P2PDMA Logan Gunthorpe
2021-05-03  1:29   ` John Hubbard
2021-05-03 17:17     ` Logan Gunthorpe
2021-05-04  0:17       ` John Hubbard
2021-04-08 17:01 ` [PATCH 13/16] nvme-pci: Convert to using dma_map_sg_p2pdma for p2pdma pages Logan Gunthorpe
2021-05-03  1:34   ` John Hubbard
2021-05-03 17:19     ` Logan Gunthorpe
2021-05-04  0:26       ` John Hubbard
2021-04-08 17:01 ` [PATCH 14/16] nvme-rdma: Ensure dma support when using p2pdma Logan Gunthorpe
2021-04-27 19:47   ` Jason Gunthorpe
2021-04-27 22:59     ` Logan Gunthorpe
2021-05-03  1:37   ` John Hubbard
2021-04-08 17:01 ` [PATCH 15/16] RDMA/rw: use dma_map_sg_p2pdma() Logan Gunthorpe
2021-04-08 17:01 ` [PATCH 16/16] PCI/P2PDMA: Remove pci_p2pdma_[un]map_sg() Logan Gunthorpe
2021-04-27 19:28 ` [PATCH 00/16] Add new DMA mapping operation for P2PDMA Jason Gunthorpe
2021-04-27 20:21   ` John Hubbard
2021-04-27 20:48     ` Dan Williams
2021-05-02  1:22 ` John Hubbard
2021-05-11 16:05 ` Don Dutile

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