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>,
"Martin Oliveira" <martin.oliveira@eideticom.com>,
"Chaitanya Kulkarni" <ckulkarnilinux@gmail.com>
Subject: Re: [PATCH v3 06/20] dma-direct: support PCI P2PDMA pages in dma-direct map_sg
Date: Tue, 28 Sep 2021 16:08:56 -0300 [thread overview]
Message-ID: <20210928190856.GN3544071@ziepe.ca> (raw)
In-Reply-To: <20210916234100.122368-7-logang@deltatee.com>
On Thu, Sep 16, 2021 at 05:40:46PM -0600, Logan Gunthorpe wrote:
> Add PCI P2PDMA support for dma_direct_map_sg() so that it can map
> PCI P2PDMA pages directly without a hack in the callers. This allows
> for heterogeneous SGLs that contain both P2PDMA and regular pages.
>
> A P2PDMA page may have three possible outcomes when being mapped:
> 1) If the data path between the two devices doesn't go through the
> root port, then it should be mapped with a PCI bus address
> 2) If the data path goes through the host bridge, it should be mapped
> normally, as though it were a CPU physical address
> 3) It is not possible for the two devices to communicate and thus
> the mapping operation should fail (and it will return -EREMOTEIO).
>
> SGL segments that contain PCI bus addresses are marked with
> sg_dma_mark_pci_p2pdma() and are ignored when unmapped.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> kernel/dma/direct.c | 44 ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 38 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 4c6c5e0635e3..fa8317e8ff44 100644
> +++ b/kernel/dma/direct.c
> @@ -13,6 +13,7 @@
> #include <linux/vmalloc.h>
> #include <linux/set_memory.h>
> #include <linux/slab.h>
> +#include <linux/pci-p2pdma.h>
> #include "direct.h"
>
> /*
> @@ -421,29 +422,60 @@ void dma_direct_sync_sg_for_cpu(struct device *dev,
> arch_sync_dma_for_cpu_all();
> }
>
> +/*
> + * Unmaps segments, except for ones marked as pci_p2pdma which do not
> + * require any further action as they contain a bus address.
> + */
> void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sgl,
> int nents, enum dma_data_direction dir, unsigned long attrs)
> {
> struct scatterlist *sg;
> int i;
>
> - for_each_sg(sgl, sg, nents, i)
> - dma_direct_unmap_page(dev, sg->dma_address, sg_dma_len(sg), dir,
> - attrs);
> + for_each_sg(sgl, sg, nents, i) {
> + if (sg_is_dma_pci_p2pdma(sg)) {
> + sg_dma_unmark_pci_p2pdma(sg);
> + } else {
> + dma_direct_unmap_page(dev, sg->dma_address,
> + sg_dma_len(sg), dir, attrs);
> + }
If the main usage of this SGL bit is to indicate if it has been DMA
mapped, or not, I think it should be renamed to something clearer.
p2pdma is being used for lots of things now, it feels very
counter-intuitive that P2PDMA pages are not flagged with
something called sg_is_dma_pci_p2pdma().
How about sg_is_dma_unmapped_address() ?
>
> for_each_sg(sgl, sg, nents, i) {
> + if (is_pci_p2pdma_page(sg_page(sg))) {
> + map = pci_p2pdma_map_segment(&p2pdma_state, dev, sg);
> + switch (map) {
> + case PCI_P2PDMA_MAP_BUS_ADDR:
> + continue;
> + case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> + /*
> + * Mapping through host bridge should be
> + * mapped normally, thus we do nothing
> + * and continue below.
> + */
> + break;
> + default:
> + ret = -EREMOTEIO;
> + goto out_unmap;
> + }
> + }
> +
> sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
> sg->offset, sg->length, dir, attrs);
dma_direct_map_page() can trigger swiotlb and I didn't see this series
dealing with that?
It would probably be fine for now to fail swiotlb_map() for p2p pages?
Jason
next prev parent reply other threads:[~2021-09-28 19:09 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 23:40 [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 01/20] lib/scatterlist: add flag for indicating P2PDMA segments in an SGL Logan Gunthorpe
2021-09-28 18:32 ` Jason Gunthorpe
2021-09-29 21:15 ` Logan Gunthorpe
2021-09-30 4:47 ` Chaitanya Kulkarni
2021-09-30 16:49 ` Logan Gunthorpe
2021-09-30 4:57 ` Chaitanya Kulkarni
2021-09-16 23:40 ` [PATCH v3 02/20] PCI/P2PDMA: attempt to set map_type if it has not been set Logan Gunthorpe
2021-09-27 18:50 ` Bjorn Helgaas
2021-09-16 23:40 ` [PATCH v3 03/20] PCI/P2PDMA: make pci_p2pdma_map_type() non-static Logan Gunthorpe
2021-09-27 18:46 ` Bjorn Helgaas
2021-09-28 18:48 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 04/20] PCI/P2PDMA: introduce helpers for dma_map_sg implementations Logan Gunthorpe
2021-09-27 18:53 ` Bjorn Helgaas
2021-09-27 19:59 ` Logan Gunthorpe
2021-09-28 18:55 ` Jason Gunthorpe
2021-09-29 21:26 ` Logan Gunthorpe
2021-09-28 22:05 ` [PATCH v3 4/20] " Jason Gunthorpe
2021-09-29 21:30 ` Logan Gunthorpe
2021-09-29 22:46 ` Jason Gunthorpe
2021-09-29 23:00 ` Logan Gunthorpe
2021-09-29 23:40 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 05/20] dma-mapping: allow EREMOTEIO return code for P2PDMA transfers Logan Gunthorpe
2021-09-28 18:57 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 06/20] dma-direct: support PCI P2PDMA pages in dma-direct map_sg Logan Gunthorpe
2021-09-28 19:08 ` Jason Gunthorpe [this message]
2021-09-16 23:40 ` [PATCH v3 07/20] dma-mapping: add flags to dma_map_ops to indicate PCI P2PDMA support Logan Gunthorpe
2021-09-28 19:11 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 08/20] iommu/dma: support PCI P2PDMA pages in dma-iommu map_sg Logan Gunthorpe
2021-09-28 19:15 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 09/20] nvme-pci: check DMA ops when indicating support for PCI P2PDMA Logan Gunthorpe
2021-09-30 5:06 ` Chaitanya Kulkarni
2021-09-30 16:51 ` Logan Gunthorpe
2021-09-30 17:19 ` Chaitanya Kulkarni
2021-09-16 23:40 ` [PATCH v3 10/20] nvme-pci: convert to using dma_map_sgtable() Logan Gunthorpe
2021-10-05 22:29 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 11/20] RDMA/core: introduce ib_dma_pci_p2p_dma_supported() Logan Gunthorpe
2021-09-28 19:17 ` Jason Gunthorpe
2021-10-05 22:31 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 12/20] RDMA/rw: use dma_map_sgtable() Logan Gunthorpe
2021-09-28 19:43 ` Jason Gunthorpe
2021-09-29 22:56 ` Logan Gunthorpe
2021-10-05 22:40 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 13/20] PCI/P2PDMA: remove pci_p2pdma_[un]map_sg() Logan Gunthorpe
2021-09-27 18:50 ` Bjorn Helgaas
2021-09-28 19:43 ` Jason Gunthorpe
2021-10-05 22:42 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 14/20] mm: introduce FOLL_PCI_P2PDMA to gate getting PCI P2PDMA pages Logan Gunthorpe
2021-09-28 19:47 ` Jason Gunthorpe
2021-09-29 21:34 ` Logan Gunthorpe
2021-09-29 22:48 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 15/20] iov_iter: introduce iov_iter_get_pages_[alloc_]flags() Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 16/20] block: set FOLL_PCI_P2PDMA in __bio_iov_iter_get_pages() Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 17/20] block: set FOLL_PCI_P2PDMA in bio_map_user_iov() Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 18/20] mm: use custom page_free for P2PDMA pages Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 19/20] PCI/P2PDMA: introduce pci_mmap_p2pmem() Logan Gunthorpe
2021-09-27 18:49 ` Bjorn Helgaas
2021-09-28 19:55 ` Jason Gunthorpe
2021-09-29 21:42 ` Logan Gunthorpe
2021-09-29 23:05 ` Jason Gunthorpe
2021-09-29 23:27 ` Logan Gunthorpe
2021-09-29 23:35 ` Jason Gunthorpe
2021-09-29 23:49 ` Logan Gunthorpe
2021-09-30 0:36 ` Jason Gunthorpe
2021-10-01 13:48 ` Jason Gunthorpe
2021-10-01 17:01 ` Logan Gunthorpe
2021-10-01 17:45 ` Jason Gunthorpe
2021-10-01 20:13 ` Logan Gunthorpe
2021-10-01 22:14 ` Jason Gunthorpe
2021-10-01 22:22 ` Logan Gunthorpe
2021-10-01 22:46 ` Jason Gunthorpe
2021-10-01 23:27 ` John Hubbard
2021-10-01 23:34 ` Logan Gunthorpe
2021-10-04 6:58 ` Christian König
2021-10-04 13:11 ` Jason Gunthorpe
2021-10-04 13:22 ` Christian König
2021-10-04 13:27 ` Jason Gunthorpe
2021-10-04 14:54 ` Christian König
2021-09-28 20:05 ` Jason Gunthorpe
2021-09-29 21:46 ` Logan Gunthorpe
2021-09-16 23:41 ` [PATCH v3 20/20] nvme-pci: allow mmaping the CMB in userspace Logan Gunthorpe
2021-09-28 20:02 ` [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices Jason Gunthorpe
2021-09-29 21:50 ` Logan Gunthorpe
2021-09-29 23:21 ` Jason Gunthorpe
2021-09-29 23:28 ` Logan Gunthorpe
2021-09-29 23:36 ` Jason Gunthorpe
2021-09-29 23:52 ` Logan Gunthorpe
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