From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Dan Williams <dan.j.williams@intel.com>,
Bjorn Helgaas <helgaas@kernel.org>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
"James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Jens Axboe <axboe@kernel.dk>,
Steve Wise <swise@opengridcomputing.com>,
Stephen Bates <sbates@raithlin.com>,
Max Gurtovoy <maxg@mellanox.com>,
Keith Busch <keith.busch@intel.com>,
linux-pci@vger.kernel.org,
linux-scsi <linux-scsi@vger.kernel.org>,
linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org,
linux-nvdimm <linux-nvdimm@ml01.01.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Jerome Glisse <jglisse@redhat.com>
Subject: Re: [RFC 0/8] Copy Offload with Peer-to-Peer PCI Memory
Date: Wed, 19 Apr 2017 11:14:51 -0600 [thread overview]
Message-ID: <20170419171451.GA10020@obsidianresearch.com> (raw)
In-Reply-To: <4899b011-bdfb-18d8-ef00-33a1516216a6@deltatee.com>
On Wed, Apr 19, 2017 at 10:48:51AM -0600, Logan Gunthorpe wrote:
> The pci_enable_p2p_bar function would then just need to call
> devm_memremap_pages with the dma_map callback set to a function that
> does the segment check and the offset calculation.
I don't see a use for the dma_map function pointer at this point..
It doesn't make alot of sense for the completor of the DMA to provide
a mapping op, the mapping process is *path* specific, not specific to
a completer/initiator.
So, I would suggest more like this:
static inline struct device *get_p2p_src(struct page *page)
{
struct device *res;
struct dev_pagemap *pgmap;
if (!is_zone_device_page(page))
return NULL;
pgmap = get_dev_pagemap(page_to_pfn(page), NULL);
if (!pgmap || pgmap->type != MEMORY_DEVICE_P2P)
/* For now ZONE_DEVICE memory that is not P2P is
assumed to be configured for DMA the same as CPU
memory. */
return ERR_PTR(-EINVAL);
res = pgmap->dev;
device_get(res);
put_dev_pagemap(pgmap);
return res;
}
dma_addr_t pci_p2p_same_segment(struct device *initator,
struct device *completer,
struct page *page)
{
if (! PCI initiator & completer)
return ERROR;
if (!same segment initiator & completer)
return ERROR;
// Translate page directly to the value programmed into the BAR
return (Completer's PCI BAR base address) + (offset of page within BAR);
}
// dma_sg_map
for (each sgl) {
struct page *page = sg_page(s);
struct device *p2p_src = get_p2p_src(page);
if (IS_ERR(p2p_src))
// fail dma_sg
if (p2p_src) {
bool needs_iommu = false;
pa = pci_p2p_same_segment(dev, p2p_src, page);
if (pa == ERROR)
pa = arch_p2p_cross_segment(dev, p2psrc, page, &needs_iommui);
device_put(p2p_src);
if (pa == ERROR)
// fail
if (!needs_iommu) {
// Insert PA directly into the result SGL
sg++;
continue;
}
}
else
// CPU memory
pa = page_to_phys(page);
To me it looks like the code duplication across the iommu stuff comes
from just duplicating the basic iommu algorithm in every driver.
To clean that up I think someone would need to hoist the overall sgl
loop and use more ops callbacks eg allocate_iommu_range,
assign_page_to_rage, dealloc_range, etc. This is a problem p2p makes
worse, but isn't directly causing :\
Jason
next prev parent reply other threads:[~2017-04-19 17:15 UTC|newest]
Thread overview: 105+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-16 15:44 [RFC 0/8] Copy Offload with Peer-to-Peer PCI Memory Dan Williams
2017-04-16 16:47 ` Logan Gunthorpe
2017-04-16 22:32 ` Benjamin Herrenschmidt
2017-04-17 5:13 ` Logan Gunthorpe
2017-04-17 7:20 ` Benjamin Herrenschmidt
2017-04-17 16:52 ` Logan Gunthorpe
2017-04-17 17:04 ` Dan Williams
2017-04-18 5:22 ` Logan Gunthorpe
2017-04-17 18:04 ` Jerome Glisse
2017-04-18 6:14 ` Logan Gunthorpe
2017-04-17 21:11 ` Benjamin Herrenschmidt
2017-04-18 5:43 ` Logan Gunthorpe
2017-04-18 6:29 ` Benjamin Herrenschmidt
2017-04-16 22:23 ` Benjamin Herrenschmidt
2017-04-18 16:45 ` Jason Gunthorpe
2017-04-18 17:27 ` Dan Williams
2017-04-18 18:00 ` Jason Gunthorpe
2017-04-18 18:34 ` Dan Williams
2017-04-19 1:13 ` Benjamin Herrenschmidt
2017-04-18 22:46 ` Benjamin Herrenschmidt
2017-04-18 22:52 ` Dan Williams
2017-04-18 18:30 ` Logan Gunthorpe
2017-04-18 19:01 ` Jason Gunthorpe
2017-04-18 19:35 ` Logan Gunthorpe
2017-04-18 19:48 ` Dan Williams
2017-04-18 20:29 ` Jerome Glisse
2017-04-18 20:31 ` Dan Williams
2017-04-18 20:48 ` Logan Gunthorpe
2017-04-19 1:17 ` Benjamin Herrenschmidt
2017-04-18 21:03 ` Jason Gunthorpe
2017-04-18 21:11 ` Dan Williams
2017-04-18 21:22 ` Jason Gunthorpe
2017-04-18 21:36 ` Dan Williams
2017-04-18 22:15 ` Logan Gunthorpe
2017-04-18 22:28 ` Dan Williams
2017-04-18 22:42 ` Jason Gunthorpe
2017-04-18 22:51 ` Dan Williams
2017-04-18 23:21 ` Jason Gunthorpe
2017-04-19 1:25 ` Benjamin Herrenschmidt
2017-04-18 22:48 ` Logan Gunthorpe
2017-04-18 22:50 ` Dan Williams
2017-04-18 22:56 ` Logan Gunthorpe
2017-04-18 23:02 ` Dan Williams
2017-04-19 1:21 ` Benjamin Herrenschmidt
2017-04-18 21:31 ` Logan Gunthorpe
2017-04-18 22:24 ` Jason Gunthorpe
2017-04-18 23:03 ` Logan Gunthorpe
2017-04-19 1:23 ` Benjamin Herrenschmidt
2017-04-19 1:20 ` Benjamin Herrenschmidt
2017-04-19 15:55 ` Jason Gunthorpe
2017-04-19 16:48 ` Logan Gunthorpe
2017-04-19 17:01 ` Dan Williams
2017-04-19 17:32 ` Jerome Glisse
2017-04-19 17:41 ` Dan Williams
2017-04-19 18:11 ` Logan Gunthorpe
2017-04-19 18:19 ` Logan Gunthorpe
2017-04-19 18:30 ` Dan Williams
2017-04-19 18:41 ` Logan Gunthorpe
2017-04-19 18:44 ` Dan Williams
2017-04-20 20:43 ` Stephen Bates
2017-04-20 20:47 ` Dan Williams
2017-04-20 23:07 ` Stephen Bates
2017-04-21 4:59 ` Dan Williams
2017-04-19 17:14 ` Jason Gunthorpe [this message]
2017-04-19 18:01 ` Logan Gunthorpe
2017-04-19 18:32 ` Jason Gunthorpe
2017-04-19 19:02 ` Logan Gunthorpe
2017-04-19 19:31 ` Jason Gunthorpe
2017-04-19 19:41 ` Logan Gunthorpe
2017-04-19 20:48 ` Jason Gunthorpe
2017-04-19 22:55 ` Logan Gunthorpe
2017-04-20 0:07 ` Dan Williams
2017-04-18 19:48 ` Jason Gunthorpe
2017-04-18 20:06 ` Logan Gunthorpe
-- strict thread matches above, loose matches on Subject: below --
2017-03-30 22:12 Logan Gunthorpe
2017-04-12 5:22 ` Benjamin Herrenschmidt
2017-04-12 17:09 ` Logan Gunthorpe
2017-04-12 21:55 ` Benjamin Herrenschmidt
2017-04-13 21:22 ` Logan Gunthorpe
2017-04-13 22:37 ` Benjamin Herrenschmidt
2017-04-13 23:26 ` Bjorn Helgaas
2017-04-14 4:16 ` Jason Gunthorpe
2017-04-14 4:40 ` Logan Gunthorpe
2017-04-14 11:37 ` Benjamin Herrenschmidt
2017-04-14 11:39 ` Benjamin Herrenschmidt
2017-04-14 11:37 ` Benjamin Herrenschmidt
2017-04-14 17:30 ` Logan Gunthorpe
2017-04-14 19:04 ` Bjorn Helgaas
2017-04-14 22:07 ` Benjamin Herrenschmidt
2017-04-15 17:41 ` Logan Gunthorpe
2017-04-15 22:09 ` Dan Williams
2017-04-16 3:01 ` Benjamin Herrenschmidt
2017-04-16 4:46 ` Logan Gunthorpe
2017-04-16 15:53 ` Dan Williams
2017-04-16 16:34 ` Logan Gunthorpe
2017-04-16 22:31 ` Benjamin Herrenschmidt
2017-04-24 7:36 ` Knut Omang
2017-04-24 16:14 ` Logan Gunthorpe
2017-04-25 6:30 ` Knut Omang
2017-04-25 17:03 ` Logan Gunthorpe
2017-04-25 21:23 ` Stephen Bates
2017-04-25 21:23 ` Stephen Bates
2017-04-16 22:26 ` Benjamin Herrenschmidt
2017-04-15 22:17 ` Benjamin Herrenschmidt
2017-04-16 5:36 ` Logan Gunthorpe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170419171451.GA10020@obsidianresearch.com \
--to=jgunthorpe@obsidianresearch.com \
--cc=axboe@kernel.dk \
--cc=benh@kernel.crashing.org \
--cc=dan.j.williams@intel.com \
--cc=hch@lst.de \
--cc=helgaas@kernel.org \
--cc=jejb@linux.vnet.ibm.com \
--cc=jglisse@redhat.com \
--cc=keith.busch@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvdimm@ml01.01.org \
--cc=linux-nvme@lists.infradead.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-rdma@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=logang@deltatee.com \
--cc=martin.petersen@oracle.com \
--cc=maxg@mellanox.com \
--cc=sagi@grimberg.me \
--cc=sbates@raithlin.com \
--cc=swise@opengridcomputing.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).