From: Jason Gunthorpe <jgg@mellanox.com>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Jerome Glisse <jglisse@redhat.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rafael@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Christian Koenig <christian.koenig@amd.com>,
Felix Kuehling <Felix.Kuehling@amd.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>, Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <jroedel@suse.de>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>
Subject: Re: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma
Date: Wed, 30 Jan 2019 04:18:48 +0000 [thread overview]
Message-ID: <20190130041841.GB30598@mellanox.com> (raw)
In-Reply-To: <655a335c-ab91-d1fc-1ed3-b5f0d37c6226@deltatee.com>
On Tue, Jan 29, 2019 at 06:17:43PM -0700, Logan Gunthorpe wrote:
> This isn't answering my question at all... I specifically asked what is
> backing the VMA when we are *not* using HMM.
At least for RDMA what backs the VMA today is non-struct-page BAR
memory filled in with io_remap_pfn.
And we want to expose this for P2P DMA. None of the HMM stuff applies
here and the p2p_map/unmap are a nice simple approach that covers all
the needs RDMA has, at least.
Every attempt to give BAR memory to struct page has run into major
trouble, IMHO, so I like that this approach avoids that.
And if you don't have struct page then the only kernel object left to
hang meta data off is the VMA itself.
It seems very similar to the existing P2P work between in-kernel
consumers, just that VMA is now mediating a general user space driven
discovery process instead of being hard wired into a driver.
Jason
next prev parent reply other threads:[~2019-01-30 4:18 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-29 17:47 [RFC PATCH 0/5] Device peer to peer (p2p) through vma jglisse
2019-01-29 17:47 ` [RFC PATCH 1/5] pci/p2p: add a function to test peer to peer capability jglisse
2019-01-29 18:24 ` Logan Gunthorpe
2019-01-29 19:44 ` Greg Kroah-Hartman
2019-01-29 19:53 ` Jerome Glisse
2019-01-29 20:44 ` Logan Gunthorpe
2019-01-29 21:00 ` Jerome Glisse
2019-01-29 19:56 ` Alex Deucher
2019-01-29 20:00 ` Jerome Glisse
2019-01-29 20:24 ` Logan Gunthorpe
2019-01-29 21:28 ` Alex Deucher
2019-01-30 10:25 ` Christian König
2019-01-29 17:47 ` [RFC PATCH 2/5] drivers/base: " jglisse
2019-01-29 18:26 ` Logan Gunthorpe
2019-01-29 19:54 ` Jerome Glisse
2019-01-29 19:46 ` Greg Kroah-Hartman
2019-01-29 19:56 ` Jerome Glisse
2019-01-29 17:47 ` [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma jglisse
2019-01-29 18:36 ` Logan Gunthorpe
2019-01-29 19:11 ` Jerome Glisse
2019-01-29 19:24 ` Logan Gunthorpe
2019-01-29 19:44 ` Jerome Glisse
2019-01-29 20:43 ` Logan Gunthorpe
2019-01-30 7:52 ` Christoph Hellwig
2019-01-29 19:32 ` Jason Gunthorpe
2019-01-29 19:50 ` Jerome Glisse
2019-01-29 20:24 ` Jason Gunthorpe
2019-01-29 20:44 ` Jerome Glisse
2019-01-29 23:02 ` Jason Gunthorpe
2019-01-30 0:08 ` Jerome Glisse
2019-01-30 4:30 ` Jason Gunthorpe
2019-01-30 15:43 ` Jerome Glisse
2019-01-29 20:39 ` Logan Gunthorpe
2019-01-29 20:57 ` Jerome Glisse
2019-01-29 21:30 ` Logan Gunthorpe
2019-01-29 21:50 ` Jerome Glisse
2019-01-29 22:58 ` Logan Gunthorpe
2019-01-29 23:47 ` Jerome Glisse
2019-01-30 1:17 ` Logan Gunthorpe
2019-01-30 2:48 ` Jerome Glisse
2019-01-30 4:18 ` Jason Gunthorpe [this message]
2019-01-30 8:00 ` Christoph Hellwig
2019-01-30 15:49 ` Jerome Glisse
2019-01-30 19:06 ` Jason Gunthorpe
2019-01-30 19:45 ` Logan Gunthorpe
2019-01-30 19:59 ` Jason Gunthorpe
2019-01-30 21:01 ` Logan Gunthorpe
2019-01-30 21:50 ` Jason Gunthorpe
2019-01-30 22:52 ` Logan Gunthorpe
2019-01-30 23:30 ` Jason Gunthorpe
2019-01-31 8:13 ` Christoph Hellwig
2019-01-31 15:37 ` Jerome Glisse
2019-01-31 19:02 ` Jason Gunthorpe
2019-01-31 19:19 ` Logan Gunthorpe
2019-01-31 19:54 ` Jason Gunthorpe
2019-01-31 19:35 ` Jerome Glisse
2019-01-31 19:44 ` Logan Gunthorpe
2019-01-31 19:58 ` Jason Gunthorpe
2019-01-30 17:17 ` Logan Gunthorpe
2019-01-30 18:56 ` Jason Gunthorpe
2019-01-30 19:22 ` Jerome Glisse
2019-01-30 19:38 ` Jason Gunthorpe
2019-01-30 20:00 ` Logan Gunthorpe
2019-01-30 20:11 ` Jason Gunthorpe
2019-01-30 20:43 ` Jerome Glisse
2019-01-30 20:50 ` Jason Gunthorpe
2019-01-30 21:45 ` Jerome Glisse
2019-01-30 21:56 ` Jason Gunthorpe
2019-01-30 22:30 ` Jerome Glisse
2019-01-30 22:33 ` Jason Gunthorpe
2019-01-30 22:47 ` Jerome Glisse
2019-01-30 22:51 ` Jason Gunthorpe
2019-01-30 22:58 ` Jerome Glisse
2019-01-30 19:52 ` Logan Gunthorpe
2019-01-30 20:35 ` Jerome Glisse
2019-01-29 20:58 ` Jason Gunthorpe
2019-01-30 8:02 ` Christoph Hellwig
2019-01-30 10:33 ` Koenig, Christian
2019-01-30 15:55 ` Jerome Glisse
2019-01-30 17:26 ` Christoph Hellwig
2019-01-30 17:32 ` Logan Gunthorpe
2019-01-30 17:39 ` Jason Gunthorpe
2019-01-30 18:05 ` Jerome Glisse
2019-01-30 17:44 ` Jason Gunthorpe
2019-01-30 18:13 ` Logan Gunthorpe
2019-01-30 18:50 ` Jerome Glisse
2019-01-31 8:02 ` Christoph Hellwig
2019-01-31 15:03 ` Jerome Glisse
2019-01-30 19:19 ` Jason Gunthorpe
2019-01-30 19:48 ` Logan Gunthorpe
2019-01-30 20:44 ` Jason Gunthorpe
2019-01-31 8:05 ` Christoph Hellwig
2019-01-31 15:11 ` Jerome Glisse
2019-01-29 17:47 ` [RFC PATCH 4/5] mm/hmm: add support for peer to peer to HMM device memory jglisse
2019-01-29 17:47 ` [RFC PATCH 5/5] mm/hmm: add support for peer to peer to special device vma jglisse
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