From: Logan Gunthorpe <logang@deltatee.com>
To: Keith Busch <kbusch@kernel.org>
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>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Christian König" <christian.koenig@amd.com>,
"Ira Weiny" <iweiny@intel.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Don Dutile" <ddutile@redhat.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>
Subject: Re: [RFC PATCH 15/15] nvme-pci: Allow mmaping the CMB in userspace
Date: Mon, 9 Nov 2020 09:50:00 -0700 [thread overview]
Message-ID: <e718b81f-9cb8-dfe8-b1a6-ebb79f302732@deltatee.com> (raw)
In-Reply-To: <20201109150326.GA2221592@dhcp-10-100-145-180.wdc.com>
On 2020-11-09 8:03 a.m., Keith Busch wrote:
> On Fri, Nov 06, 2020 at 10:00:36AM -0700, Logan Gunthorpe wrote:
>> Allow userspace to obtain CMB memory by mmaping the controller's
>> char device. The mmap call allocates and returns a hunk of CMB memory,
>> (the offset is ignored) so userspace does not have control over the
>> address within the CMB.
>>
>> A VMA allocated in this way will only be usable by drivers that set
>> FOLL_PCI_P2PDMA when calling GUP. And inter-device support will be
>> checked the first time the pages are mapped for DMA.
>>
>> Currently this is only supported by O_DIRECT to an PCI NVMe device
>> or through the NVMe passthrough IOCTL.
>
> Rather than make this be specific to nvme, could pci p2pdma create an
> mmap'able file for any resource registered with it?
It's certainly possible. However, other people have been arguing that
more of this should be specific to NVMe as some use cases do not want to
use the genalloc inside p2pdma.
Logan
prev parent reply other threads:[~2020-11-09 16:50 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 17:00 [RFC PATCH 00/15] Userspace P2PDMA with O_DIRECT NVMe devices Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 01/15] PCI/P2PDMA: Don't sleep in upstream_bridge_distance_warn() Logan Gunthorpe
2020-11-09 9:12 ` Christoph Hellwig
2020-11-06 17:00 ` [RFC PATCH 02/15] PCI/P2PDMA: Attempt to set map_type if it has not been set Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 03/15] PCI/P2PDMA: Introduce pci_p2pdma_should_map_bus() and pci_p2pdma_bus_offset() Logan Gunthorpe
2020-11-10 23:25 ` Bjorn Helgaas
2020-11-10 23:42 ` Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 04/15] lib/scatterlist: Add flag for indicating P2PDMA segments in an SGL Logan Gunthorpe
2020-11-09 9:12 ` Christoph Hellwig
2020-11-09 14:02 ` Robin Murphy
2020-11-09 16:47 ` Logan Gunthorpe
2020-12-10 1:22 ` Dan Williams
2020-12-10 2:06 ` Logan Gunthorpe
2020-12-10 4:04 ` Dan Williams
2020-12-10 16:44 ` Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 05/15] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 06/15] dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 07/15] iommu/dma: Support PCI P2PDMA pages in dma-iommu map_sg Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 08/15] nvme-pci: Check DMA ops when indicating support for PCI P2PDMA Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 09/15] nvme-pci: Convert to using dma_map_sg for p2pdma pages Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 10/15] mm: Introduce FOLL_PCI_P2PDMA to gate getting PCI P2PDMA pages Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 11/15] iov_iter: Introduce iov_iter_get_pages_[alloc_]flags() Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 12/15] block: Set FOLL_PCI_P2PDMA in __bio_iov_iter_get_pages() Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 13/15] block: Set FOLL_PCI_P2PDMA in bio_map_user_iov() Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 14/15] PCI/P2PDMA: Introduce pci_mmap_p2pmem() Logan Gunthorpe
2020-11-06 17:22 ` Jason Gunthorpe
2020-11-06 17:28 ` Logan Gunthorpe
2020-11-06 17:42 ` Jason Gunthorpe
2020-11-06 17:53 ` Logan Gunthorpe
2020-11-06 18:09 ` Jason Gunthorpe
2020-11-06 18:20 ` Logan Gunthorpe
2020-11-06 19:30 ` Jason Gunthorpe
2020-11-06 19:44 ` Logan Gunthorpe
2020-11-06 19:53 ` Jason Gunthorpe
2020-11-06 20:03 ` Logan Gunthorpe
2020-11-07 0:14 ` Jason Gunthorpe
2020-11-07 2:50 ` Logan Gunthorpe
2020-11-06 17:00 ` [RFC PATCH 15/15] nvme-pci: Allow mmaping the CMB in userspace Logan Gunthorpe
2020-11-06 17:39 ` Jason Gunthorpe
2020-11-06 17:43 ` Logan Gunthorpe
2020-11-09 15:03 ` Keith Busch
2020-11-09 16:50 ` Logan Gunthorpe [this message]
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