Re: remove dma_virt_ops v2

From: Jason Gunthorpe <jgg@nvidia.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Bernard Metzler <bmt@zurich.ibm.com>,
	Zhu Yanjun <yanjunz@nvidia.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
	Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>,
	Santosh Shilimkar <santosh.shilimkar@oracle.com>,
	<linux-rdma@vger.kernel.org>, <rds-devel@oss.oracle.com>,
	<linux-pci@vger.kernel.org>, <iommu@lists.linux-foundation.org>
Subject: Re: remove dma_virt_ops v2
Date: Tue, 17 Nov 2020 15:41:29 -0400	[thread overview]
Message-ID: <20201117194129.GA1757698@nvidia.com> (raw)
In-Reply-To: <20201106181941.1878556-1-hch@lst.de>

On Fri, Nov 06, 2020 at 07:19:31PM +0100, Christoph Hellwig wrote:
> Hi Jason,
> 
> this series switches the RDMA core to opencode the special case of
> devices bypassing the DMA mapping in the RDMA ULPs.  The virt ops
> have caused a bit of trouble due to the P2P code node working with
> them due to the fact that we'd do two dma mapping iterations for a
> single I/O, but also are a bit of layering violation and lead to
> more code than necessary.
> 
> Tested with nvme-rdma over rxe.
> 
> Note that the rds changes are untested, as I could not find any
> simple rds test setup.
> 
> Changes since v2:
>  - simplify the INFINIBAND_VIRT_DMA dependencies
>  - add a ib_uses_virt_dma helper
>  - use ib_uses_virt_dma in nvmet-rdma to disable p2p for virt_dma devices
>  - use ib_dma_max_seg_size in umem
>  - stop using dmapool in rds
> 
> Changes since v1:
>  - disable software RDMA drivers for highmem configs
>  - update the PCI commit logs

All applied to for-next, thanks everyone

Jason