Re: [PATCH 1/6] RMDA/sw: don't allow drivers using dma_virt_ops on highmem configs

From: Robin Murphy <robin.murphy@arm.com>
To: Christoph Hellwig <hch@lst.de>, Jason Gunthorpe <jgg@ziepe.ca>
Cc: Zhu Yanjun <yanjunz@nvidia.com>,
	Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
	linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org,
	Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>,
	iommu@lists.linux-foundation.org,
	Bjorn Helgaas <bhelgaas@google.com>,
	Bernard Metzler <bmt@zurich.ibm.com>,
	Logan Gunthorpe <logang@deltatee.com>
Subject: Re: [PATCH 1/6] RMDA/sw: don't allow drivers using dma_virt_ops on highmem configs
Date: Thu, 5 Nov 2020 12:15:46 +0000	[thread overview]
Message-ID: <40d0a990-0fca-6f12-16ff-3612a9847ab3@arm.com> (raw)
In-Reply-To: <20201105074205.1690638-2-hch@lst.de>

On 2020-11-05 07:42, Christoph Hellwig wrote:
> dma_virt_ops requires that all pages have a kernel virtual address.
> Introduce a INFINIBAND_VIRT_DMA Kconfig symbol that depends on !HIGHMEM
> and a large enough dma_addr_t, and make all three driver depend on the
> new symbol.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/infiniband/Kconfig           | 6 ++++++
>   drivers/infiniband/sw/rdmavt/Kconfig | 3 ++-
>   drivers/infiniband/sw/rxe/Kconfig    | 2 +-
>   drivers/infiniband/sw/siw/Kconfig    | 1 +
>   4 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/infiniband/Kconfig b/drivers/infiniband/Kconfig
> index 32a51432ec4f73..81acaf5fb5be67 100644
> --- a/drivers/infiniband/Kconfig
> +++ b/drivers/infiniband/Kconfig
> @@ -73,6 +73,12 @@ config INFINIBAND_ADDR_TRANS_CONFIGFS
>   	  This allows the user to config the default GID type that the CM
>   	  uses for each device, when initiaing new connections.
>   
> +config INFINIBAND_VIRT_DMA
> +	bool
> +	default y
> +	depends on !HIGHMEM
> +	depends on !64BIT || ARCH_DMA_ADDR_T_64BIT

Isn't that effectively always true now since 4965a68780c5? I had a quick 
try of manually overriding CONFIG_ARCH_DMA_ADDR_T_64BIT in my .config, 
and the build just forces it back to "=y".

Robin.

> +
>   if INFINIBAND_USER_ACCESS || !INFINIBAND_USER_ACCESS
>   source "drivers/infiniband/hw/mthca/Kconfig"
>   source "drivers/infiniband/hw/qib/Kconfig"
> diff --git a/drivers/infiniband/sw/rdmavt/Kconfig b/drivers/infiniband/sw/rdmavt/Kconfig
> index 9ef5f5ce1ff6b0..c8e268082952b0 100644
> --- a/drivers/infiniband/sw/rdmavt/Kconfig
> +++ b/drivers/infiniband/sw/rdmavt/Kconfig
> @@ -1,7 +1,8 @@
>   # SPDX-License-Identifier: GPL-2.0-only
>   config INFINIBAND_RDMAVT
>   	tristate "RDMA verbs transport library"
> -	depends on X86_64 && ARCH_DMA_ADDR_T_64BIT
> +	depends on INFINIBAND_VIRT_DMA
> +	depends on X86_64
>   	depends on PCI
>   	select DMA_VIRT_OPS
>   	help
> diff --git a/drivers/infiniband/sw/rxe/Kconfig b/drivers/infiniband/sw/rxe/Kconfig
> index a0c6c7dfc1814f..8810bfa680495a 100644
> --- a/drivers/infiniband/sw/rxe/Kconfig
> +++ b/drivers/infiniband/sw/rxe/Kconfig
> @@ -2,7 +2,7 @@
>   config RDMA_RXE
>   	tristate "Software RDMA over Ethernet (RoCE) driver"
>   	depends on INET && PCI && INFINIBAND
> -	depends on !64BIT || ARCH_DMA_ADDR_T_64BIT
> +	depends on INFINIBAND_VIRT_DMA
>   	select NET_UDP_TUNNEL
>   	select CRYPTO_CRC32
>   	select DMA_VIRT_OPS
> diff --git a/drivers/infiniband/sw/siw/Kconfig b/drivers/infiniband/sw/siw/Kconfig
> index b622fc62f2cd6d..3450ba5081df51 100644
> --- a/drivers/infiniband/sw/siw/Kconfig
> +++ b/drivers/infiniband/sw/siw/Kconfig
> @@ -1,6 +1,7 @@
>   config RDMA_SIW
>   	tristate "Software RDMA over TCP/IP (iWARP) driver"
>   	depends on INET && INFINIBAND && LIBCRC32C
> +	depends on INFINIBAND_VIRT_DMA
>   	select DMA_VIRT_OPS
>   	help
>   	This driver implements the iWARP RDMA transport over
> 
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