RMDA/sw: Don't allow drivers using dma_virt_ops on highmem configs

dma_virt_ops requires that all pages have a kernel virtual address.
Introduce a INFINIBAND_VIRT_DMA Kconfig symbol that depends on !HIGHMEM
and make all three drivers depend on the new symbol.

Also remove the ARCH_DMA_ADDR_T_64BIT dependency, which has been obsolete
since commit 4965a68780 ("arch: define the ARCH_DMA_ADDR_T_64BIT config
symbol in lib/Kconfig")

Fixes: 551199aca1 ("lib/dma-virt: Add dma_virt_ops")
Link: https://lore.kernel.org/r/20201106181941.1878556-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/Kconfig

@@ -73,6 +73,9 @@ 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
+	def_bool !HIGHMEM
+
 if INFINIBAND_USER_ACCESS || !INFINIBAND_USER_ACCESS
 source "drivers/infiniband/hw/mthca/Kconfig"
 source "drivers/infiniband/hw/qib/Kconfig"

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

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

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