vfio: Type1 IOMMU implementation

This VFIO IOMMU backend is designed primarily for AMD-Vi and Intel
VT-d hardware, but is potentially usable by anything supporting
similar mapping functionality.  We arbitrarily call this a Type1
backend for lack of a better name.  This backend has no IOVA
or host memory mapping restrictions for the user and is optimized
for relatively static mappings.  Mapped areas are pinned into system
memory.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/Kconfig

@@ -1,6 +1,12 @@
+config VFIO_IOMMU_TYPE1
+	tristate
+	depends on VFIO
+	default n
+
 menuconfig VFIO
 	tristate "VFIO Non-Privileged userspace driver framework"
 	depends on IOMMU_API
+	select VFIO_IOMMU_TYPE1 if X86
 	help
 	  VFIO provides a framework for secure userspace device drivers.
 	  See Documentation/vfio.txt for more details.

drivers/vfio/Makefile

@@ -1 +1,3 @@
 obj-$(CONFIG_VFIO) += vfio.o
+obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
+obj-$(CONFIG_VFIO_PCI) += pci/

drivers/vfio/vfio.c

@@ -1376,6 +1376,13 @@ static int __init vfio_init(void)
 
 	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
 
+	/*
+	 * Attempt to load known iommu-drivers.  This gives us a working
+	 * environment without the user needing to explicitly load iommu
+	 * drivers.
+	 */
+	request_module_nowait("vfio_iommu_type1");
+
 	return 0;
 
 err_groups_cdev: