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

+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

 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:

include/linux/vfio.h

@@ -98,7 +98,7 @@ extern void vfio_unregister_iommu_driver(
 
 /* Extensions */
 
-/* None yet */
+#define VFIO_TYPE1_IOMMU		1
 
 /*
  * The IOCTL interface is designed for extensibility by embedding the
@@ -364,4 +364,56 @@ struct vfio_irq_set {
  */
 #define VFIO_DEVICE_RESET		_IO(VFIO_TYPE, VFIO_BASE + 11)
 
+/* -------- API for Type1 VFIO IOMMU -------- */
+
+/**
+ * VFIO_IOMMU_GET_INFO - _IOR(VFIO_TYPE, VFIO_BASE + 12, struct vfio_iommu_info)
+ *
+ * Retrieve information about the IOMMU object. Fills in provided
+ * struct vfio_iommu_info. Caller sets argsz.
+ *
+ * XXX Should we do these by CHECK_EXTENSION too?
+ */
+struct vfio_iommu_type1_info {
+	__u32	argsz;
+	__u32	flags;
+#define VFIO_IOMMU_INFO_PGSIZES (1 << 0)	/* supported page sizes info */
+	__u64	iova_pgsizes;		/* Bitmap of supported page sizes */
+};
+
+#define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
+
+/**
+ * VFIO_IOMMU_MAP_DMA - _IOW(VFIO_TYPE, VFIO_BASE + 13, struct vfio_dma_map)
+ *
+ * Map process virtual addresses to IO virtual addresses using the
+ * provided struct vfio_dma_map. Caller sets argsz. READ &/ WRITE required.
+ */
+struct vfio_iommu_type1_dma_map {
+	__u32	argsz;
+	__u32	flags;
+#define VFIO_DMA_MAP_FLAG_READ (1 << 0)		/* readable from device */
+#define VFIO_DMA_MAP_FLAG_WRITE (1 << 1)	/* writable from device */
+	__u64	vaddr;				/* Process virtual address */
+	__u64	iova;				/* IO virtual address */
+	__u64	size;				/* Size of mapping (bytes) */
+};
+
+#define VFIO_IOMMU_MAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 13)
+
+/**
+ * VFIO_IOMMU_UNMAP_DMA - _IOW(VFIO_TYPE, VFIO_BASE + 14, struct vfio_dma_unmap)
+ *
+ * Unmap IO virtual addresses using the provided struct vfio_dma_unmap.
+ * Caller sets argsz.
+ */
+struct vfio_iommu_type1_dma_unmap {
+	__u32	argsz;
+	__u32	flags;
+	__u64	iova;				/* IO virtual address */
+	__u64	size;				/* Size of mapping (bytes) */
+};
+
+#define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)
+
 #endif /* VFIO_H */