vfio: Add PCI device driver

Add PCI device support for VFIO.  PCI devices expose regions
for accessing config space, I/O port space, and MMIO areas
of the device.  PCI config access is virtualized in the kernel,
allowing us to ensure the integrity of the system, by preventing
various accesses while reducing duplicate support across various
userspace drivers.  I/O port supports read/write access while
MMIO also supports mmap of sufficiently sized regions.  Support
for INTx, MSI, and MSI-X interrupts are provided using eventfds to
userspace.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index acb046f..0a4f180 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -223,6 +223,7 @@
 	__u32	argsz;
 	__u32	flags;
 #define VFIO_DEVICE_FLAGS_RESET	(1 << 0)	/* Device supports reset */
+#define VFIO_DEVICE_FLAGS_PCI	(1 << 1)	/* vfio-pci device */
 	__u32	num_regions;	/* Max region index + 1 */
 	__u32	num_irqs;	/* Max IRQ index + 1 */
 };
@@ -364,6 +365,31 @@
  */
 #define VFIO_DEVICE_RESET		_IO(VFIO_TYPE, VFIO_BASE + 11)
 
+/*
+ * The VFIO-PCI bus driver makes use of the following fixed region and
+ * IRQ index mapping.  Unimplemented regions return a size of zero.
+ * Unimplemented IRQ types return a count of zero.
+ */
+
+enum {
+	VFIO_PCI_BAR0_REGION_INDEX,
+	VFIO_PCI_BAR1_REGION_INDEX,
+	VFIO_PCI_BAR2_REGION_INDEX,
+	VFIO_PCI_BAR3_REGION_INDEX,
+	VFIO_PCI_BAR4_REGION_INDEX,
+	VFIO_PCI_BAR5_REGION_INDEX,
+	VFIO_PCI_ROM_REGION_INDEX,
+	VFIO_PCI_CONFIG_REGION_INDEX,
+	VFIO_PCI_NUM_REGIONS
+};
+
+enum {
+	VFIO_PCI_INTX_IRQ_INDEX,
+	VFIO_PCI_MSI_IRQ_INDEX,
+	VFIO_PCI_MSIX_IRQ_INDEX,
+	VFIO_PCI_NUM_IRQS
+};
+
 /* -------- API for Type1 VFIO IOMMU -------- */
 
 /**