VFIO updates for v4.6-rc1

Various enablers for assignment of Intel graphics devices and future support of vGPU devices (Alex Williamson). This includes - Handling the vfio type1 interface as an API rather than a specific implementation, allowing multiple type1 providers. - Capability chains, similar to PCI device capabilities, that allow extending ioctls. Extensions here include device specific regions and sparse mmap descriptions. The former is used to expose non-PCI regions for IGD, including the OpRegion (particularly the Video BIOS Table), and read only PCI config access to the host and LPC bridge as drivers often depend on identifying those devices. Sparse mmaps here are used to describe the MSIx vector table, which vfio has always protected from mmap, but never had an API to explicitly define that protection. In future vGPU support this is expected to allow the description of PCI BARs that may mix direct access and emulated access within a single region. - The ability to expose the shadow ROM as an option ROM as IGD use cases may rely on the ROM even though the physical device does not make use of a PCI option ROM BAR. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (GNU/Linux) iQIcBAABAgAGBQJW6aT1AAoJECObm247sIsiiP4P/1xf7Z08/2QWVFQzex9CLcZk +/iJlyb/fTpPVQE+NTKPz3Qh5h6ZhSd/57s85IUqq0T6tgVPkoGx8kkyCjBaw2y1 yMezXZlQqJdZqGzQNI4OiHWvO+/vGxYKjQMfUnMlDM6dJgz4lGncGFoSouFPa3Vp mB12hGxrlk1cfIdb+C1KbfZcEdS0WhtigQtz8flBKgOfO+hYWmUO+CClJBhVw8Z4 RNcWNAxFfLuwUPVsPb6uOLG2g65SC2vmQ9k0Tnknf1znV3PFFVjITf0aM6uChLNP S3SgqtPX+6yOFyCuSEs8UKhhmCbeQmAyKgt5BpxV3Rw3OMP4PsVAehr82vQmSj6g 2o96pR2s8MDPBr8eG7gdRe4DQe3PonpLkpDfaghcpYqhkGEqNVeW5/GjiOzGQqD3 xMshzxJ1Iz7DOHkQRUVqOfupDB0TusJmTVKwvXe6yIYL9pjkUS/sbN9U563HYSES JTV68TMj0VKfKwD3XKYXvGH3km1sL4i5NMlAUrsDtsMkGlXEswoGbj82Mjc8+jUo BvWQTJb+kouJQ88VhsO2abg1UrO9E6u82iHFHy9fEObxE8KH7pvROlS93ihMT1Wv WQNuUcltdpHMRVX0BDknaPs3YtC3/TGgm3RcU5SZPbv/ys1471ZmJxMlAAKcfITr SuvkMTYElF5b1pigv46c =/lJn -----END PGP SIGNATURE----- Merge tag 'vfio-v4.6-rc1' of git://github.com/awilliam/linux-vfio Pull VFIO updates from Alex Williamson: "Various enablers for assignment of Intel graphics devices and future support of vGPU devices (Alex Williamson). This includes - Handling the vfio type1 interface as an API rather than a specific implementation, allowing multiple type1 providers. - Capability chains, similar to PCI device capabilities, that allow extending ioctls. Extensions here include device specific regions and sparse mmap descriptions. The former is used to expose non-PCI regions for IGD, including the OpRegion (particularly the Video BIOS Table), and read only PCI config access to the host and LPC bridge as drivers often depend on identifying those devices. Sparse mmaps here are used to describe the MSIx vector table, which vfio has always protected from mmap, but never had an API to explicitly define that protection. In future vGPU support this is expected to allow the description of PCI BARs that may mix direct access and emulated access within a single region. - The ability to expose the shadow ROM as an option ROM as IGD use cases may rely on the ROM even though the physical device does not make use of a PCI option ROM BAR" * tag 'vfio-v4.6-rc1' of git://github.com/awilliam/linux-vfio: vfio/pci: return -EFAULT if copy_to_user fails vfio/pci: Expose shadow ROM as PCI option ROM vfio/pci: Intel IGD host and LCP bridge config space access vfio/pci: Intel IGD OpRegion support vfio/pci: Enable virtual register in PCI config space vfio/pci: Add infrastructure for additional device specific regions vfio: Define device specific region type capability vfio/pci: Include sparse mmap capability for MSI-X table regions vfio: Define sparse mmap capability for regions vfio: Add capability chain helpers vfio: Define capability chains vfio: If an IOMMU backend fails, keep looking vfio/pci: Fix unsigned comparison overflow
2024-12-27 05:11:48 +00:00 · 2016-03-17 13:05:09 -07:00 · 2016-03-17 13:05:09 -07:00 · 45cb5230f8
commit 45cb5230f8
parent 3c0b8d1c5f c4aec31013
11 changed files with 706 additions and 37 deletions
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@ -26,3 +26,7 @@ config VFIO_PCI_MMAP
 config VFIO_PCI_INTX
 	depends on VFIO_PCI
 	def_bool y if !S390
+
+config VFIO_PCI_IGD
+	depends on VFIO_PCI
+	def_bool y if X86
--- a/drivers/vfio/pci/Makefile
+++ b/drivers/vfio/pci/Makefile
@ -1,4 +1,5 @@

 vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
+vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o

 obj-$(CONFIG_VFIO_PCI) += vfio-pci.o
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@ -111,6 +111,7 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
 }

 static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev);
+static void vfio_pci_disable(struct vfio_pci_device *vdev);

 static int vfio_pci_enable(struct vfio_pci_device *vdev)
 {
@ -169,13 +170,26 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
 	if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
 		vdev->has_vga = true;

+
+	if (vfio_pci_is_vga(pdev) &&
+	    pdev->vendor == PCI_VENDOR_ID_INTEL &&
+	    IS_ENABLED(CONFIG_VFIO_PCI_IGD)) {
+		ret = vfio_pci_igd_init(vdev);
+		if (ret) {
+			dev_warn(&vdev->pdev->dev,
+				 "Failed to setup Intel IGD regions\n");
+			vfio_pci_disable(vdev);
+			return ret;
+		}
+	}
+
 	return 0;
 }

 static void vfio_pci_disable(struct vfio_pci_device *vdev)
 {
 	struct pci_dev *pdev = vdev->pdev;
-	int bar;
+	int i, bar;

 	/* Stop the device from further DMA */
 	pci_clear_master(pdev);
@ -186,6 +200,13 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)

 	vdev->virq_disabled = false;

+	for (i = 0; i < vdev->num_regions; i++)
+		vdev->region[i].ops->release(vdev, &vdev->region[i]);
+
+	vdev->num_regions = 0;
+	kfree(vdev->region);
+	vdev->region = NULL; /* don't krealloc a freed pointer */
+
 	vfio_config_free(vdev);

 	for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) {
@ -421,6 +442,93 @@ static int vfio_pci_for_each_slot_or_bus(struct pci_dev *pdev,
 	return walk.ret;
 }

+static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
+				struct vfio_info_cap *caps)
+{
+	struct vfio_info_cap_header *header;
+	struct vfio_region_info_cap_sparse_mmap *sparse;
+	size_t end, size;
+	int nr_areas = 2, i = 0;
+
+	end = pci_resource_len(vdev->pdev, vdev->msix_bar);
+
+	/* If MSI-X table is aligned to the start or end, only one area */
+	if (((vdev->msix_offset & PAGE_MASK) == 0) ||
+	    (PAGE_ALIGN(vdev->msix_offset + vdev->msix_size) >= end))
+		nr_areas = 1;
+
+	size = sizeof(*sparse) + (nr_areas * sizeof(*sparse->areas));
+
+	header = vfio_info_cap_add(caps, size,
+				   VFIO_REGION_INFO_CAP_SPARSE_MMAP, 1);
+	if (IS_ERR(header))
+		return PTR_ERR(header);
+
+	sparse = container_of(header,
+			      struct vfio_region_info_cap_sparse_mmap, header);
+	sparse->nr_areas = nr_areas;
+
+	if (vdev->msix_offset & PAGE_MASK) {
+		sparse->areas[i].offset = 0;
+		sparse->areas[i].size = vdev->msix_offset & PAGE_MASK;
+		i++;
+	}
+
+	if (PAGE_ALIGN(vdev->msix_offset + vdev->msix_size) < end) {
+		sparse->areas[i].offset = PAGE_ALIGN(vdev->msix_offset +
+						     vdev->msix_size);
+		sparse->areas[i].size = end - sparse->areas[i].offset;
+		i++;
+	}
+
+	return 0;
+}
+
+static int region_type_cap(struct vfio_pci_device *vdev,
+			   struct vfio_info_cap *caps,
+			   unsigned int type, unsigned int subtype)
+{
+	struct vfio_info_cap_header *header;
+	struct vfio_region_info_cap_type *cap;
+
+	header = vfio_info_cap_add(caps, sizeof(*cap),
+				   VFIO_REGION_INFO_CAP_TYPE, 1);
+	if (IS_ERR(header))
+		return PTR_ERR(header);
+
+	cap = container_of(header, struct vfio_region_info_cap_type, header);
+	cap->type = type;
+	cap->subtype = subtype;
+
+	return 0;
+}
+
+int vfio_pci_register_dev_region(struct vfio_pci_device *vdev,
+				 unsigned int type, unsigned int subtype,
+				 const struct vfio_pci_regops *ops,
+				 size_t size, u32 flags, void *data)
+{
+	struct vfio_pci_region *region;
+
+	region = krealloc(vdev->region,
+			  (vdev->num_regions + 1) * sizeof(*region),
+			  GFP_KERNEL);
+	if (!region)
+		return -ENOMEM;
+
+	vdev->region = region;
+	vdev->region[vdev->num_regions].type = type;
+	vdev->region[vdev->num_regions].subtype = subtype;
+	vdev->region[vdev->num_regions].ops = ops;
+	vdev->region[vdev->num_regions].size = size;
+	vdev->region[vdev->num_regions].flags = flags;
+	vdev->region[vdev->num_regions].data = data;
+
+	vdev->num_regions++;
+
+	return 0;
+}
+
 static long vfio_pci_ioctl(void *device_data,
 			   unsigned int cmd, unsigned long arg)
 {
@ -443,7 +551,7 @@ static long vfio_pci_ioctl(void *device_data,
 		if (vdev->reset_works)
 			info.flags |= VFIO_DEVICE_FLAGS_RESET;

-		info.num_regions = VFIO_PCI_NUM_REGIONS;
+		info.num_regions = VFIO_PCI_NUM_REGIONS + vdev->num_regions;
 		info.num_irqs = VFIO_PCI_NUM_IRQS;

 		return copy_to_user((void __user *)arg, &info, minsz) ?
@ -452,6 +560,8 @@ static long vfio_pci_ioctl(void *device_data,
 	} else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
 		struct pci_dev *pdev = vdev->pdev;
 		struct vfio_region_info info;
+		struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
+		int i, ret;

 		minsz = offsetofend(struct vfio_region_info, offset);

@ -480,8 +590,15 @@ static long vfio_pci_ioctl(void *device_data,
 				     VFIO_REGION_INFO_FLAG_WRITE;
 			if (IS_ENABLED(CONFIG_VFIO_PCI_MMAP) &&
 			    pci_resource_flags(pdev, info.index) &
-			    IORESOURCE_MEM && info.size >= PAGE_SIZE)
+			    IORESOURCE_MEM && info.size >= PAGE_SIZE) {
 				info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
+				if (info.index == vdev->msix_bar) {
+					ret = msix_sparse_mmap_cap(vdev, &caps);
+					if (ret)
+						return ret;
+				}
+			}
+
 			break;
 		case VFIO_PCI_ROM_REGION_INDEX:
 		{
@ -493,8 +610,14 @@ static long vfio_pci_ioctl(void *device_data,

 			/* Report the BAR size, not the ROM size */
 			info.size = pci_resource_len(pdev, info.index);
-			if (!info.size)
-				break;
+			if (!info.size) {
+				/* Shadow ROMs appear as PCI option ROMs */
+				if (pdev->resource[PCI_ROM_RESOURCE].flags &
+							IORESOURCE_ROM_SHADOW)
+					info.size = 0x20000;
+				else
+					break;
+			}

 			/* Is it really there? */
 			io = pci_map_rom(pdev, &size);
@ -518,7 +641,40 @@ static long vfio_pci_ioctl(void *device_data,

 			break;
 		default:
-			return -EINVAL;
+			if (info.index >=
+			    VFIO_PCI_NUM_REGIONS + vdev->num_regions)
+				return -EINVAL;
+
+			i = info.index - VFIO_PCI_NUM_REGIONS;
+
+			info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
+			info.size = vdev->region[i].size;
+			info.flags = vdev->region[i].flags;
+
+			ret = region_type_cap(vdev, &caps,
+					      vdev->region[i].type,
+					      vdev->region[i].subtype);
+			if (ret)
+				return ret;
+		}
+
+		if (caps.size) {
+			info.flags |= VFIO_REGION_INFO_FLAG_CAPS;
+			if (info.argsz < sizeof(info) + caps.size) {
+				info.argsz = sizeof(info) + caps.size;
+				info.cap_offset = 0;
+			} else {
+				vfio_info_cap_shift(&caps, sizeof(info));
+				if (copy_to_user((void __user *)arg +
+						  sizeof(info), caps.buf,
+						  caps.size)) {
+					kfree(caps.buf);
+					return -EFAULT;
+				}
+				info.cap_offset = sizeof(info);
+			}
+
+			kfree(caps.buf);
 		}

 		return copy_to_user((void __user *)arg, &info, minsz) ?
@ -798,7 +954,7 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
 	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
 	struct vfio_pci_device *vdev = device_data;

-	if (index >= VFIO_PCI_NUM_REGIONS)
+	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
 		return -EINVAL;

 	switch (index) {
@ -815,6 +971,10 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,

 	case VFIO_PCI_VGA_REGION_INDEX:
 		return vfio_pci_vga_rw(vdev, buf, count, ppos, iswrite);
+	default:
+		index -= VFIO_PCI_NUM_REGIONS;
+		return vdev->region[index].ops->rw(vdev, buf,
+						   count, ppos, iswrite);
 	}

 	return -EINVAL;
@ -997,6 +1157,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)
 		return;

 	vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
+	kfree(vdev->region);
 	kfree(vdev);

 	if (vfio_pci_is_vga(pdev)) {
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@ -33,9 +33,8 @@

 #define PCI_CFG_SPACE_SIZE	256

-/* Useful "pseudo" capabilities */
+/* Fake capability ID for standard config space */
 #define PCI_CAP_ID_BASIC	0
-#define PCI_CAP_ID_INVALID	0xFF

 #define is_bar(offset)	\
 	((offset >= PCI_BASE_ADDRESS_0 && offset < PCI_BASE_ADDRESS_5 + 4) || \
@ -301,6 +300,23 @@ static int vfio_raw_config_read(struct vfio_pci_device *vdev, int pos,
 	return count;
 }

+/* Virt access uses only virtualization */
+static int vfio_virt_config_write(struct vfio_pci_device *vdev, int pos,
+				  int count, struct perm_bits *perm,
+				  int offset, __le32 val)
+{
+	memcpy(vdev->vconfig + pos, &val, count);
+	return count;
+}
+
+static int vfio_virt_config_read(struct vfio_pci_device *vdev, int pos,
+				 int count, struct perm_bits *perm,
+				 int offset, __le32 *val)
+{
+	memcpy(val, vdev->vconfig + pos, count);
+	return count;
+}
+
 /* Default capability regions to read-only, no-virtualization */
 static struct perm_bits cap_perms[PCI_CAP_ID_MAX + 1] = {
 	[0 ... PCI_CAP_ID_MAX] = { .readfn = vfio_direct_config_read }
@ -319,6 +335,11 @@ static struct perm_bits unassigned_perms = {
 	.writefn = vfio_raw_config_write
 };

+static struct perm_bits virt_perms = {
+	.readfn = vfio_virt_config_read,
+	.writefn = vfio_virt_config_write
+};
+
 static void free_perm_bits(struct perm_bits *perm)
 {
 	kfree(perm->virt);
@ -454,14 +475,19 @@ static void vfio_bar_fixup(struct vfio_pci_device *vdev)
 	bar = (__le32 *)&vdev->vconfig[PCI_ROM_ADDRESS];

 	/*
-	 * NB. we expose the actual BAR size here, regardless of whether
-	 * we can read it.  When we report the REGION_INFO for the ROM
-	 * we report what PCI tells us is the actual ROM size.
+	 * NB. REGION_INFO will have reported zero size if we weren't able
+	 * to read the ROM, but we still return the actual BAR size here if
+	 * it exists (or the shadow ROM space).
 	 */
 	if (pci_resource_start(pdev, PCI_ROM_RESOURCE)) {
 		mask = ~(pci_resource_len(pdev, PCI_ROM_RESOURCE) - 1);
 		mask |= PCI_ROM_ADDRESS_ENABLE;
 		*bar &= cpu_to_le32((u32)mask);
+	} else if (pdev->resource[PCI_ROM_RESOURCE].flags &
+					IORESOURCE_ROM_SHADOW) {
+		mask = ~(0x20000 - 1);
+		mask |= PCI_ROM_ADDRESS_ENABLE;
+		*bar &= cpu_to_le32((u32)mask);
 	} else
 		*bar = 0;

@ -1332,6 +1358,8 @@ static int vfio_cap_init(struct vfio_pci_device *vdev)
 				pos + i, map[pos + i], cap);
 		}

+		BUILD_BUG_ON(PCI_CAP_ID_MAX >= PCI_CAP_ID_INVALID_VIRT);
+
 		memset(map + pos, cap, len);
 		ret = vfio_fill_vconfig_bytes(vdev, pos, len);
 		if (ret)
@ -1419,9 +1447,9 @@ static int vfio_ecap_init(struct vfio_pci_device *vdev)
 		/*
 		 * Even though ecap is 2 bytes, we're currently a long way
 		 * from exceeding 1 byte capabilities.  If we ever make it
-		 * up to 0xFF we'll need to up this to a two-byte, byte map.
+		 * up to 0xFE we'll need to up this to a two-byte, byte map.
 		 */
-		BUILD_BUG_ON(PCI_EXT_CAP_ID_MAX >= PCI_CAP_ID_INVALID);
+		BUILD_BUG_ON(PCI_EXT_CAP_ID_MAX >= PCI_CAP_ID_INVALID_VIRT);

 		memset(map + epos, ecap, len);
 		ret = vfio_fill_vconfig_bytes(vdev, epos, len);
@ -1597,6 +1625,9 @@ static ssize_t vfio_config_do_rw(struct vfio_pci_device *vdev, char __user *buf,
 	if (cap_id == PCI_CAP_ID_INVALID) {
 		perm = &unassigned_perms;
 		cap_start = *ppos;
+	} else if (cap_id == PCI_CAP_ID_INVALID_VIRT) {
+		perm = &virt_perms;
+		cap_start = *ppos;
 	} else {
 		if (*ppos >= PCI_CFG_SPACE_SIZE) {
 			WARN_ON(cap_id > PCI_EXT_CAP_ID_MAX);
--- a/drivers/vfio/pci/vfio_pci_igd.c
+++ b/drivers/vfio/pci/vfio_pci_igd.c
@ -0,0 +1,280 @@
+/*
+ * VFIO PCI Intel Graphics support
+ *
+ * Copyright (C) 2016 Red Hat, Inc.  All rights reserved.
+ *	Author: Alex Williamson <alex.williamson@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Register a device specific region through which to provide read-only
+ * access to the Intel IGD opregion.  The register defining the opregion
+ * address is also virtualized to prevent user modification.
+ */
+
+#include <linux/io.h>
+#include <linux/pci.h>
+#include <linux/uaccess.h>
+#include <linux/vfio.h>
+
+#include "vfio_pci_private.h"
+
+#define OPREGION_SIGNATURE	"IntelGraphicsMem"
+#define OPREGION_SIZE		(8 * 1024)
+#define OPREGION_PCI_ADDR	0xfc
+
+static size_t vfio_pci_igd_rw(struct vfio_pci_device *vdev, char __user *buf,
+			      size_t count, loff_t *ppos, bool iswrite)
+{
+	unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
+	void *base = vdev->region[i].data;
+	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
+
+	if (pos >= vdev->region[i].size || iswrite)
+		return -EINVAL;
+
+	count = min(count, (size_t)(vdev->region[i].size - pos));
+
+	if (copy_to_user(buf, base + pos, count))
+		return -EFAULT;
+
+	*ppos += count;
+
+	return count;
+}
+
+static void vfio_pci_igd_release(struct vfio_pci_device *vdev,
+				 struct vfio_pci_region *region)
+{
+	memunmap(region->data);
+}
+
+static const struct vfio_pci_regops vfio_pci_igd_regops = {
+	.rw		= vfio_pci_igd_rw,
+	.release	= vfio_pci_igd_release,
+};
+
+static int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
+{
+	__le32 *dwordp = (__le32 *)(vdev->vconfig + OPREGION_PCI_ADDR);
+	u32 addr, size;
+	void *base;
+	int ret;
+
+	ret = pci_read_config_dword(vdev->pdev, OPREGION_PCI_ADDR, &addr);
+	if (ret)
+		return ret;
+
+	if (!addr || !(~addr))
+		return -ENODEV;
+
+	base = memremap(addr, OPREGION_SIZE, MEMREMAP_WB);
+	if (!base)
+		return -ENOMEM;
+
+	if (memcmp(base, OPREGION_SIGNATURE, 16)) {
+		memunmap(base);
+		return -EINVAL;
+	}
+
+	size = le32_to_cpu(*(__le32 *)(base + 16));
+	if (!size) {
+		memunmap(base);
+		return -EINVAL;
+	}
+
+	size *= 1024; /* In KB */
+
+	if (size != OPREGION_SIZE) {
+		memunmap(base);
+		base = memremap(addr, size, MEMREMAP_WB);
+		if (!base)
+			return -ENOMEM;
+	}
+
+	ret = vfio_pci_register_dev_region(vdev,
+		PCI_VENDOR_ID_INTEL | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
+		VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION,
+		&vfio_pci_igd_regops, size, VFIO_REGION_INFO_FLAG_READ, base);
+	if (ret) {
+		memunmap(base);
+		return ret;
+	}
+
+	/* Fill vconfig with the hw value and virtualize register */
+	*dwordp = cpu_to_le32(addr);
+	memset(vdev->pci_config_map + OPREGION_PCI_ADDR,
+	       PCI_CAP_ID_INVALID_VIRT, 4);
+
+	return ret;
+}
+
+static size_t vfio_pci_igd_cfg_rw(struct vfio_pci_device *vdev,
+				  char __user *buf, size_t count, loff_t *ppos,
+				  bool iswrite)
+{
+	unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
+	struct pci_dev *pdev = vdev->region[i].data;
+	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
+	size_t size;
+	int ret;
+
+	if (pos >= vdev->region[i].size || iswrite)
+		return -EINVAL;
+
+	size = count = min(count, (size_t)(vdev->region[i].size - pos));
+
+	if ((pos & 1) && size) {
+		u8 val;
+
+		ret = pci_user_read_config_byte(pdev, pos, &val);
+		if (ret)
+			return pcibios_err_to_errno(ret);
+
+		if (copy_to_user(buf + count - size, &val, 1))
+			return -EFAULT;
+
+		pos++;
+		size--;
+	}
+
+	if ((pos & 3) && size > 2) {
+		u16 val;
+
+		ret = pci_user_read_config_word(pdev, pos, &val);
+		if (ret)
+			return pcibios_err_to_errno(ret);
+
+		val = cpu_to_le16(val);
+		if (copy_to_user(buf + count - size, &val, 2))
+			return -EFAULT;
+
+		pos += 2;
+		size -= 2;
+	}
+
+	while (size > 3) {
+		u32 val;
+
+		ret = pci_user_read_config_dword(pdev, pos, &val);
+		if (ret)
+			return pcibios_err_to_errno(ret);
+
+		val = cpu_to_le32(val);
+		if (copy_to_user(buf + count - size, &val, 4))
+			return -EFAULT;
+
+		pos += 4;
+		size -= 4;
+	}
+
+	while (size >= 2) {
+		u16 val;
+
+		ret = pci_user_read_config_word(pdev, pos, &val);
+		if (ret)
+			return pcibios_err_to_errno(ret);
+
+		val = cpu_to_le16(val);
+		if (copy_to_user(buf + count - size, &val, 2))
+			return -EFAULT;
+
+		pos += 2;
+		size -= 2;
+	}
+
+	while (size) {
+		u8 val;
+
+		ret = pci_user_read_config_byte(pdev, pos, &val);
+		if (ret)
+			return pcibios_err_to_errno(ret);
+
+		if (copy_to_user(buf + count - size, &val, 1))
+			return -EFAULT;
+
+		pos++;
+		size--;
+	}
+
+	*ppos += count;
+
+	return count;
+}
+
+static void vfio_pci_igd_cfg_release(struct vfio_pci_device *vdev,
+				     struct vfio_pci_region *region)
+{
+	struct pci_dev *pdev = region->data;
+
+	pci_dev_put(pdev);
+}
+
+static const struct vfio_pci_regops vfio_pci_igd_cfg_regops = {
+	.rw		= vfio_pci_igd_cfg_rw,
+	.release	= vfio_pci_igd_cfg_release,
+};
+
+static int vfio_pci_igd_cfg_init(struct vfio_pci_device *vdev)
+{
+	struct pci_dev *host_bridge, *lpc_bridge;
+	int ret;
+
+	host_bridge = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0, 0));
+	if (!host_bridge)
+		return -ENODEV;
+
+	if (host_bridge->vendor != PCI_VENDOR_ID_INTEL ||
+	    host_bridge->class != (PCI_CLASS_BRIDGE_HOST << 8)) {
+		pci_dev_put(host_bridge);
+		return -EINVAL;
+	}
+
+	ret = vfio_pci_register_dev_region(vdev,
+		PCI_VENDOR_ID_INTEL | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
+		VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG,
+		&vfio_pci_igd_cfg_regops, host_bridge->cfg_size,
+		VFIO_REGION_INFO_FLAG_READ, host_bridge);
+	if (ret) {
+		pci_dev_put(host_bridge);
+		return ret;
+	}
+
+	lpc_bridge = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0x1f, 0));
+	if (!lpc_bridge)
+		return -ENODEV;
+
+	if (lpc_bridge->vendor != PCI_VENDOR_ID_INTEL ||
+	    lpc_bridge->class != (PCI_CLASS_BRIDGE_ISA << 8)) {
+		pci_dev_put(lpc_bridge);
+		return -EINVAL;
+	}
+
+	ret = vfio_pci_register_dev_region(vdev,
+		PCI_VENDOR_ID_INTEL | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
+		VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG,
+		&vfio_pci_igd_cfg_regops, lpc_bridge->cfg_size,
+		VFIO_REGION_INFO_FLAG_READ, lpc_bridge);
+	if (ret) {
+		pci_dev_put(lpc_bridge);
+		return ret;
+	}
+
+	return 0;
+}
+
+int vfio_pci_igd_init(struct vfio_pci_device *vdev)
+{
+	int ret;
+
+	ret = vfio_pci_igd_opregion_init(vdev);
+	if (ret)
+		return ret;
+
+	ret = vfio_pci_igd_cfg_init(vdev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@ -309,14 +309,14 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
 				      int vector, int fd, bool msix)
 {
 	struct pci_dev *pdev = vdev->pdev;
-	int irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
-	char *name = msix ? "vfio-msix" : "vfio-msi";
 	struct eventfd_ctx *trigger;
-	int ret;
+	int irq, ret;

-	if (vector >= vdev->num_ctx)
+	if (vector < 0 || vector >= vdev->num_ctx)
 		return -EINVAL;

+	irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
+
 	if (vdev->ctx[vector].trigger) {
 		free_irq(irq, vdev->ctx[vector].trigger);
 		irq_bypass_unregister_producer(&vdev->ctx[vector].producer);
@ -328,8 +328,9 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
 	if (fd < 0)
 		return 0;

-	vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "%s[%d](%s)",
-					   name, vector, pci_name(pdev));
+	vdev->ctx[vector].name = kasprintf(GFP_KERNEL, "vfio-msi%s[%d](%s)",
+					   msix ? "x" : "", vector,
+					   pci_name(pdev));
 	if (!vdev->ctx[vector].name)
 		return -ENOMEM;

@ -379,7 +380,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
 {
 	int i, j, ret = 0;

-	if (start + count > vdev->num_ctx)
+	if (start >= vdev->num_ctx || start + count > vdev->num_ctx)
 		return -EINVAL;

 	for (i = 0, j = start; i < count && !ret; i++, j++) {
@ -388,7 +389,7 @@ static int vfio_msi_set_block(struct vfio_pci_device *vdev, unsigned start,
 	}

 	if (ret) {
-		for (--j; j >= start; j--)
+		for (--j; j >= (int)start; j--)
 			vfio_msi_set_vector_signal(vdev, j, -1, msix);
 	}

--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@ -14,6 +14,7 @@
 #include <linux/mutex.h>
 #include <linux/pci.h>
 #include <linux/irqbypass.h>
+#include <linux/types.h>

 #ifndef VFIO_PCI_PRIVATE_H
 #define VFIO_PCI_PRIVATE_H
@ -24,6 +25,10 @@
 #define VFIO_PCI_INDEX_TO_OFFSET(index)	((u64)(index) << VFIO_PCI_OFFSET_SHIFT)
 #define VFIO_PCI_OFFSET_MASK	(((u64)(1) << VFIO_PCI_OFFSET_SHIFT) - 1)

+/* Special capability IDs predefined access */
+#define PCI_CAP_ID_INVALID		0xFF	/* default raw access */
+#define PCI_CAP_ID_INVALID_VIRT		0xFE	/* default virt access */
+
 struct vfio_pci_irq_ctx {
 	struct eventfd_ctx	*trigger;
 	struct virqfd		*unmask;
@ -33,6 +38,25 @@ struct vfio_pci_irq_ctx {
 	struct irq_bypass_producer	producer;
 };

+struct vfio_pci_device;
+struct vfio_pci_region;
+
+struct vfio_pci_regops {
+	size_t	(*rw)(struct vfio_pci_device *vdev, char __user *buf,
+		      size_t count, loff_t *ppos, bool iswrite);
+	void	(*release)(struct vfio_pci_device *vdev,
+			   struct vfio_pci_region *region);
+};
+
+struct vfio_pci_region {
+	u32				type;
+	u32				subtype;
+	const struct vfio_pci_regops	*ops;
+	void				*data;
+	size_t				size;
+	u32				flags;
+};
+
 struct vfio_pci_device {
 	struct pci_dev		*pdev;
 	void __iomem		*barmap[PCI_STD_RESOURCE_END + 1];
@ -45,6 +69,8 @@ struct vfio_pci_device {
 	struct vfio_pci_irq_ctx	*ctx;
 	int			num_ctx;
 	int			irq_type;
+	int			num_regions;
+	struct vfio_pci_region	*region;
 	u8			msi_qmax;
 	u8			msix_bar;
 	u16			msix_size;
@ -91,4 +117,17 @@ extern void vfio_pci_uninit_perm_bits(void);

 extern int vfio_config_init(struct vfio_pci_device *vdev);
 extern void vfio_config_free(struct vfio_pci_device *vdev);
+
+extern int vfio_pci_register_dev_region(struct vfio_pci_device *vdev,
+					unsigned int type, unsigned int subtype,
+					const struct vfio_pci_regops *ops,
+					size_t size, u32 flags, void *data);
+#ifdef CONFIG_VFIO_PCI_IGD
+extern int vfio_pci_igd_init(struct vfio_pci_device *vdev);
+#else
+static inline int vfio_pci_igd_init(struct vfio_pci_device *vdev)
+{
+	return -ENODEV;
+}
+#endif
 #endif /* VFIO_PCI_PRIVATE_H */
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@ -124,11 +124,14 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_device *vdev, char __user *buf,
 	void __iomem *io;
 	ssize_t done;

-	if (!pci_resource_start(pdev, bar))
+	if (pci_resource_start(pdev, bar))
+		end = pci_resource_len(pdev, bar);
+	else if (bar == PCI_ROM_RESOURCE &&
+		 pdev->resource[bar].flags & IORESOURCE_ROM_SHADOW)
+		end = 0x20000;
+	else
 		return -EINVAL;

-	end = pci_resource_len(pdev, bar);
-
 	if (pos >= end)
 		return -EINVAL;

--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@ -1080,30 +1080,26 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container,
 			continue;
 		}

-		/* module reference holds the driver we're working on */
-		mutex_unlock(&vfio.iommu_drivers_lock);
-
 		data = driver->ops->open(arg);
 		if (IS_ERR(data)) {
 			ret = PTR_ERR(data);
 			module_put(driver->ops->owner);
-			goto skip_drivers_unlock;
+			continue;
 		}

 		ret = __vfio_container_attach_groups(container, driver, data);
-		if (!ret) {
-			container->iommu_driver = driver;
-			container->iommu_data = data;
-		} else {
+		if (ret) {
 			driver->ops->release(data);
 			module_put(driver->ops->owner);
+			continue;
 		}

-		goto skip_drivers_unlock;
+		container->iommu_driver = driver;
+		container->iommu_data = data;
+		break;
 	}

 	mutex_unlock(&vfio.iommu_drivers_lock);
-skip_drivers_unlock:
 	up_write(&container->group_lock);

 	return ret;
@ -1732,6 +1728,60 @@ long vfio_external_check_extension(struct vfio_group *group, unsigned long arg)
 }
 EXPORT_SYMBOL_GPL(vfio_external_check_extension);

+/**
+ * Sub-module support
+ */
+/*
+ * Helper for managing a buffer of info chain capabilities, allocate or
+ * reallocate a buffer with additional @size, filling in @id and @version
+ * of the capability.  A pointer to the new capability is returned.
+ *
+ * NB. The chain is based at the head of the buffer, so new entries are
+ * added to the tail, vfio_info_cap_shift() should be called to fixup the
+ * next offsets prior to copying to the user buffer.
+ */
+struct vfio_info_cap_header *vfio_info_cap_add(struct vfio_info_cap *caps,
+					       size_t size, u16 id, u16 version)
+{
+	void *buf;
+	struct vfio_info_cap_header *header, *tmp;
+
+	buf = krealloc(caps->buf, caps->size + size, GFP_KERNEL);
+	if (!buf) {
+		kfree(caps->buf);
+		caps->size = 0;
+		return ERR_PTR(-ENOMEM);
+	}
+
+	caps->buf = buf;
+	header = buf + caps->size;
+
+	/* Eventually copied to user buffer, zero */
+	memset(header, 0, size);
+
+	header->id = id;
+	header->version = version;
+
+	/* Add to the end of the capability chain */
+	for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next)
+		; /* nothing */
+
+	tmp->next = caps->size;
+	caps->size += size;
+
+	return header;
+}
+EXPORT_SYMBOL_GPL(vfio_info_cap_add);
+
+void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset)
+{
+	struct vfio_info_cap_header *tmp;
+
+	for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next - offset)
+		tmp->next += offset;
+}
+EXPORT_SYMBOL_GPL(vfio_info_cap_shift);
+
 /**
 * Module/class support
 */
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@ -92,6 +92,17 @@ extern int vfio_external_user_iommu_id(struct vfio_group *group);
 extern long vfio_external_check_extension(struct vfio_group *group,
 					  unsigned long arg);

+/*
+ * Sub-module helpers
+ */
+struct vfio_info_cap {
+	struct vfio_info_cap_header *buf;
+	size_t size;
+};
+extern struct vfio_info_cap_header *vfio_info_cap_add(
+		struct vfio_info_cap *caps, size_t size, u16 id, u16 version);
+extern void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset);
+
 struct pci_dev;
 #ifdef CONFIG_EEH
 extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@ -59,6 +59,33 @@
 #define VFIO_TYPE	(';')
 #define VFIO_BASE	100

+/*
+ * For extension of INFO ioctls, VFIO makes use of a capability chain
+ * designed after PCI/e capabilities.  A flag bit indicates whether
+ * this capability chain is supported and a field defined in the fixed
+ * structure defines the offset of the first capability in the chain.
+ * This field is only valid when the corresponding bit in the flags
+ * bitmap is set.  This offset field is relative to the start of the
+ * INFO buffer, as is the next field within each capability header.
+ * The id within the header is a shared address space per INFO ioctl,
+ * while the version field is specific to the capability id.  The
+ * contents following the header are specific to the capability id.
+ */
+struct vfio_info_cap_header {
+	__u16	id;		/* Identifies capability */
+	__u16	version;	/* Version specific to the capability ID */
+	__u32	next;		/* Offset of next capability */
+};
+
+/*
+ * Callers of INFO ioctls passing insufficiently sized buffers will see
+ * the capability chain flag bit set, a zero value for the first capability
+ * offset (if available within the provided argsz), and argsz will be
+ * updated to report the necessary buffer size.  For compatibility, the
+ * INFO ioctl will not report error in this case, but the capability chain
+ * will not be available.
+ */
+
 /* -------- IOCTLs for VFIO file descriptor (/dev/vfio/vfio) -------- */

 /**
@ -194,13 +221,73 @@ struct vfio_region_info {
 #define VFIO_REGION_INFO_FLAG_READ	(1 << 0) /* Region supports read */
 #define VFIO_REGION_INFO_FLAG_WRITE	(1 << 1) /* Region supports write */
 #define VFIO_REGION_INFO_FLAG_MMAP	(1 << 2) /* Region supports mmap */
+#define VFIO_REGION_INFO_FLAG_CAPS	(1 << 3) /* Info supports caps */
 	__u32	index;		/* Region index */
-	__u32	resv;		/* Reserved for alignment */
+	__u32	cap_offset;	/* Offset within info struct of first cap */
 	__u64	size;		/* Region size (bytes) */
 	__u64	offset;		/* Region offset from start of device fd */
 };
 #define VFIO_DEVICE_GET_REGION_INFO	_IO(VFIO_TYPE, VFIO_BASE + 8)

+/*
+ * The sparse mmap capability allows finer granularity of specifying areas
+ * within a region with mmap support.  When specified, the user should only
+ * mmap the offset ranges specified by the areas array.  mmaps outside of the
+ * areas specified may fail (such as the range covering a PCI MSI-X table) or
+ * may result in improper device behavior.
+ *
+ * The structures below define version 1 of this capability.
+ */
+#define VFIO_REGION_INFO_CAP_SPARSE_MMAP	1
+
+struct vfio_region_sparse_mmap_area {
+	__u64	offset;	/* Offset of mmap'able area within region */
+	__u64	size;	/* Size of mmap'able area */
+};
+
+struct vfio_region_info_cap_sparse_mmap {
+	struct vfio_info_cap_header header;
+	__u32	nr_areas;
+	__u32	reserved;
+	struct vfio_region_sparse_mmap_area areas[];
+};
+
+/*
+ * The device specific type capability allows regions unique to a specific
+ * device or class of devices to be exposed.  This helps solve the problem for
+ * vfio bus drivers of defining which region indexes correspond to which region
+ * on the device, without needing to resort to static indexes, as done by
+ * vfio-pci.  For instance, if we were to go back in time, we might remove
+ * VFIO_PCI_VGA_REGION_INDEX and let vfio-pci simply define that all indexes
+ * greater than or equal to VFIO_PCI_NUM_REGIONS are device specific and we'd
+ * make a "VGA" device specific type to describe the VGA access space.  This
+ * means that non-VGA devices wouldn't need to waste this index, and thus the
+ * address space associated with it due to implementation of device file
+ * descriptor offsets in vfio-pci.
+ *
+ * The current implementation is now part of the user ABI, so we can't use this
+ * for VGA, but there are other upcoming use cases, such as opregions for Intel
+ * IGD devices and framebuffers for vGPU devices.  We missed VGA, but we'll
+ * use this for future additions.
+ *
+ * The structure below defines version 1 of this capability.
+ */
+#define VFIO_REGION_INFO_CAP_TYPE	2
+
+struct vfio_region_info_cap_type {
+	struct vfio_info_cap_header header;
+	__u32 type;	/* global per bus driver */
+	__u32 subtype;	/* type specific */
+};
+
+#define VFIO_REGION_TYPE_PCI_VENDOR_TYPE	(1 << 31)
+#define VFIO_REGION_TYPE_PCI_VENDOR_MASK	(0xffff)
+
+/* 8086 Vendor sub-types */
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION	(1)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG	(2)
+#define VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG	(3)
+
 /**
 * VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,
 *				    struct vfio_irq_info)
@ -336,7 +423,8 @@ enum {
 	 * between described ranges are unimplemented.
 	 */
 	VFIO_PCI_VGA_REGION_INDEX,
-	VFIO_PCI_NUM_REGIONS
+	VFIO_PCI_NUM_REGIONS = 9 /* Fixed user ABI, region indexes >=9 use */
+				 /* device specific cap to define content. */
 };

 enum {