diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index 5d5fc75..072fdac 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -273,9 +273,10 @@
 	return count;
 }
 
-static int vfio_direct_config_write(struct vfio_pci_device *vdev, int pos,
-				    int count, struct perm_bits *perm,
-				    int offset, __le32 val)
+/* Raw access skips any kind of virtualization */
+static int vfio_raw_config_write(struct vfio_pci_device *vdev, int pos,
+				 int count, struct perm_bits *perm,
+				 int offset, __le32 val)
 {
 	int ret;
 
@@ -286,13 +287,36 @@
 	return count;
 }
 
-/* Default all regions to read-only, no-virtualization */
+static int vfio_raw_config_read(struct vfio_pci_device *vdev, int pos,
+				int count, struct perm_bits *perm,
+				int offset, __le32 *val)
+{
+	int ret;
+
+	ret = vfio_user_config_read(vdev->pdev, pos, val, count);
+	if (ret)
+		return pcibios_err_to_errno(ret);
+
+	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 }
 };
 static struct perm_bits ecap_perms[PCI_EXT_CAP_ID_MAX + 1] = {
 	[0 ... PCI_EXT_CAP_ID_MAX] = { .readfn = vfio_direct_config_read }
 };
+/*
+ * Default unassigned regions to raw read-write access.  Some devices
+ * require this to function as they hide registers between the gaps in
+ * config space (be2net).  Like MMIO and I/O port registers, we have
+ * to trust the hardware isolation.
+ */
+static struct perm_bits unassigned_perms = {
+	.readfn = vfio_raw_config_read,
+	.writefn = vfio_raw_config_write
+};
 
 static void free_perm_bits(struct perm_bits *perm)
 {
@@ -778,16 +802,16 @@
 
 	/* Capabilities */
 	ret |= init_pci_cap_pm_perm(&cap_perms[PCI_CAP_ID_PM]);
-	cap_perms[PCI_CAP_ID_VPD].writefn = vfio_direct_config_write;
+	cap_perms[PCI_CAP_ID_VPD].writefn = vfio_raw_config_write;
 	ret |= init_pci_cap_pcix_perm(&cap_perms[PCI_CAP_ID_PCIX]);
-	cap_perms[PCI_CAP_ID_VNDR].writefn = vfio_direct_config_write;
+	cap_perms[PCI_CAP_ID_VNDR].writefn = vfio_raw_config_write;
 	ret |= init_pci_cap_exp_perm(&cap_perms[PCI_CAP_ID_EXP]);
 	ret |= init_pci_cap_af_perm(&cap_perms[PCI_CAP_ID_AF]);
 
 	/* Extended capabilities */
 	ret |= init_pci_ext_cap_err_perm(&ecap_perms[PCI_EXT_CAP_ID_ERR]);
 	ret |= init_pci_ext_cap_pwr_perm(&ecap_perms[PCI_EXT_CAP_ID_PWR]);
-	ecap_perms[PCI_EXT_CAP_ID_VNDR].writefn = vfio_direct_config_write;
+	ecap_perms[PCI_EXT_CAP_ID_VNDR].writefn = vfio_raw_config_write;
 
 	if (ret)
 		vfio_pci_uninit_perm_bits();
@@ -1495,35 +1519,25 @@
 	cap_id = vdev->pci_config_map[*ppos];
 
 	if (cap_id == PCI_CAP_ID_INVALID) {
-		if (iswrite)
-			return ret; /* drop */
-
-		/*
-		 * Per PCI spec 3.0, section 6.1, reads from reserved and
-		 * unimplemented registers return 0
-		 */
-		if (copy_to_user(buf, &val, count))
-			return -EFAULT;
-
-		return ret;
-	}
-
-	if (*ppos >= PCI_CFG_SPACE_SIZE) {
-		WARN_ON(cap_id > PCI_EXT_CAP_ID_MAX);
-
-		perm = &ecap_perms[cap_id];
-		cap_start = vfio_find_cap_start(vdev, *ppos);
-
+		perm = &unassigned_perms;
+		cap_start = *ppos;
 	} else {
-		WARN_ON(cap_id > PCI_CAP_ID_MAX);
+		if (*ppos >= PCI_CFG_SPACE_SIZE) {
+			WARN_ON(cap_id > PCI_EXT_CAP_ID_MAX);
 
-		perm = &cap_perms[cap_id];
-
-		if (cap_id == PCI_CAP_ID_MSI)
-			perm = vdev->msi_perm;
-
-		if (cap_id > PCI_CAP_ID_BASIC)
+			perm = &ecap_perms[cap_id];
 			cap_start = vfio_find_cap_start(vdev, *ppos);
+		} else {
+			WARN_ON(cap_id > PCI_CAP_ID_MAX);
+
+			perm = &cap_perms[cap_id];
+
+			if (cap_id == PCI_CAP_ID_MSI)
+				perm = vdev->msi_perm;
+
+			if (cap_id > PCI_CAP_ID_BASIC)
+				cap_start = vfio_find_cap_start(vdev, *ppos);
+		}
 	}
 
 	WARN_ON(!cap_start && cap_id != PCI_CAP_ID_BASIC);