3 files changed, 87 insertions, 23 deletions

diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index affa34745be9..ffd0632c3cbc 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -1012,6 +1012,7 @@ static int vfio_vc_cap_len(struct vfio_pci_device *vdev, u16 pos)
 static int vfio_cap_len(struct vfio_pci_device *vdev, u8 cap, u8 pos)
 {
 	struct pci_dev *pdev = vdev->pdev;
+	u32 dword;
 	u16 word;
 	u8 byte;
 	int ret;
@@ -1025,7 +1026,9 @@ static int vfio_cap_len(struct vfio_pci_device *vdev, u8 cap, u8 pos)
 			return pcibios_err_to_errno(ret);
 
 		if (PCI_X_CMD_VERSION(word)) {
-			vdev->extended_caps = true;
+			/* Test for extended capabilities */
+			pci_read_config_dword(pdev, PCI_CFG_SPACE_SIZE, &dword);
+			vdev->extended_caps = (dword != 0);
 			return PCI_CAP_PCIX_SIZEOF_V2;
 		} else
 			return PCI_CAP_PCIX_SIZEOF_V0;
@@ -1037,9 +1040,11 @@ static int vfio_cap_len(struct vfio_pci_device *vdev, u8 cap, u8 pos)
 
 		return byte;
 	case PCI_CAP_ID_EXP:
-		/* length based on version */
-		vdev->extended_caps = true;
+		/* Test for extended capabilities */
+		pci_read_config_dword(pdev, PCI_CFG_SPACE_SIZE, &dword);
+		vdev->extended_caps = (dword != 0);
 
+		/* length based on version */
 		if ((pcie_caps_reg(pdev) & PCI_EXP_FLAGS_VERS) == 1)
 			return PCI_CAP_EXP_ENDPOINT_SIZEOF_V1;
 		else
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 4bc704e1b7c7..641bc87bdb96 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -130,8 +130,8 @@ static int virqfd_enable(struct vfio_pci_device *vdev,
 			 void (*thread)(struct vfio_pci_device *, void *),
 			 void *data, struct virqfd **pvirqfd, int fd)
 {
-	struct file *file = NULL;
-	struct eventfd_ctx *ctx = NULL;
+	struct fd irqfd;
+	struct eventfd_ctx *ctx;
 	struct virqfd *virqfd;
 	int ret = 0;
 	unsigned int events;
@@ -149,16 +149,16 @@ static int virqfd_enable(struct vfio_pci_device *vdev,
 	INIT_WORK(&virqfd->shutdown, virqfd_shutdown);
 	INIT_WORK(&virqfd->inject, virqfd_inject);
 
-	file = eventfd_fget(fd);
-	if (IS_ERR(file)) {
-		ret = PTR_ERR(file);
-		goto fail;
+	irqfd = fdget(fd);
+	if (!irqfd.file) {
+		ret = -EBADF;
+		goto err_fd;
 	}
 
-	ctx = eventfd_ctx_fileget(file);
+	ctx = eventfd_ctx_fileget(irqfd.file);
 	if (IS_ERR(ctx)) {
 		ret = PTR_ERR(ctx);
-		goto fail;
+		goto err_ctx;
 	}
 
 	virqfd->eventfd = ctx;
@@ -174,7 +174,7 @@ static int virqfd_enable(struct vfio_pci_device *vdev,
 	if (*pvirqfd) {
 		spin_unlock_irq(&vdev->irqlock);
 		ret = -EBUSY;
-		goto fail;
+		goto err_busy;
 	}
 	*pvirqfd = virqfd;
 
@@ -187,7 +187,7 @@ static int virqfd_enable(struct vfio_pci_device *vdev,
 	init_waitqueue_func_entry(&virqfd->wait, virqfd_wakeup);
 	init_poll_funcptr(&virqfd->pt, virqfd_ptable_queue_proc);
 
-	events = file->f_op->poll(file, &virqfd->pt);
+	events = irqfd.file->f_op->poll(irqfd.file, &virqfd->pt);
 
 	/*
 	 * Check if there was an event already pending on the eventfd
@@ -202,17 +202,14 @@ static int virqfd_enable(struct vfio_pci_device *vdev,
 	 * Do not drop the file until the irqfd is fully initialized,
 	 * otherwise we might race against the POLLHUP.
 	 */
-	fput(file);
+	fdput(irqfd);
 
 	return 0;
-
-fail:
-	if (ctx && !IS_ERR(ctx))
-		eventfd_ctx_put(ctx);
-
-	if (file && !IS_ERR(file))
-		fput(file);
-
+err_busy:
+	eventfd_ctx_put(ctx);
+err_ctx:
+	fdput(irqfd);
+err_fd:
 	kfree(virqfd);
 
 	return ret;
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 842f4507883e..1eab4ace0671 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1109,7 +1109,7 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 		 * We can't use anon_inode_getfd() because we need to modify
 		 * the f_mode flags directly to allow more than just ioctls
 		 */
-		ret = get_unused_fd();
+		ret = get_unused_fd_flags(O_CLOEXEC);
 		if (ret < 0) {
 			device->ops->release(device->device_data);
 			break;
@@ -1353,6 +1353,68 @@ static const struct file_operations vfio_device_fops = {
 };
 
 /**
+ * External user API, exported by symbols to be linked dynamically.
+ *
+ * The protocol includes:
+ *  1. do normal VFIO init operation:
+ *	- opening a new container;
+ *	- attaching group(s) to it;
+ *	- setting an IOMMU driver for a container.
+ * When IOMMU is set for a container, all groups in it are
+ * considered ready to use by an external user.
+ *
+ * 2. User space passes a group fd to an external user.
+ * The external user calls vfio_group_get_external_user()
+ * to verify that:
+ *	- the group is initialized;
+ *	- IOMMU is set for it.
+ * If both checks passed, vfio_group_get_external_user()
+ * increments the container user counter to prevent
+ * the VFIO group from disposal before KVM exits.
+ *
+ * 3. The external user calls vfio_external_user_iommu_id()
+ * to know an IOMMU ID.
+ *
+ * 4. When the external KVM finishes, it calls
+ * vfio_group_put_external_user() to release the VFIO group.
+ * This call decrements the container user counter.
+ */
+struct vfio_group *vfio_group_get_external_user(struct file *filep)
+{
+	struct vfio_group *group = filep->private_data;
+
+	if (filep->f_op != &vfio_group_fops)
+		return ERR_PTR(-EINVAL);
+
+	if (!atomic_inc_not_zero(&group->container_users))
+		return ERR_PTR(-EINVAL);
+
+	if (!group->container->iommu_driver ||
+			!vfio_group_viable(group)) {
+		atomic_dec(&group->container_users);
+		return ERR_PTR(-EINVAL);
+	}
+
+	vfio_group_get(group);
+
+	return group;
+}
+EXPORT_SYMBOL_GPL(vfio_group_get_external_user);
+
+void vfio_group_put_external_user(struct vfio_group *group)
+{
+	vfio_group_put(group);
+	vfio_group_try_dissolve_container(group);
+}
+EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
+
+int vfio_external_user_iommu_id(struct vfio_group *group)
+{
+	return iommu_group_id(group->iommu_group);
+}
+EXPORT_SYMBOL_GPL(vfio_external_user_iommu_id);
+
+/**
  * Module/class support
  */
 static char *vfio_devnode(struct device *dev, umode_t *mode)