[v1,5/5] vfio: enable vfio hotplug by req notifier handler

diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index 686386d..8a14f92 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -17,6 +17,8 @@ 
 #include <rte_eal_memconfig.h>
 #include <rte_malloc.h>
 #include <rte_vfio.h>
+#include <rte_eal.h>
+#include <rte_bus.h>
 
 #include "eal_filesystem.h"
 
@@ -277,6 +279,92 @@  pci_vfio_setup_interrupts(struct rte_pci_device *dev, int vfio_dev_fd)
 	return -1;
 }
 
+static void
+pci_vfio_req_handler(void *param)
+{
+	struct rte_bus *bus;
+	int ret;
+	struct rte_device *device = (struct rte_device *)param;
+
+	bus = rte_bus_find_by_device(device);
+	if (bus == NULL) {
+		RTE_LOG(ERR, EAL, "Cannot find bus for device (%s)\n",
+			device->name);
+		return;
+	}
+
+	/**
+	 * vfio kernel module request user space to release allocated
+	 * resources before resources be released in kernel, so it can directly
+	 * call the bus failure handler to use the specific mechanism in
+	 * user space to handle it.
+	 */
+	ret = bus->memory_failure_handler(device);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Can not handle failure for "
+			"device (%s)\n", device->name);
+		return;
+	}
+}
+
+/* enable notifier (only enable req now) */
+static int
+pci_vfio_enable_notifier(struct rte_pci_device *dev, int vfio_dev_fd)
+{
+	int ret;
+	int fd = -1;
+
+	/* set up an eventfd for req notifier */
+	fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+	if (fd < 0) {
+		RTE_LOG(ERR, EAL, "Cannot set up eventfd, "
+				"error %i (%s)\n", errno, strerror(errno));
+		return -1;
+	}
+
+	dev->req_notifier_handler.fd = fd;
+	dev->req_notifier_handler.type = RTE_INTR_HANDLE_VFIO_REQ;
+	dev->req_notifier_handler.vfio_dev_fd = vfio_dev_fd;
+	ret = rte_intr_callback_register(&dev->req_notifier_handler,
+					 pci_vfio_req_handler,
+					 (void *)&dev->device);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Fail to register req notifier handler.\n");
+		return -1;
+	}
+
+	ret = rte_intr_enable(&dev->req_notifier_handler);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Fail to enable req notifier.\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+/*disable notifier (only disable req now) */
+static int
+pci_vfio_disable_notifier(struct rte_pci_device *dev)
+{
+	int ret;
+
+	ret = rte_intr_callback_unregister(&dev->req_notifier_handler,
+					 pci_vfio_req_handler,
+					 (void *)&dev->device);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "fail to unregister req notifier handler.\n");
+		return -1;
+	}
+
+	ret = rte_intr_enable(&dev->req_notifier_handler);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "fail to disable req notifier.\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 static int
 pci_vfio_is_ioport_bar(int vfio_dev_fd, int bar_index)
 {
@@ -430,6 +518,7 @@  pci_vfio_map_resource_primary(struct rte_pci_device *dev)
 	struct pci_map *maps;
 
 	dev->intr_handle.fd = -1;
+	dev->req_notifier_handler.fd = -1;
 
 	/* store PCI address string */
 	snprintf(pci_addr, sizeof(pci_addr), PCI_PRI_FMT,
@@ -521,6 +610,11 @@  pci_vfio_map_resource_primary(struct rte_pci_device *dev)
 		goto err_vfio_res;
 	}
 
+	if (pci_vfio_enable_notifier(dev, vfio_dev_fd) != 0) {
+		RTE_LOG(ERR, EAL, "Error setting up notifier!\n");
+		return -1;
+	}
+
 	TAILQ_INSERT_TAIL(vfio_res_list, vfio_res, next);
 
 	return 0;
@@ -546,6 +640,7 @@  pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
 	struct pci_map *maps;
 
 	dev->intr_handle.fd = -1;
+	dev->req_notifier_handler.fd = -1;
 
 	/* store PCI address string */
 	snprintf(pci_addr, sizeof(pci_addr), PCI_PRI_FMT,
@@ -586,6 +681,7 @@  pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
 
 	/* we need save vfio_dev_fd, so it can be used during release */
 	dev->intr_handle.vfio_dev_fd = vfio_dev_fd;
+	dev->req_notifier_handler.vfio_dev_fd = vfio_dev_fd;
 
 	return 0;
 err_vfio_dev_fd:
@@ -658,12 +754,20 @@  pci_vfio_unmap_resource_primary(struct rte_pci_device *dev)
 	snprintf(pci_addr, sizeof(pci_addr), PCI_PRI_FMT,
 			loc->domain, loc->bus, loc->devid, loc->function);
 
+	pci_vfio_disable_notifier(dev);
+
 	if (close(dev->intr_handle.fd) < 0) {
 		RTE_LOG(INFO, EAL, "Error when closing eventfd file descriptor for %s\n",
 			pci_addr);
 		return -1;
 	}
 
+	if (close(dev->req_notifier_handler.fd) < 0) {
+		RTE_LOG(INFO, EAL, "Error when closing req eventfd file "
+			"descriptor for %s\n", pci_addr);
+		return -1;
+	}
+
 	if (pci_vfio_set_bus_master(dev->intr_handle.vfio_dev_fd, false)) {
 		RTE_LOG(ERR, EAL, "  %s cannot unset bus mastering for PCI device!\n",
 				pci_addr);
diff --git a/drivers/bus/pci/pci_common.c b/drivers/bus/pci/pci_common.c
index b8f3244..21a7397 100644
--- a/drivers/bus/pci/pci_common.c
+++ b/drivers/bus/pci/pci_common.c
@@ -446,6 +446,16 @@  pci_memory_failure_handler(struct rte_device *dev)
 		return -1;
 
 	switch (pdev->kdrv) {
+	case RTE_KDRV_VFIO:
+		/**
+		 * vfio kernel module guaranty the pci device would not be
+		 * deleted until the user space release the resource, so no
+		 * need to remap mmio resource here, just directly notify
+		 * the req event to the user space to handle it.
+		 */
+		rte_dev_event_callback_process(dev->name,
+					       RTE_DEV_EVENT_REQ);
+		break;
 	case RTE_KDRV_IGB_UIO:
 	case RTE_KDRV_UIO_GENERIC:
 	case RTE_KDRV_NIC_UIO:
diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index da1e9a6..74694c4 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -4424,6 +4424,7 @@  eth_dev_event_callback(const char *device_name, enum rte_dev_event_type type,
 	struct rte_eth_dev *eth_dev = (struct rte_eth_dev *)arg;
 
 	switch (type) {
+	case RTE_DEV_EVENT_REQ:
 	case RTE_DEV_EVENT_REMOVE:
 		RTE_ETHDEV_LOG(INFO, "The device %s has been removed!\n",
 			       device_name);