[dpdk-dev] [PATCH V19 1/4] bus/pci: introduce device hot unplug handle

[Jeff Guo <jia.guo@intel.com>]

As of device hot unplug, we need some preparatory measures so that we will
not encounter memory fault after device be plug out of the system,
and also let we could recover the running data path but not been break.
This allows the buses to handle device hot unplug event.
The patch only enable the ops in pci bus, when handle device hot unplug
event, remap a dummy memory to avoid bus read/write error.
Other buses could accordingly implement this ops specific by themselves.

Signed-off-by: Jeff Guo <jia.guo@intel.com>
---
v19->v18:
fix some typo and squeeze patch
---
 drivers/bus/pci/pci_common.c            | 42 +++++++++++++++++++++++++++++++++
 drivers/bus/pci/pci_common_uio.c        | 32 +++++++++++++++++++++++++
 drivers/bus/pci/private.h               | 12 ++++++++++
 lib/librte_eal/common/include/rte_bus.h | 15 ++++++++++++
 4 files changed, 101 insertions(+)

diff --git a/drivers/bus/pci/pci_common.c b/drivers/bus/pci/pci_common.c
index 2a00f36..09192ed 100644
--- a/drivers/bus/pci/pci_common.c
+++ b/drivers/bus/pci/pci_common.c
@@ -474,6 +474,47 @@ pci_find_device(const struct rte_device *start, rte_dev_cmp_t cmp,
 }
 
 static int
+pci_handle_hot_unplug(struct rte_device *dev)
+{
+	struct rte_pci_device *pdev;
+	int ret;
+
+	if (dev == NULL)
+		return -EINVAL;
+
+	pdev = RTE_DEV_TO_PCI(dev);
+
+	/* remap resources for devices */
+	switch (pdev->kdrv) {
+	case RTE_KDRV_VFIO:
+#ifdef VFIO_PRESENT
+		/* TODO */
+#endif
+		break;
+	case RTE_KDRV_IGB_UIO:
+	case RTE_KDRV_UIO_GENERIC:
+		if (rte_eal_using_phys_addrs()) {
+			/* map resources for devices that use uio */
+			ret = pci_uio_remap_resource(pdev);
+		}
+		break;
+	case RTE_KDRV_NIC_UIO:
+		ret = pci_uio_remap_resource(pdev);
+		break;
+	default:
+		RTE_LOG(DEBUG, EAL,
+			"  Not managed by a supported kernel driver, skipped\n");
+		ret = -1;
+		break;
+	}
+
+	if (ret != 0)
+		RTE_LOG(ERR, EAL, "failed to handle hot unplug of %s",
+			pdev->name);
+	return ret;
+}
+
+static int
 pci_plug(struct rte_device *dev)
 {
 	return pci_probe_all_drivers(RTE_DEV_TO_PCI(dev));
@@ -503,6 +544,7 @@ struct rte_pci_bus rte_pci_bus = {
 		.unplug = pci_unplug,
 		.parse = pci_parse,
 		.get_iommu_class = rte_pci_get_iommu_class,
+		.handle_hot_unplug = pci_handle_hot_unplug,
 	},
 	.device_list = TAILQ_HEAD_INITIALIZER(rte_pci_bus.device_list),
 	.driver_list = TAILQ_HEAD_INITIALIZER(rte_pci_bus.driver_list),
diff --git a/drivers/bus/pci/pci_common_uio.c b/drivers/bus/pci/pci_common_uio.c
index 54bc20b..31a4094 100644
--- a/drivers/bus/pci/pci_common_uio.c
+++ b/drivers/bus/pci/pci_common_uio.c
@@ -146,6 +146,38 @@ pci_uio_unmap(struct mapped_pci_resource *uio_res)
 	}
 }
 
+/* remap the PCI resource of a PCI device in private virtual memory */
+int
+pci_uio_remap_resource(struct rte_pci_device *dev)
+{
+	int i;
+	void *map_address;
+
+	if (dev == NULL)
+		return -1;
+
+	/* Remap all BARs */
+	for (i = 0; i != PCI_MAX_RESOURCE; i++) {
+		/* skip empty BAR */
+		if (dev->mem_resource[i].phys_addr == 0)
+			continue;
+		pci_unmap_resource(dev->mem_resource[i].addr,
+				(size_t)dev->mem_resource[i].len);
+		map_address = pci_map_resource(
+				dev->mem_resource[i].addr, -1, 0,
+				(size_t)dev->mem_resource[i].len,
+				MAP_ANONYMOUS | MAP_FIXED);
+		if (map_address == MAP_FAILED) {
+			RTE_LOG(ERR, EAL,
+				"Cannot remap resource for device %s\n",
+				dev->name);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 static struct mapped_pci_resource *
 pci_uio_find_resource(struct rte_pci_device *dev)
 {
diff --git a/drivers/bus/pci/private.h b/drivers/bus/pci/private.h
index 88fa587..7a862ef 100644
--- a/drivers/bus/pci/private.h
+++ b/drivers/bus/pci/private.h
@@ -173,6 +173,18 @@ void pci_uio_free_resource(struct rte_pci_device *dev,
 		struct mapped_pci_resource *uio_res);
 
 /**
+ * remap the pci uio resource..
+ *
+ * @param dev
+ *   Point to the struct rte pci device.
+ * @return
+ *   - On success, zero.
+ *   - On failure, a negative value.
+ */
+int
+pci_uio_remap_resource(struct rte_pci_device *dev);
+
+/**
  * Map device memory to uio resource
  *
  * This function is private to EAL.
diff --git a/lib/librte_eal/common/include/rte_bus.h b/lib/librte_eal/common/include/rte_bus.h
index 6fb0834..729ff34 100644
--- a/lib/librte_eal/common/include/rte_bus.h
+++ b/lib/librte_eal/common/include/rte_bus.h
@@ -168,6 +168,19 @@ typedef int (*rte_bus_unplug_t)(struct rte_device *dev);
 typedef int (*rte_bus_parse_t)(const char *name, void *addr);
 
 /**
+ * Implementation specific hot unplug handler function which is responsible
+ * for handle the failure when hot unplug the device, guaranty the system
+ * would not crash in the case.
+ * @param dev
+ *	Pointer of the device structure.
+ *
+ * @return
+ *	0 on success.
+ *	!0 on error.
+ */
+typedef int (*rte_bus_handle_hot_unplug_t)(struct rte_device *dev);
+
+/**
  * Bus scan policies
  */
 enum rte_bus_scan_mode {
@@ -209,6 +222,8 @@ struct rte_bus {
 	rte_bus_plug_t plug;         /**< Probe single device for drivers */
 	rte_bus_unplug_t unplug;     /**< Remove single device from driver */
 	rte_bus_parse_t parse;       /**< Parse a device name */
+	rte_bus_handle_hot_unplug_t handle_hot_unplug; /**< handle hot unplug
+							device event */
 	struct rte_bus_conf conf;    /**< Bus configuration */
 	rte_bus_get_iommu_class_t get_iommu_class; /**< Get iommu class */
 };
-- 
2.7.4