[dpdk-dev] [PATCH 3/7] net/virtio: introduce Vhost-vDPA backend type

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Introduce virtio_user_backend_type function and its enum in
order to support more than two backends with vDPA backend
addition.
Backend type is determined by checking the virtio-user control
file information at runtime.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
---
 .../net/virtio/virtio_user/virtio_user_dev.c  | 86 +++++++++++++++----
 .../net/virtio/virtio_user/virtio_user_dev.h  | 10 ++-
 drivers/net/virtio/virtio_user_ethdev.c       |  3 +-
 3 files changed, 79 insertions(+), 20 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c b/drivers/net/virtio/virtio_user/virtio_user_dev.c
index 2a0c861085..93274b2a94 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
@@ -12,6 +12,8 @@
 #include <sys/eventfd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <linux/major.h>
 
 #include <rte_string_fns.h>
 #include <rte_eal_memconfig.h>
@@ -111,15 +113,55 @@ virtio_user_queue_setup(struct virtio_user_dev *dev,
 	return 0;
 }
 
-int
-is_vhost_user_by_type(const char *path)
+static uint32_t
+vdpa_dynamic_major_num(void)
+{
+	FILE *fp;
+	char *line = NULL;
+	size_t size;
+	char name[11];
+	bool found = false;
+	uint32_t num;
+
+	fp = fopen("/proc/devices", "r");
+	if (fp == NULL) {
+		PMD_INIT_LOG(ERR, "Cannot open /proc/devices: %s",
+			     strerror(errno));
+		return UNNAMED_MAJOR;
+	}
+
+	while (getline(&line, &size, fp) > 0) {
+		char *stripped = line + strspn(line, " ");
+		if ((sscanf(stripped, "%u %10s", &num, name) == 2) &&
+		    (strncmp(name, "vhost-vdpa", 10) == 0)) {
+			found = true;
+			break;
+		}
+	}
+	fclose(fp);
+	return found ? num : UNNAMED_MAJOR;
+}
+
+enum virtio_user_backend_type
+virtio_user_backend_type(const char *path)
 {
 	struct stat sb;
 
-	if (stat(path, &sb) == -1)
-		return 0;
+	if (stat(path, &sb) == -1) {
+		PMD_INIT_LOG(ERR, "Stat fails: %s (%s)\n", path,
+			     strerror(errno));
+		return VIRTIO_USER_BACKEND_UNKNOWN;
+	}
 
-	return S_ISSOCK(sb.st_mode);
+	if (S_ISSOCK(sb.st_mode)) {
+		return VIRTIO_USER_BACKEND_VHOST_USER;
+	} else if (S_ISCHR(sb.st_mode)) {
+		if (major(sb.st_rdev) == MISC_MAJOR)
+			return VIRTIO_USER_BACKEND_VHOST_KERNEL;
+		if (major(sb.st_rdev) == vdpa_dynamic_major_num())
+			return VIRTIO_USER_BACKEND_VHOST_VDPA;
+	}
+	return VIRTIO_USER_BACKEND_UNKNOWN;
 }
 
 int
@@ -144,7 +186,8 @@ virtio_user_start_device(struct virtio_user_dev *dev)
 	rte_mcfg_mem_read_lock();
 	pthread_mutex_lock(&dev->mutex);
 
-	if (is_vhost_user_by_type(dev->path) && dev->vhostfd < 0)
+	if (virtio_user_backend_type(dev->path) ==
+		VIRTIO_USER_BACKEND_VHOST_USER && dev->vhostfd < 0)
 		goto error;
 
 	/* Step 0: tell vhost to create queues */
@@ -359,17 +402,19 @@ virtio_user_dev_setup(struct virtio_user_dev *dev)
 	dev->vhostfds = NULL;
 	dev->tapfds = NULL;
 
+	dev->backend_type = virtio_user_backend_type(dev->path);
+
 	if (dev->is_server) {
-		if (access(dev->path, F_OK) == 0 &&
-		    !is_vhost_user_by_type(dev->path)) {
-			PMD_DRV_LOG(ERR, "Server mode doesn't support vhost-kernel!");
+		if (dev->backend_type != VIRTIO_USER_BACKEND_VHOST_USER) {
+			PMD_DRV_LOG(ERR, "Server mode only supports vhost-user!");
 			return -1;
 		}
 		dev->ops = &virtio_ops_user;
 	} else {
-		if (is_vhost_user_by_type(dev->path)) {
+		if (dev->backend_type == VIRTIO_USER_BACKEND_VHOST_USER) {
 			dev->ops = &virtio_ops_user;
-		} else {
+		} else if (dev->backend_type ==
+					VIRTIO_USER_BACKEND_VHOST_KERNEL) {
 			dev->ops = &virtio_ops_kernel;
 
 			dev->vhostfds = malloc(dev->max_queue_pairs *
@@ -457,7 +502,8 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 		return -1;
 	}
 
-	if (!is_vhost_user_by_type(dev->path))
+	if (virtio_user_backend_type(dev->path) !=
+					VIRTIO_USER_BACKEND_VHOST_USER)
 		dev->unsupported_features |=
 			(1ULL << VHOST_USER_F_PROTOCOL_FEATURES);
 
@@ -505,8 +551,6 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 		dev->device_features = VIRTIO_USER_SUPPORTED_FEATURES;
 	}
 
-
-
 	if (!mrg_rxbuf)
 		dev->unsupported_features |= (1ull << VIRTIO_NET_F_MRG_RXBUF);
 
@@ -539,7 +583,8 @@ virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 	}
 
 	/* The backend will not report this feature, we add it explicitly */
-	if (is_vhost_user_by_type(dev->path))
+	if (virtio_user_backend_type(dev->path) ==
+					VIRTIO_USER_BACKEND_VHOST_USER)
 		dev->frontend_features |= (1ull << VIRTIO_NET_F_STATUS);
 
 	/*
@@ -790,9 +835,11 @@ virtio_user_send_status_update(struct virtio_user_dev *dev, uint8_t status)
 {
 	int ret;
 	uint64_t arg = status;
+	enum virtio_user_backend_type backend_type =
+				virtio_user_backend_type(dev->path);
 
 	/* Vhost-user only for now */
-	if (!is_vhost_user_by_type(dev->path))
+	if (backend_type != VIRTIO_USER_BACKEND_VHOST_USER)
 		return 0;
 
 	if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_STATUS)))
@@ -813,9 +860,11 @@ virtio_user_update_status(struct virtio_user_dev *dev)
 {
 	uint64_t ret;
 	int err;
+	enum virtio_user_backend_type backend_type =
+				virtio_user_backend_type(dev->path);
 
 	/* Vhost-user only for now */
-	if (!is_vhost_user_by_type(dev->path))
+	if (backend_type != VIRTIO_USER_BACKEND_VHOST_USER)
 		return 0;
 
 	if (!(dev->protocol_features & (1UL << VHOST_USER_PROTOCOL_F_STATUS)))
@@ -828,7 +877,8 @@ virtio_user_update_status(struct virtio_user_dev *dev)
 		return -1;
 	}
 	if (ret > UINT8_MAX) {
-		PMD_INIT_LOG(ERR, "Invalid VHOST_USER_GET_STATUS response 0x%" PRIx64 "\n", ret);
+		PMD_INIT_LOG(ERR, "Invalid VHOST_USER_GET_STATUS "
+				"response 0x%" PRIx64 "\n", ret);
 		return -1;
 	}
 
diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.h b/drivers/net/virtio/virtio_user/virtio_user_dev.h
index 9377d5ba66..4bb7cdbd26 100644
--- a/drivers/net/virtio/virtio_user/virtio_user_dev.h
+++ b/drivers/net/virtio/virtio_user/virtio_user_dev.h
@@ -10,6 +10,13 @@
 #include "../virtio_pci.h"
 #include "../virtio_ring.h"
 
+enum virtio_user_backend_type {
+	VIRTIO_USER_BACKEND_UNKNOWN,
+	VIRTIO_USER_BACKEND_VHOST_USER,
+	VIRTIO_USER_BACKEND_VHOST_KERNEL,
+	VIRTIO_USER_BACKEND_VHOST_VDPA,
+};
+
 struct virtio_user_queue {
 	uint16_t used_idx;
 	bool avail_wrap_counter;
@@ -17,6 +24,7 @@ struct virtio_user_queue {
 };
 
 struct virtio_user_dev {
+	enum virtio_user_backend_type backend_type;
 	/* for vhost_user backend */
 	int		vhostfd;
 	int		listenfd;   /* listening fd */
@@ -60,7 +68,7 @@ struct virtio_user_dev {
 	bool		started;
 };
 
-int is_vhost_user_by_type(const char *path);
+enum virtio_user_backend_type virtio_user_backend_type(const char *path);
 int virtio_user_start_device(struct virtio_user_dev *dev);
 int virtio_user_stop_device(struct virtio_user_dev *dev);
 int virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
diff --git a/drivers/net/virtio/virtio_user_ethdev.c b/drivers/net/virtio/virtio_user_ethdev.c
index 60d17af888..2163d0e30d 100644
--- a/drivers/net/virtio/virtio_user_ethdev.c
+++ b/drivers/net/virtio/virtio_user_ethdev.c
@@ -632,7 +632,8 @@ virtio_user_pmd_probe(struct rte_vdev_device *dev)
 	}
 
 	if (rte_kvargs_count(kvlist, VIRTIO_USER_ARG_INTERFACE_NAME) == 1) {
-		if (is_vhost_user_by_type(path)) {
+		if (virtio_user_backend_type(path) !=
+				VIRTIO_USER_BACKEND_VHOST_KERNEL) {
 			PMD_INIT_LOG(ERR,
 				"arg %s applies only to vhost-kernel backend",
 				VIRTIO_USER_ARG_INTERFACE_NAME);
-- 
2.26.2