virtio/user: implement get/set config messages

This will let us e.g. read device blocksize in the
upcoming vhost-blk initiator. All the public API
was already there - we've been using it for
virtio-pci. Now we're making use of it for vhost-user
as well.

Change-Id: I39eab820bb9bbff59c8b8efa79cc97d2ec7806fd
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/398828
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

lib/virtio/virtio_user.c

@@ -201,14 +201,35 @@ static void
 virtio_user_read_dev_config(struct virtio_dev *vdev, size_t offset,
 			    void *dst, int length)
 {
-	SPDK_ERRLOG("not supported offset=%zu, len=%d\n", offset, length);
+	struct virtio_user_dev *dev = vdev->ctx;
+	struct vhost_user_config cfg = {0};
+
+	cfg.offset = 0;
+	cfg.size = VHOST_USER_MAX_CONFIG_SIZE;
+
+	if (dev->ops->send_request(dev, VHOST_USER_GET_CONFIG, &cfg) < 0) {
+		SPDK_ERRLOG("get_config failed: %s\n", spdk_strerror(errno));
+		return;
+	}
+
+	memcpy(dst, cfg.region + offset, length);
 }
 
 static void
 virtio_user_write_dev_config(struct virtio_dev *vdev, size_t offset,
 			     const void *src, int length)
 {
-	SPDK_ERRLOG("not supported offset=%zu, len=%d\n", offset, length);
+	struct virtio_user_dev *dev = vdev->ctx;
+	struct vhost_user_config cfg = {0};
+
+	cfg.offset = offset;
+	cfg.size = length;
+	memcpy(cfg.region, src, length);
+
+	if (dev->ops->send_request(dev, VHOST_USER_SET_CONFIG, &cfg) < 0) {
+		SPDK_ERRLOG("set_config failed: %s\n", spdk_strerror(errno));
+		return;
+	}
 }
 
 static void

lib/virtio/virtio_user/vhost.h

@@ -41,6 +41,8 @@
 #include "spdk_internal/log.h"
 #include "spdk_internal/virtio.h"
 
+#define VHOST_USER_MAX_CONFIG_SIZE 256
+
 enum vhost_user_request {
 	VHOST_USER_NONE = 0,
 	VHOST_USER_GET_FEATURES = 1,
@@ -61,6 +63,8 @@ enum vhost_user_request {
 	VHOST_USER_SET_PROTOCOL_FEATURES = 16,
 	VHOST_USER_GET_QUEUE_NUM = 17,
 	VHOST_USER_SET_VRING_ENABLE = 18,
+	VHOST_USER_GET_CONFIG = 24,
+	VHOST_USER_SET_CONFIG = 25,
 	VHOST_USER_MAX
 };
 
@@ -88,6 +92,14 @@ struct virtio_user_backend_ops {
 			    void *arg);
 };
 
+/* get/set config msg */
+struct vhost_user_config {
+	uint32_t offset;
+	uint32_t size;
+	uint32_t flags;
+	uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
+};
+
 extern struct virtio_user_backend_ops ops_user;
 extern struct virtio_user_backend_ops ops_kernel;
 

lib/virtio/virtio_user/vhost_user.c

@@ -63,6 +63,7 @@ struct vhost_user_msg {
 		struct vhost_vring_state state;
 		struct vhost_vring_addr addr;
 		struct vhost_memory_padded memory;
+		struct vhost_user_config cfg;
 	} payload;
 	int fds[VHOST_MEMORY_MAX_NREGIONS];
 } __attribute((packed));
@@ -279,7 +280,9 @@ static const char *const vhost_msg_strings[VHOST_USER_MAX] = {
 	[VHOST_USER_SET_VRING_KICK] = "VHOST_SET_VRING_KICK",
 	[VHOST_USER_SET_MEM_TABLE] = "VHOST_SET_MEM_TABLE",
 	[VHOST_USER_SET_VRING_ENABLE] = "VHOST_SET_VRING_ENABLE",
-	[VHOST_USER_GET_QUEUE_NUM] = "VHOST_USER_GET_QUEUE_NUM"
+	[VHOST_USER_GET_QUEUE_NUM] = "VHOST_USER_GET_QUEUE_NUM",
+	[VHOST_USER_GET_CONFIG] = "VHOST_USER_GET_CONFIG",
+	[VHOST_USER_SET_CONFIG] = "VHOST_USER_SET_CONFIG",
 };
 
 static int
@@ -362,6 +365,17 @@ vhost_user_sock(struct virtio_user_dev *dev,
 		}
 		break;
 
+	case VHOST_USER_GET_CONFIG:
+		memcpy(&msg.payload.cfg, arg, sizeof(msg.payload.cfg));
+		msg.size = sizeof(msg.payload.cfg);
+		need_reply = 1;
+		break;
+
+	case VHOST_USER_SET_CONFIG:
+		memcpy(&msg.payload.cfg, arg, sizeof(msg.payload.cfg));
+		msg.size = sizeof(msg.payload.cfg);
+		break;
+
 	default:
 		SPDK_ERRLOG("trying to send unhandled msg type\n");
 		return -1;
@@ -407,6 +421,13 @@ vhost_user_sock(struct virtio_user_dev *dev,
 			memcpy(arg, &msg.payload.state,
 			       sizeof(struct vhost_vring_state));
 			break;
+		case VHOST_USER_GET_CONFIG:
+			if (msg.size != sizeof(msg.payload.cfg)) {
+				SPDK_WARNLOG("Received bad msg size\n");
+				return -1;
+			}
+			memcpy(arg, &msg.payload.cfg, sizeof(msg.payload.cfg));
+			break;
 		default:
 			SPDK_WARNLOG("Received unexpected msg type\n");
 			return -1;