vdpa/mlx5: Add multiqueue support

Multiqueue support requires additional virtio_net_q objects to be added
or removed per the configured number of queue pairs. In addition the RQ
tables needs to be modified to match the number of configured receive
queues so the packets are dispatched to the right virtqueue according to
the hash result.

Note: qemu v6.0.0 is broken when the device requests more than two data
queues; no net device will be created for the vdpa device. To avoid
this, one should specify mq=off to qemu. In this case it will end up
with a single queue.
Signed-off-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20210823052123.14909-7-elic@nvidia.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/mlx5/core/mlx5_vdpa.h

@@ -91,6 +91,7 @@ int mlx5_vdpa_get_null_mkey(struct mlx5_vdpa_dev *dev, u32 *null_mkey);
 int mlx5_vdpa_create_tis(struct mlx5_vdpa_dev *mvdev, void *in, u32 *tisn);
 void mlx5_vdpa_destroy_tis(struct mlx5_vdpa_dev *mvdev, u32 tisn);
 int mlx5_vdpa_create_rqt(struct mlx5_vdpa_dev *mvdev, void *in, int inlen, u32 *rqtn);
+int mlx5_vdpa_modify_rqt(struct mlx5_vdpa_dev *mvdev, void *in, int inlen, u32 rqtn);
 void mlx5_vdpa_destroy_rqt(struct mlx5_vdpa_dev *mvdev, u32 rqtn);
 int mlx5_vdpa_create_tir(struct mlx5_vdpa_dev *mvdev, void *in, u32 *tirn);
 void mlx5_vdpa_destroy_tir(struct mlx5_vdpa_dev *mvdev, u32 tirn);

drivers/vdpa/mlx5/core/resources.c

@@ -129,6 +129,16 @@ int mlx5_vdpa_create_rqt(struct mlx5_vdpa_dev *mvdev, void *in, int inlen, u32 *
 	return err;
 }
 
+int mlx5_vdpa_modify_rqt(struct mlx5_vdpa_dev *mvdev, void *in, int inlen, u32 rqtn)
+{
+	u32 out[MLX5_ST_SZ_DW(create_rqt_out)] = {};
+
+	MLX5_SET(modify_rqt_in, in, uid, mvdev->res.uid);
+	MLX5_SET(modify_rqt_in, in, rqtn, rqtn);
+	MLX5_SET(modify_rqt_in, in, opcode, MLX5_CMD_OP_MODIFY_RQT);
+	return mlx5_cmd_exec(mvdev->mdev, in, inlen, out, sizeof(out));
+}
+
 void mlx5_vdpa_destroy_rqt(struct mlx5_vdpa_dev *mvdev, u32 rqtn)
 {
 	u32 in[MLX5_ST_SZ_DW(destroy_rqt_in)] = {};

drivers/vdpa/mlx5/net/mlx5_vnet.c

@@ -133,7 +133,7 @@ struct mlx5_vdpa_virtqueue {
 /* We will remove this limitation once mlx5_vdpa_alloc_resources()
  * provides for driver space allocation
  */
-#define MLX5_MAX_SUPPORTED_VQS 2
+#define MLX5_MAX_SUPPORTED_VQS 16
 
 static bool is_index_valid(struct mlx5_vdpa_dev *mvdev, u16 idx)
 {
@@ -184,6 +184,23 @@ static bool mlx5_vdpa_debug;
 			mlx5_vdpa_info(mvdev, "%s\n", #_status);                                   \
 	} while (0)
 
+/* TODO: cross-endian support */
+static inline bool mlx5_vdpa_is_little_endian(struct mlx5_vdpa_dev *mvdev)
+{
+	return virtio_legacy_is_little_endian() ||
+		(mvdev->actual_features & BIT_ULL(VIRTIO_F_VERSION_1));
+}
+
+static u16 mlx5vdpa16_to_cpu(struct mlx5_vdpa_dev *mvdev, __virtio16 val)
+{
+	return __virtio16_to_cpu(mlx5_vdpa_is_little_endian(mvdev), val);
+}
+
+static __virtio16 cpu_to_mlx5vdpa16(struct mlx5_vdpa_dev *mvdev, u16 val)
+{
+	return __cpu_to_virtio16(mlx5_vdpa_is_little_endian(mvdev), val);
+}
+
 static inline u32 mlx5_vdpa_max_qps(int max_vqs)
 {
 	return max_vqs / 2;
@@ -191,6 +208,9 @@ static inline u32 mlx5_vdpa_max_qps(int max_vqs)
 
 static u16 ctrl_vq_idx(struct mlx5_vdpa_dev *mvdev)
 {
+	if (!(mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_MQ)))
+		return 2;
+
 	return 2 * mlx5_vdpa_max_qps(mvdev->max_vqs);
 }
 
@@ -1126,10 +1146,8 @@ static int setup_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
 	if (!mvq->num_ent)
 		return 0;
 
-	if (mvq->initialized) {
-		mlx5_vdpa_warn(&ndev->mvdev, "attempt re init\n");
-		return -EINVAL;
-	}
+	if (mvq->initialized)
+		return 0;
 
 	err = cq_create(ndev, idx, mvq->num_ent);
 	if (err)
@@ -1216,19 +1234,20 @@ static void teardown_vq(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *
 
 static int create_rqt(struct mlx5_vdpa_net *ndev)
 {
-	int log_max_rqt;
 	__be32 *list;
+	int max_rqt;
 	void *rqtc;
 	int inlen;
 	void *in;
 	int i, j;
 	int err;
 
-	log_max_rqt = min_t(int, 1, MLX5_CAP_GEN(ndev->mvdev.mdev, log_max_rqt_size));
-	if (log_max_rqt < 1)
+	max_rqt = min_t(int, MLX5_MAX_SUPPORTED_VQS / 2,
+			1 << MLX5_CAP_GEN(ndev->mvdev.mdev, log_max_rqt_size));
+	if (max_rqt < 1)
 		return -EOPNOTSUPP;
 
-	inlen = MLX5_ST_SZ_BYTES(create_rqt_in) + (1 << log_max_rqt) * MLX5_ST_SZ_BYTES(rq_num);
+	inlen = MLX5_ST_SZ_BYTES(create_rqt_in) + max_rqt * MLX5_ST_SZ_BYTES(rq_num);
 	in = kzalloc(inlen, GFP_KERNEL);
 	if (!in)
 		return -ENOMEM;
@@ -1237,10 +1256,9 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
 	rqtc = MLX5_ADDR_OF(create_rqt_in, in, rqt_context);
 
 	MLX5_SET(rqtc, rqtc, list_q_type, MLX5_RQTC_LIST_Q_TYPE_VIRTIO_NET_Q);
-	MLX5_SET(rqtc, rqtc, rqt_max_size, 1 << log_max_rqt);
-	MLX5_SET(rqtc, rqtc, rqt_actual_size, 1);
+	MLX5_SET(rqtc, rqtc, rqt_max_size, max_rqt);
 	list = MLX5_ADDR_OF(rqtc, rqtc, rq_num[0]);
-	for (i = 0, j = 0; j < ndev->mvdev.max_vqs; j++) {
+	for (i = 0, j = 0; j < max_rqt; j++) {
 		if (!ndev->vqs[j].initialized)
 			continue;
 
@@ -1249,6 +1267,7 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
 			i++;
 		}
 	}
+	MLX5_SET(rqtc, rqtc, rqt_actual_size, i);
 
 	err = mlx5_vdpa_create_rqt(&ndev->mvdev, in, inlen, &ndev->res.rqtn);
 	kfree(in);
@@ -1258,6 +1277,52 @@ static int create_rqt(struct mlx5_vdpa_net *ndev)
 	return 0;
 }
 
+#define MLX5_MODIFY_RQT_NUM_RQS ((u64)1)
+
+static int modify_rqt(struct mlx5_vdpa_net *ndev, int num)
+{
+	__be32 *list;
+	int max_rqt;
+	void *rqtc;
+	int inlen;
+	void *in;
+	int i, j;
+	int err;
+
+	max_rqt = min_t(int, ndev->cur_num_vqs / 2,
+			1 << MLX5_CAP_GEN(ndev->mvdev.mdev, log_max_rqt_size));
+	if (max_rqt < 1)
+		return -EOPNOTSUPP;
+
+	inlen = MLX5_ST_SZ_BYTES(modify_rqt_in) + max_rqt * MLX5_ST_SZ_BYTES(rq_num);
+	in = kzalloc(inlen, GFP_KERNEL);
+	if (!in)
+		return -ENOMEM;
+
+	MLX5_SET(modify_rqt_in, in, uid, ndev->mvdev.res.uid);
+	MLX5_SET64(modify_rqt_in, in, bitmask, MLX5_MODIFY_RQT_NUM_RQS);
+	rqtc = MLX5_ADDR_OF(modify_rqt_in, in, ctx);
+	MLX5_SET(rqtc, rqtc, list_q_type, MLX5_RQTC_LIST_Q_TYPE_VIRTIO_NET_Q);
+
+	list = MLX5_ADDR_OF(rqtc, rqtc, rq_num[0]);
+	for (i = 0, j = 0; j < num; j++) {
+		if (!ndev->vqs[j].initialized)
+			continue;
+
+		if (!vq_is_tx(ndev->vqs[j].index)) {
+			list[i] = cpu_to_be32(ndev->vqs[j].virtq_id);
+			i++;
+		}
+	}
+	MLX5_SET(rqtc, rqtc, rqt_actual_size, i);
+	err = mlx5_vdpa_modify_rqt(&ndev->mvdev, in, inlen, ndev->res.rqtn);
+	kfree(in);
+	if (err)
+		return err;
+
+	return 0;
+}
+
 static void destroy_rqt(struct mlx5_vdpa_net *ndev)
 {
 	mlx5_vdpa_destroy_rqt(&ndev->mvdev, ndev->res.rqtn);
@@ -1417,6 +1482,77 @@ static virtio_net_ctrl_ack handle_ctrl_mac(struct mlx5_vdpa_dev *mvdev, u8 cmd)
 	return status;
 }
 
+static int change_num_qps(struct mlx5_vdpa_dev *mvdev, int newqps)
+{
+	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
+	int cur_qps = ndev->cur_num_vqs / 2;
+	int err;
+	int i;
+
+	if (cur_qps > newqps) {
+		err = modify_rqt(ndev, 2 * newqps);
+		if (err)
+			return err;
+
+		for (i = ndev->cur_num_vqs - 1; i >= 2 * newqps; i--)
+			teardown_vq(ndev, &ndev->vqs[i]);
+
+		ndev->cur_num_vqs = 2 * newqps;
+	} else {
+		ndev->cur_num_vqs = 2 * newqps;
+		for (i = cur_qps * 2; i < 2 * newqps; i++) {
+			err = setup_vq(ndev, &ndev->vqs[i]);
+			if (err)
+				goto clean_added;
+		}
+		err = modify_rqt(ndev, 2 * newqps);
+		if (err)
+			goto clean_added;
+	}
+	return 0;
+
+clean_added:
+	for (--i; i >= cur_qps; --i)
+		teardown_vq(ndev, &ndev->vqs[i]);
+
+	return err;
+}
+
+static virtio_net_ctrl_ack handle_ctrl_mq(struct mlx5_vdpa_dev *mvdev, u8 cmd)
+{
+	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
+	virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
+	struct mlx5_control_vq *cvq = &mvdev->cvq;
+	struct virtio_net_ctrl_mq mq;
+	size_t read;
+	u16 newqps;
+
+	switch (cmd) {
+	case VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET:
+		read = vringh_iov_pull_iotlb(&cvq->vring, &cvq->riov, (void *)&mq, sizeof(mq));
+		if (read != sizeof(mq))
+			break;
+
+		newqps = mlx5vdpa16_to_cpu(mvdev, mq.virtqueue_pairs);
+		if (ndev->cur_num_vqs == 2 * newqps) {
+			status = VIRTIO_NET_OK;
+			break;
+		}
+
+		if (newqps & (newqps - 1))
+			break;
+
+		if (!change_num_qps(mvdev, newqps))
+			status = VIRTIO_NET_OK;
+
+		break;
+	default:
+		break;
+	}
+
+	return status;
+}
+
 static void mlx5_cvq_kick_handler(struct work_struct *work)
 {
 	virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
@@ -1452,6 +1588,9 @@ static void mlx5_cvq_kick_handler(struct work_struct *work)
 		case VIRTIO_NET_CTRL_MAC:
 			status = handle_ctrl_mac(mvdev, ctrl.cmd);
 			break;
+		case VIRTIO_NET_CTRL_MQ:
+			status = handle_ctrl_mq(mvdev, ctrl.cmd);
+			break;
 
 		default:
 			break;
@@ -1709,6 +1848,7 @@ static u64 mlx5_vdpa_get_features(struct vdpa_device *vdev)
 	ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_F_ACCESS_PLATFORM);
 	ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_NET_F_CTRL_VQ);
 	ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_NET_F_CTRL_MAC_ADDR);
+	ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_NET_F_MQ);
 
 	print_features(mvdev, ndev->mvdev.mlx_features, false);
 	return ndev->mvdev.mlx_features;
@@ -1768,18 +1908,6 @@ static void teardown_virtqueues(struct mlx5_vdpa_net *ndev)
 	}
 }
 
-/* TODO: cross-endian support */
-static inline bool mlx5_vdpa_is_little_endian(struct mlx5_vdpa_dev *mvdev)
-{
-	return virtio_legacy_is_little_endian() ||
-		(mvdev->actual_features & BIT_ULL(VIRTIO_F_VERSION_1));
-}
-
-static __virtio16 cpu_to_mlx5vdpa16(struct mlx5_vdpa_dev *mvdev, u16 val)
-{
-	return __cpu_to_virtio16(mlx5_vdpa_is_little_endian(mvdev), val);
-}
-
 static void update_cvq_info(struct mlx5_vdpa_dev *mvdev)
 {
 	if (MLX5_FEATURE(mvdev, VIRTIO_NET_F_CTRL_VQ)) {
@@ -1851,15 +1979,14 @@ static u8 mlx5_vdpa_get_status(struct vdpa_device *vdev)
 static int save_channel_info(struct mlx5_vdpa_net *ndev, struct mlx5_vdpa_virtqueue *mvq)
 {
 	struct mlx5_vq_restore_info *ri = &mvq->ri;
-	struct mlx5_virtq_attr attr;
+	struct mlx5_virtq_attr attr = {};
 	int err;
 
-	if (!mvq->initialized)
-		return 0;
-
-	err = query_virtqueue(ndev, mvq, &attr);
-	if (err)
-		return err;
+	if (mvq->initialized) {
+		err = query_virtqueue(ndev, mvq, &attr);
+		if (err)
+			return err;
+	}
 
 	ri->avail_index = attr.available_index;
 	ri->used_index = attr.used_index;