Re: [PATCH v1 3/4] vdpa: Support for configuring max VQ pairs for a device

Use VDPA_ATTR_DEV_MGMTDEV_MAX_VQS to specify max number of virtqueue
pairs to configure for a vdpa device when adding a device.

Examples:
1. Create a device with 3 virtqueue pairs:
$ vdpa dev add name vdpa-a mgmtdev auxiliary/mlx5_core.sf.1 max_vqp 3

2. Read the configuration of a vdpa device
$ vdpa dev config show vdpa-a
   vdpa-a: mac 00:00:00:00:88:88 link up link_announce false max_vq_pairs 3 \
           mtu 1500
   negotiated_features CSUM GUEST_CSUM MTU MAC HOST_TSO4 HOST_TSO6 STATUS \
                       CTRL_VQ MQ CTRL_MAC_ADDR VERSION_1 ACCESS_PLATFORM

Signed-off-by: Eli Cohen <redacted>
---
  vdpa/include/uapi/linux/vdpa.h |  1 +
  vdpa/vdpa.c                    | 25 ++++++++++++++++++++++++-
  2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/vdpa/include/uapi/linux/vdpa.h b/vdpa/include/uapi/linux/vdpa.h
index 748c350450b2..a3ebf4d4d9b8 100644
--- a/vdpa/include/uapi/linux/vdpa.h
+++ b/vdpa/include/uapi/linux/vdpa.h

@@ -41,6 +41,7 @@ enum vdpa_attr {
  	VDPA_ATTR_DEV_NET_CFG_MTU,		/* u16 */
  
  	VDPA_ATTR_DEV_NEGOTIATED_FEATURES,	/* u64 */
+	VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,          /* u32 */
  
  	/* new attributes must be added above here */
  	VDPA_ATTR_MAX,

diff --git a/vdpa/vdpa.c b/vdpa/vdpa.c
index 7deab710913d..99ee828630cc 100644
--- a/vdpa/vdpa.c
+++ b/vdpa/vdpa.c

@@ -24,6 +24,7 @@
  #define VDPA_OPT_VDEV_HANDLE		BIT(3)
  #define VDPA_OPT_VDEV_MAC		BIT(4)
  #define VDPA_OPT_VDEV_MTU		BIT(5)
+#define VDPA_OPT_MAX_VQP		BIT(6)
  
  struct vdpa_opts {
  	uint64_t present; /* flags of present items */

@@ -33,6 +34,7 @@ struct vdpa_opts {
  	unsigned int device_id;
  	char mac[ETH_ALEN];
  	uint16_t mtu;
+	uint16_t max_vqp;
  };
  
  struct vdpa {

@@ -80,6 +82,7 @@ static const enum mnl_attr_data_type vdpa_policy[VDPA_ATTR_MAX + 1] = {
  	[VDPA_ATTR_DEV_MAX_VQS] = MNL_TYPE_U32,
  	[VDPA_ATTR_DEV_MAX_VQ_SIZE] = MNL_TYPE_U16,
  	[VDPA_ATTR_DEV_NEGOTIATED_FEATURES] = MNL_TYPE_U64,
+	[VDPA_ATTR_DEV_MGMTDEV_MAX_VQS] = MNL_TYPE_U32,
  };
  
  static int attr_cb(const struct nlattr *attr, void *data)

@@ -221,6 +224,8 @@ static void vdpa_opts_put(struct nlmsghdr *nlh, struct vdpa *vdpa)
  			     sizeof(opts->mac), opts->mac);
  	if (opts->present & VDPA_OPT_VDEV_MTU)
  		mnl_attr_put_u16(nlh, VDPA_ATTR_DEV_NET_CFG_MTU, opts->mtu);
+	if (opts->present & VDPA_OPT_MAX_VQP)
+		mnl_attr_put_u16(nlh, VDPA_ATTR_DEV_NET_CFG_MAX_VQP, opts->max_vqp);
  }
  
  static int vdpa_argv_parse(struct vdpa *vdpa, int argc, char **argv,

@@ -289,6 +294,14 @@ static int vdpa_argv_parse(struct vdpa *vdpa, int argc, char **argv,
  
  			NEXT_ARG_FWD();
  			o_found |= VDPA_OPT_VDEV_MTU;
+		} else if ((matches(*argv, "max_vqp")  == 0) && (o_optional & VDPA_OPT_MAX_VQP)) {
+			NEXT_ARG_FWD();
+			err = vdpa_argv_u16(vdpa, argc, argv, &opts->max_vqp);
+			if (err)
+				return err;
+
+			NEXT_ARG_FWD();
+			o_found |= VDPA_OPT_MAX_VQP;

  		} else {
  			fprintf(stderr, "Unknown option \"%s\"\n", *argv);
  			return -EINVAL;

@@ -513,6 +526,15 @@ static void pr_out_mgmtdev_show(struct vdpa *vdpa, const struct nlmsghdr *nlh,
  		pr_out_array_end(vdpa);
  	}
  
+	if (tb[VDPA_ATTR_DEV_MGMTDEV_MAX_VQS]) {
+		uint16_t num_vqs;
+
+		if (!vdpa->json_output)
+			printf("\n");
+		num_vqs = mnl_attr_get_u16(tb[VDPA_ATTR_DEV_MGMTDEV_MAX_VQS]);
+		print_uint(PRINT_ANY, "max_supported_vqs", "  max_supported_vqs %d", num_vqs);
+	}
+
  	pr_out_handle_end(vdpa);
  }
  

@@ -662,7 +684,8 @@ static int cmd_dev_add(struct vdpa *vdpa, int argc, char **argv)
  					  NLM_F_REQUEST | NLM_F_ACK);
  	err = vdpa_argv_parse_put(nlh, vdpa, argc, argv,
  				  VDPA_OPT_VDEV_MGMTDEV_HANDLE | VDPA_OPT_VDEV_NAME,
-				  VDPA_OPT_VDEV_MAC | VDPA_OPT_VDEV_MTU);
+				  VDPA_OPT_VDEV_MAC | VDPA_OPT_VDEV_MTU |
+				  VDPA_OPT_MAX_VQP);
  	if (err)
  		return err;