Virtio spec allows the device to specify the per virtqueue max queue
size. vDPA needs to adapt to this flexibility. E.g Qemu advertise a
small control virtqueue for virtio-net.

So this patch adds a index parameter to get_vq_num_max bus operations
for the device to report its per virtqueue max queue size.

Both VHOST_VDPA_GET_VRING_NUM and VDPA_ATTR_DEV_MAX_VQ_SIZE assume a
global maximum size. So we iterate all the virtqueues to return the
minimal size in this case. Actually, the VHOST_VDPA_GET_VRING_NUM is
not a must for the userspace. Userspace may choose to check the
VHOST_SET_VRING_NUM for proving or validating the maximum virtqueue
size. Anyway, we can invent a per vq version of
VHOST_VDPA_GET_VRING_NUM in the future if it's necessary.

Signed-off-by: Jason Wang <redacted>
---
 drivers/vdpa/ifcvf/ifcvf_main.c   |  2 +-
 drivers/vdpa/mlx5/net/mlx5_vnet.c |  2 +-
 drivers/vdpa/vdpa.c               | 22 +++++++++++++++++++++-
 drivers/vdpa/vdpa_sim/vdpa_sim.c  |  2 +-
 drivers/vdpa/virtio_pci/vp_vdpa.c |  2 +-
 drivers/vhost/vdpa.c              |  9 ++++++---
 drivers/virtio/virtio_vdpa.c      |  2 +-
 include/linux/vdpa.h              |  5 ++++-
 8 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
index ab0ab5cf0f6e..646b340db2af 100644
--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c

@@ -254,7 +254,7 @@ static void ifcvf_vdpa_set_status(struct vdpa_device *vdpa_dev, u8 status)
        ifcvf_set_status(vf, status);
 }

-static u16 ifcvf_vdpa_get_vq_num_max(struct vdpa_device *vdpa_dev)
+static u16 ifcvf_vdpa_get_vq_num_max(struct vdpa_device *vdpa_dev, u16 qid)
 {
        return IFCVF_QUEUE_MAX;
 }

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index dda5dc6f7737..afd6114d07b0 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c

@@ -1584,7 +1584,7 @@ static void mlx5_vdpa_set_config_cb(struct vdpa_device *vdev, struct vdpa_callba
 }

 #define MLX5_VDPA_MAX_VQ_ENTRIES 256
-static u16 mlx5_vdpa_get_vq_num_max(struct vdpa_device *vdev)
+static u16 mlx5_vdpa_get_vq_num_max(struct vdpa_device *vdev, u16 idx)
 {
        return MLX5_VDPA_MAX_VQ_ENTRIES;
 }

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index bb3f1d1f0422..d77d59811389 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c

@@ -239,6 +239,26 @@ void vdpa_unregister_driver(struct vdpa_driver *drv)
 }
 EXPORT_SYMBOL_GPL(vdpa_unregister_driver);

+/**
+ * vdpa_get_vq_num_max - get the maximum virtqueue size
+ * @vdev: vdpa device
+ */
+u16 vdpa_get_vq_num_max(struct vdpa_device *vdev)
+{
+       const struct vdpa_config_ops *ops = vdev->config;
+       u16 s, size = ops->get_vq_num_max(vdev, 0);
+       int i;
+
+       for (i = 1; i < vdev->nvqs; i++) {
+               s = ops->get_vq_num_max(vdev, i);
+               if (s && s < size)
+                       size = s;
+       }
+
+       return size;
+}
+EXPORT_SYMBOL_GPL(vdpa_get_vq_num_max);
+
 /**
  * vdpa_mgmtdev_register - register a vdpa management device
  *

@@ -502,7 +522,7 @@ vdpa_dev_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq

        device_id = vdev->config->get_device_id(vdev);
        vendor_id = vdev->config->get_vendor_id(vdev);
-       max_vq_size = vdev->config->get_vq_num_max(vdev);
+       max_vq_size = vdpa_get_vq_num_max(vdev);

        err = -EMSGSIZE;
        if (nla_put_string(msg, VDPA_ATTR_DEV_NAME, dev_name(&vdev->dev)))

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 98f793bc9376..49e29056f164 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -422,7 +422,7 @@ static void vdpasim_set_config_cb(struct vdpa_device *vdpa,
        /* We don't support config interrupt */
 }

-static u16 vdpasim_get_vq_num_max(struct vdpa_device *vdpa)
+static u16 vdpasim_get_vq_num_max(struct vdpa_device *vdpa, u16 idx)
 {
        return VDPASIM_QUEUE_MAX;
 }

diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
index c76ebb531212..2926641fb586 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c

@@ -195,7 +195,7 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
                vp_vdpa_free_irq(vp_vdpa);
 }

-static u16 vp_vdpa_get_vq_num_max(struct vdpa_device *vdpa)
+static u16 vp_vdpa_get_vq_num_max(struct vdpa_device *vdpa, u16 qid)
 {
        return VP_VDPA_QUEUE_MAX;
 }

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index fb41db3da611..c9ec395b8c42 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -289,11 +289,14 @@ static long vhost_vdpa_set_features(struct vhost_vdpa *v, u64 __user *featurep)

 static long vhost_vdpa_get_vring_num(struct vhost_vdpa *v, u16 __user *argp)
 {
-       struct vdpa_device *vdpa = v->vdpa;
-       const struct vdpa_config_ops *ops = vdpa->config;
        u16 num;

-       num = ops->get_vq_num_max(vdpa);
+       /*
+        * VHOST_VDPA_GET_VRING_NUM asssumes a global max virtqueue