vdpa_sim: support vendor statistics

This patch adds a new config ops callback to allow individual
simulator to implement the vendor stats callback.
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221223055548.27810-4-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -432,6 +432,18 @@ static int vdpasim_get_vq_state(struct vdpa_device *vdpa, u16 idx,
 	return 0;
 }
 
+static int vdpasim_get_vq_stats(struct vdpa_device *vdpa, u16 idx,
+				struct sk_buff *msg,
+				struct netlink_ext_ack *extack)
+{
+	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+
+	if (vdpasim->dev_attr.get_stats)
+		return vdpasim->dev_attr.get_stats(vdpasim, idx,
+						   msg, extack);
+	return -EOPNOTSUPP;
+}
+
 static u32 vdpasim_get_vq_align(struct vdpa_device *vdpa)
 {
 	return VDPASIM_QUEUE_ALIGN;
@@ -739,6 +751,7 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
 	.set_vq_ready           = vdpasim_set_vq_ready,
 	.get_vq_ready           = vdpasim_get_vq_ready,
 	.set_vq_state           = vdpasim_set_vq_state,
+	.get_vendor_vq_stats    = vdpasim_get_vq_stats,
 	.get_vq_state           = vdpasim_get_vq_state,
 	.get_vq_align           = vdpasim_get_vq_align,
 	.get_vq_group           = vdpasim_get_vq_group,
@@ -773,6 +786,7 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
 	.set_vq_ready           = vdpasim_set_vq_ready,
 	.get_vq_ready           = vdpasim_get_vq_ready,
 	.set_vq_state           = vdpasim_set_vq_state,
+	.get_vendor_vq_stats    = vdpasim_get_vq_stats,
 	.get_vq_state           = vdpasim_get_vq_state,
 	.get_vq_align           = vdpasim_get_vq_align,
 	.get_vq_group           = vdpasim_get_vq_group,

drivers/vdpa/vdpa_sim/vdpa_sim.h

@@ -48,6 +48,9 @@ struct vdpasim_dev_attr {
 	work_func_t work_fn;
 	void (*get_config)(struct vdpasim *vdpasim, void *config);
 	void (*set_config)(struct vdpasim *vdpasim, const void *config);
+	int (*get_stats)(struct vdpasim *vdpasim, u16 idx,
+			 struct sk_buff *msg,
+			 struct netlink_ext_ack *extack);
 };
 
 /* State of each vdpasim device */