The get_config callback can be used by the device to fill the
config structure.
The callback will be invoked in vdpasim_get_config() before copying
bytes into caller buffer.

Move vDPA-net config updates from vdpasim_set_features() in the
new vdpasim_net_get_config() callback.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
v3:
- checked if get_config callback is set before call it
---
  drivers/vdpa/vdpa_sim/vdpa_sim.c | 35 +++++++++++++++++++-------------
  1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index fe71ed7890e1..f935ade0806b 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -60,6 +60,8 @@ struct vdpasim_virtqueue {
  #define VDPASIM_NET_FEATURES	(VDPASIM_FEATURES | \
  				 (1ULL << VIRTIO_NET_F_MAC))
  
+struct vdpasim;
+
  struct vdpasim_dev_attr {
  	u64 supported_features;
  	size_t config_size;

@@ -67,6 +69,7 @@ struct vdpasim_dev_attr {
  	u32 id;
  
  	work_func_t work_fn;
+	void (*get_config)(struct vdpasim *vdpasim, void *config);
  };
  
  /* State of each vdpasim device */

@@ -522,8 +525,6 @@ static u64 vdpasim_get_features(struct vdpa_device *vdpa)
  static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features)
  {
  	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
-	struct virtio_net_config *config =
-		(struct virtio_net_config *)vdpasim->config;
  
  	/* DMA mapping must be done by driver */
  	if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)))

@@ -531,16 +532,6 @@ static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features)
  
  	vdpasim->features = features & vdpasim->dev_attr.supported_features;
  
-	/* We generally only know whether guest is using the legacy interface
-	 * here, so generally that's the earliest we can set config fields.
-	 * Note: We actually require VIRTIO_F_ACCESS_PLATFORM above which
-	 * implies VIRTIO_F_VERSION_1, but let's not try to be clever here.
-	 */
-
-	config->mtu = cpu_to_vdpasim16(vdpasim, 1500);
-	config->status = cpu_to_vdpasim16(vdpasim, VIRTIO_NET_S_LINK_UP);
-	memcpy(config->mac, macaddr_buf, ETH_ALEN);

-
  	return 0;
  }
  

@@ -595,8 +586,13 @@ static void vdpasim_get_config(struct vdpa_device *vdpa, unsigned int offset,
  {
  	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
  
-	if (offset + len < vdpasim->dev_attr.config_size)
-		memcpy(buf, vdpasim->config + offset, len);
+	if (offset + len > vdpasim->dev_attr.config_size)
+		return;
+
+	if (vdpasim->dev_attr.get_config)
+		vdpasim->dev_attr.get_config(vdpasim, vdpasim->config);
+
+	memcpy(buf, vdpasim->config + offset, len);
  }
  
  static void vdpasim_set_config(struct vdpa_device *vdpa, unsigned int offset,

@@ -739,6 +735,16 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
  	.free                   = vdpasim_free,
  };
  
+static void vdpasim_net_get_config(struct vdpasim *vdpasim, void *config)
+{
+	struct virtio_net_config *net_config =
+		(struct virtio_net_config *)config;
+
+	net_config->mtu = cpu_to_vdpasim16(vdpasim, 1500);
+	net_config->status = cpu_to_vdpasim16(vdpasim, VIRTIO_NET_S_LINK_UP);
+	memcpy(net_config->mac, macaddr_buf, ETH_ALEN);
+}
+
  static int __init vdpasim_dev_init(void)
  {
  	struct vdpasim_dev_attr dev_attr = {};

@@ -747,6 +753,7 @@ static int __init vdpasim_dev_init(void)
  	dev_attr.supported_features = VDPASIM_NET_FEATURES;
  	dev_attr.nvqs = VDPASIM_VQ_NUM;
  	dev_attr.config_size = sizeof(struct virtio_net_config);
+	dev_attr.get_config = vdpasim_net_get_config;
  	dev_attr.work_fn = vdpasim_net_work;
  
  	vdpasim_dev = vdpasim_create(&dev_attr);