vdpa_sim: make 'config' generic and usable for any device type

Add new 'config_size' attribute in 'vdpasim_dev_attr' and allocates
'config' dynamically to support any device types.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20201215144256.155342-12-sgarzare@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -70,6 +70,7 @@ struct vdpasim_virtqueue {
 
 struct vdpasim_dev_attr {
 	u64 supported_features;
+	size_t config_size;
 	int nvqs;
 	u32 id;
 
@@ -84,7 +85,8 @@ struct vdpasim {
 	struct vdpasim_dev_attr dev_attr;
 	/* spinlock to synchronize virtqueue state */
 	spinlock_t lock;
-	struct virtio_net_config config;
+	/* virtio config according to device type */
+	void *config;
 	struct vhost_iotlb *iommu;
 	void *buffer;
 	u32 status;
@@ -384,6 +386,10 @@ static struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr)
 		goto err_iommu;
 	set_dma_ops(dev, &vdpasim_dma_ops);
 
+	vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
+	if (!vdpasim->config)
+		goto err_iommu;
+
 	vdpasim->vqs = kcalloc(dev_attr->nvqs, sizeof(struct vdpasim_virtqueue),
 			       GFP_KERNEL);
 	if (!vdpasim->vqs)
@@ -524,7 +530,8 @@ 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 = &vdpasim->config;
+	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)))
@@ -596,8 +603,8 @@ static void vdpasim_get_config(struct vdpa_device *vdpa, unsigned int offset,
 {
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
-	if (offset + len < sizeof(struct virtio_net_config))
-		memcpy(buf, (u8 *)&vdpasim->config + offset, len);
+	if (offset + len < vdpasim->dev_attr.config_size)
+		memcpy(buf, vdpasim->config + offset, len);
 }
 
 static void vdpasim_set_config(struct vdpa_device *vdpa, unsigned int offset,
@@ -684,6 +691,7 @@ static void vdpasim_free(struct vdpa_device *vdpa)
 	if (vdpasim->iommu)
 		vhost_iotlb_free(vdpasim->iommu);
 	kfree(vdpasim->vqs);
+	kfree(vdpasim->config);
 }
 
 static const struct vdpa_config_ops vdpasim_config_ops = {
@@ -746,6 +754,7 @@ static int __init vdpasim_dev_init(void)
 	dev_attr.id = VIRTIO_ID_NET;
 	dev_attr.supported_features = VDPASIM_NET_FEATURES;
 	dev_attr.nvqs = VDPASIM_VQ_NUM;
+	dev_attr.config_size = sizeof(struct virtio_net_config);
 	dev_attr.work_fn = vdpasim_net_work;
 
 	vdpasim_dev = vdpasim_create(&dev_attr);