vdpa_sim: move buffer allocation in the devices

Currently, the vdpa_sim core does not use the buffer, but only
allocates it.

The buffer is used by devices differently, and some future devices
may not use it. So let's move all its management inside the devices.

Add a new `free` device callback called to clean up the resources
allocated by the device.

Signed-off-by: Stefano Garzarella <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>

drivers/vdpa/vdpa_sim/vdpa_sim.c

···
 	for (i = 0; i < vdpasim->dev_attr.nas; i++)
 		vhost_iotlb_init(&vdpasim->iommu[i], max_iotlb_entries, 0);
 
-	vdpasim->buffer = kvmalloc(dev_attr->buffer_size, GFP_KERNEL);
-	if (!vdpasim->buffer)
-		goto err_iommu;
-
 	for (i = 0; i < dev_attr->nvqs; i++)
 		vringh_set_iotlb(&vdpasim->vqs[i].vring, &vdpasim->iommu[0],
 				 &vdpasim->iommu_lock);
···
 		vringh_kiov_cleanup(&vdpasim->vqs[i].in_iov);
 	}
 
-	kvfree(vdpasim->buffer);
+	vdpasim->dev_attr.free(vdpasim);
+
 	for (i = 0; i < vdpasim->dev_attr.nas; i++)
 		vhost_iotlb_reset(&vdpasim->iommu[i]);
 	kfree(vdpasim->iommu);

drivers/vdpa/vdpa_sim/vdpa_sim.h

···
 	u64 supported_features;
 	size_t alloc_size;
 	size_t config_size;
-	size_t buffer_size;
 	int nvqs;
 	u32 id;
 	u32 ngroups;
···
 	int (*get_stats)(struct vdpasim *vdpasim, u16 idx,
 			 struct sk_buff *msg,
 			 struct netlink_ext_ack *extack);
+	void (*free)(struct vdpasim *vdpasim);
 };
 
 /* State of each vdpasim device */
···
 	void *config;
 	struct vhost_iotlb *iommu;
 	bool *iommu_pt;
-	void *buffer;
 	u32 status;
 	u32 generation;
 	u64 features;

drivers/vdpa/vdpa_sim/vdpa_sim_blk.c

···
 #define VDPASIM_BLK_AS_NUM	1
 #define VDPASIM_BLK_GROUP_NUM	1
 
+struct vdpasim_blk {
+	struct vdpasim vdpasim;
+	void *buffer;
+};
+
+static struct vdpasim_blk *sim_to_blk(struct vdpasim *vdpasim)
+{
+	return container_of(vdpasim, struct vdpasim_blk, vdpasim);
+}
+
 static char vdpasim_blk_id[VIRTIO_BLK_ID_BYTES] = "vdpa_blk_sim";
 
 static bool vdpasim_blk_check_range(struct vdpasim *vdpasim, u64 start_sector,
···
 static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
 				   struct vdpasim_virtqueue *vq)
 {
+	struct vdpasim_blk *blk = sim_to_blk(vdpasim);
 	size_t pushed = 0, to_pull, to_push;
 	struct virtio_blk_outhdr hdr;
 	bool handled = false;
···
 		}
 
 		bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov,
-					      vdpasim->buffer + offset,
-					      to_push);
+					      blk->buffer + offset, to_push);
 		if (bytes < 0) {
 			dev_dbg(&vdpasim->vdpa.dev,
 				"vringh_iov_push_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
···
 		}
 
 		bytes = vringh_iov_pull_iotlb(&vq->vring, &vq->out_iov,
-					      vdpasim->buffer + offset,
-					      to_pull);
+					      blk->buffer + offset, to_pull);
 		if (bytes < 0) {
 			dev_dbg(&vdpasim->vdpa.dev,
 				"vringh_iov_pull_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
···
 		}
 
 		if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
-			memset(vdpasim->buffer + offset, 0,
+			memset(blk->buffer + offset, 0,
 			       num_sectors << SECTOR_SHIFT);
 		}
 
···
 
 }
 
+static void vdpasim_blk_free(struct vdpasim *vdpasim)
+{
+	struct vdpasim_blk *blk = sim_to_blk(vdpasim);
+
+	kvfree(blk->buffer);
+}
+
 static void vdpasim_blk_mgmtdev_release(struct device *dev)
 {
 }
···
 			       const struct vdpa_dev_set_config *config)
 {
 	struct vdpasim_dev_attr dev_attr = {};
+	struct vdpasim_blk *blk;
 	struct vdpasim *simdev;
 	int ret;
 
···
 	dev_attr.nvqs = VDPASIM_BLK_VQ_NUM;
 	dev_attr.ngroups = VDPASIM_BLK_GROUP_NUM;
 	dev_attr.nas = VDPASIM_BLK_AS_NUM;
-	dev_attr.alloc_size = sizeof(struct vdpasim);
+	dev_attr.alloc_size = sizeof(struct vdpasim_blk);
 	dev_attr.config_size = sizeof(struct virtio_blk_config);
 	dev_attr.get_config = vdpasim_blk_get_config;
 	dev_attr.work_fn = vdpasim_blk_work;
-	dev_attr.buffer_size = VDPASIM_BLK_CAPACITY << SECTOR_SHIFT;
+	dev_attr.free = vdpasim_blk_free;
 
 	simdev = vdpasim_create(&dev_attr, config);
 	if (IS_ERR(simdev))
 		return PTR_ERR(simdev);
+
+	blk = sim_to_blk(simdev);
+
+	blk->buffer = kvmalloc(VDPASIM_BLK_CAPACITY << SECTOR_SHIFT,
+			       GFP_KERNEL);
+	if (!blk->buffer) {
+		ret = -ENOMEM;
+		goto put_dev;
+	}
 
 	ret = _vdpa_register_device(&simdev->vdpa, VDPASIM_BLK_VQ_NUM);
 	if (ret)

drivers/vdpa/vdpa_sim/vdpa_sim_net.c

···
 	struct vdpasim_dataq_stats tx_stats;
 	struct vdpasim_dataq_stats rx_stats;
 	struct vdpasim_cq_stats cq_stats;
+	void *buffer;
 };
 
 static struct vdpasim_net *sim_to_net(struct vdpasim *vdpasim)
···
 	size_t hdr_len = modern ? sizeof(struct virtio_net_hdr_v1) :
 				  sizeof(struct virtio_net_hdr);
 	struct virtio_net_config *vio_config = vdpasim->config;
+	struct vdpasim_net *net = sim_to_net(vdpasim);
 
 	if (len < ETH_ALEN + hdr_len)
 		return false;
 
-	if (is_broadcast_ether_addr(vdpasim->buffer + hdr_len) ||
-	    is_multicast_ether_addr(vdpasim->buffer + hdr_len))
+	if (is_broadcast_ether_addr(net->buffer + hdr_len) ||
+	    is_multicast_ether_addr(net->buffer + hdr_len))
 		return true;
-	if (!strncmp(vdpasim->buffer + hdr_len, vio_config->mac, ETH_ALEN))
+	if (!strncmp(net->buffer + hdr_len, vio_config->mac, ETH_ALEN))
 		return true;
 
 	return false;
···
 
 		++tx_pkts;
 		read = vringh_iov_pull_iotlb(&txq->vring, &txq->out_iov,
-					     vdpasim->buffer,
-					     PAGE_SIZE);
+					     net->buffer, PAGE_SIZE);
 
 		tx_bytes += read;
 
···
 		}
 
 		write = vringh_iov_push_iotlb(&rxq->vring, &rxq->in_iov,
-					      vdpasim->buffer, read);
+					      net->buffer, read);
 		if (write <= 0) {
 			++rx_errors;
 			break;
···
 		vio_config->mtu = cpu_to_vdpasim16(vdpasim, 1500);
 }
 
+static void vdpasim_net_free(struct vdpasim *vdpasim)
+{
+	struct vdpasim_net *net = sim_to_net(vdpasim);
+
+	kvfree(net->buffer);
+}
+
 static void vdpasim_net_mgmtdev_release(struct device *dev)
 {
 }
···
 	dev_attr.get_config = vdpasim_net_get_config;
 	dev_attr.work_fn = vdpasim_net_work;
 	dev_attr.get_stats = vdpasim_net_get_stats;
-	dev_attr.buffer_size = PAGE_SIZE;
+	dev_attr.free = vdpasim_net_free;
 
 	simdev = vdpasim_create(&dev_attr, config);
 	if (IS_ERR(simdev))
···
 	u64_stats_init(&net->tx_stats.syncp);
 	u64_stats_init(&net->rx_stats.syncp);
 	u64_stats_init(&net->cq_stats.syncp);
+
+	net->buffer = kvmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!net->buffer) {
+		ret = -ENOMEM;
+		goto reg_err;
+	}
 
 	/*
 	 * Initialization must be completed before this call, since it can