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Commit 429711ae authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
Browse files

vhost: switch to use new message format 



We use to have message like:

struct vhost_msg {
	int type;
	union {
		struct vhost_iotlb_msg iotlb;
		__u8 padding[64];
	};
};

Unfortunately, there will be a hole of 32bit in 64bit machine because
of the alignment. This leads a different formats between 32bit API and
64bit API. What's more it will break 32bit program running on 64bit
machine.

So fixing this by introducing a new message type with an explicit
32bit reserved field after type like:

struct vhost_msg_v2 {
	__u32 type;
	__u32 reserved;
	union {
		struct vhost_iotlb_msg iotlb;
		__u8 padding[64];
	};
};

We will have a consistent ABI after switching to use this. To enable
this capability, introduce a new ioctl (VHOST_SET_BAKCEND_FEATURE) for
userspace to enable this feature (VHOST_BACKEND_F_IOTLB_V2).

Fixes: 6b1e6cc7 ("vhost: new device IOTLB API")
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9c2e955c

drivers/vhost/net.c

+30 −0
Original line number Diff line number Diff line
@@ -77,6 +77,10 @@ enum { 
			 (1ULL << VIRTIO_F_IOMMU_PLATFORM)

};



enum {

	VHOST_NET_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)

};



enum {

	VHOST_NET_VQ_RX = 0,

	VHOST_NET_VQ_TX = 1,
@@ -1399,6 +1403,21 @@ static long vhost_net_reset_owner(struct vhost_net *n) 
	return err;

}



static int vhost_net_set_backend_features(struct vhost_net *n, u64 features)

{

	int i;



	mutex_lock(&n->dev.mutex);

	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {

		mutex_lock(&n->vqs[i].vq.mutex);

		n->vqs[i].vq.acked_backend_features = features;

		mutex_unlock(&n->vqs[i].vq.mutex);

	}

	mutex_unlock(&n->dev.mutex);



	return 0;

}



static int vhost_net_set_features(struct vhost_net *n, u64 features)

{

	size_t vhost_hlen, sock_hlen, hdr_len;
@@ -1489,6 +1508,17 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl, 
		if (features & ~VHOST_NET_FEATURES)

			return -EOPNOTSUPP;

		return vhost_net_set_features(n, features);

	case VHOST_GET_BACKEND_FEATURES:

		features = VHOST_NET_BACKEND_FEATURES;

		if (copy_to_user(featurep, &features, sizeof(features)))

			return -EFAULT;

		return 0;

	case VHOST_SET_BACKEND_FEATURES:

		if (copy_from_user(&features, featurep, sizeof(features)))

			return -EFAULT;

		if (features & ~VHOST_NET_BACKEND_FEATURES)

			return -EOPNOTSUPP;

		return vhost_net_set_backend_features(n, features);

	case VHOST_RESET_OWNER:

		return vhost_net_reset_owner(n);

	case VHOST_SET_OWNER:

drivers/vhost/vhost.c

+53 −18
Original line number Diff line number Diff line
@@ -315,6 +315,7 @@ static void vhost_vq_reset(struct vhost_dev *dev, 
	vq->log_addr = -1ull;

	vq->private_data = NULL;

	vq->acked_features = 0;

	vq->acked_backend_features = 0;

	vq->log_base = NULL;

	vq->error_ctx = NULL;

	vq->kick = NULL;
@@ -1027,28 +1028,40 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev, 
ssize_t vhost_chr_write_iter(struct vhost_dev *dev,

			     struct iov_iter *from)

{

	struct vhost_msg_node node;

	unsigned size = sizeof(struct vhost_msg);

	size_t ret;

	int err;

	struct vhost_iotlb_msg msg;

	size_t offset;

	int type, ret;



	if (iov_iter_count(from) < size)

		return 0;

	ret = copy_from_iter(&node.msg, size, from);

	if (ret != size)

	ret = copy_from_iter(&type, sizeof(type), from);

	if (ret != sizeof(type))

		goto done;



	switch (node.msg.type) {

	switch (type) {

	case VHOST_IOTLB_MSG:

		err = vhost_process_iotlb_msg(dev, &node.msg.iotlb);

		if (err)

			ret = err;

		/* There maybe a hole after type for V1 message type,

		 * so skip it here.

		 */

		offset = offsetof(struct vhost_msg, iotlb) - sizeof(int);

		break;

	case VHOST_IOTLB_MSG_V2:

		offset = sizeof(__u32);

		break;

	default:

		ret = -EINVAL;

		break;

		goto done;

	}



	iov_iter_advance(from, offset);

	ret = copy_from_iter(&msg, sizeof(msg), from);

	if (ret != sizeof(msg))

		goto done;

	if (vhost_process_iotlb_msg(dev, &msg)) {

		ret = -EFAULT;

		goto done;

	}



	ret = (type == VHOST_IOTLB_MSG) ? sizeof(struct vhost_msg) :

	      sizeof(struct vhost_msg_v2);

done:

	return ret;

}
@@ -1107,13 +1120,28 @@ ssize_t vhost_chr_read_iter(struct vhost_dev *dev, struct iov_iter *to, 
		finish_wait(&dev->wait, &wait);



	if (node) {

		ret = copy_to_iter(&node->msg, size, to);

		struct vhost_iotlb_msg *msg;

		void *start = &node->msg;



		if (ret != size || node->msg.type != VHOST_IOTLB_MISS) {

		switch (node->msg.type) {

		case VHOST_IOTLB_MSG:

			size = sizeof(node->msg);

			msg = &node->msg.iotlb;

			break;

		case VHOST_IOTLB_MSG_V2:

			size = sizeof(node->msg_v2);

			msg = &node->msg_v2.iotlb;

			break;

		default:

			BUG();

			break;

		}



		ret = copy_to_iter(start, size, to);

		if (ret != size || msg->type != VHOST_IOTLB_MISS) {

			kfree(node);

			return ret;

		}



		vhost_enqueue_msg(dev, &dev->pending_list, node);

	}
@@ -1126,12 +1154,19 @@ static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova, int access) 
	struct vhost_dev *dev = vq->dev;

	struct vhost_msg_node *node;

	struct vhost_iotlb_msg *msg;

	bool v2 = vhost_backend_has_feature(vq, VHOST_BACKEND_F_IOTLB_MSG_V2);



	node = vhost_new_msg(vq, VHOST_IOTLB_MISS);

	node = vhost_new_msg(vq, v2 ? VHOST_IOTLB_MSG_V2 : VHOST_IOTLB_MSG);

	if (!node)

		return -ENOMEM;



	if (v2) {

		node->msg_v2.type = VHOST_IOTLB_MSG_V2;

		msg = &node->msg_v2.iotlb;

	} else {

		msg = &node->msg.iotlb;

	}



	msg->type = VHOST_IOTLB_MISS;

	msg->iova = iova;

	msg->perm = access;

drivers/vhost/vhost.h

+10 −1
Original line number Diff line number Diff line
@@ -132,6 +132,7 @@ struct vhost_virtqueue { 
	struct vhost_umem *iotlb;

	void *private_data;

	u64 acked_features;

	u64 acked_backend_features;

	/* Log write descriptors */

	void __user *log_base;

	struct vhost_log *log;
@@ -147,7 +148,10 @@ struct vhost_virtqueue { 
};



struct vhost_msg_node {

  union {

	  struct vhost_msg msg;

	  struct vhost_msg_v2 msg_v2;

  };

  struct vhost_virtqueue *vq;

  struct list_head node;

};
@@ -238,6 +242,11 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit) 
	return vq->acked_features & (1ULL << bit);

}



static inline bool vhost_backend_has_feature(struct vhost_virtqueue *vq, int bit)

{

	return vq->acked_backend_features & (1ULL << bit);

}



#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY

static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)

{

include/uapi/linux/vhost.h

+18 −0
Original line number Diff line number Diff line
@@ -65,6 +65,7 @@ struct vhost_iotlb_msg { 
};



#define VHOST_IOTLB_MSG 0x1

#define VHOST_IOTLB_MSG_V2 0x2



struct vhost_msg {

	int type;
@@ -74,6 +75,15 @@ struct vhost_msg { 
	};

};



struct vhost_msg_v2 {

	__u32 type;

	__u32 reserved;

	union {

		struct vhost_iotlb_msg iotlb;

		__u8 padding[64];

	};

};



struct vhost_memory_region {

	__u64 guest_phys_addr;

	__u64 memory_size; /* bytes */
@@ -160,6 +170,14 @@ struct vhost_memory { 
#define VHOST_GET_VRING_BUSYLOOP_TIMEOUT _IOW(VHOST_VIRTIO, 0x24,	\

					 struct vhost_vring_state)



/* Set or get vhost backend capability */



/* Use message type V2 */

#define VHOST_BACKEND_F_IOTLB_MSG_V2 0x1



#define VHOST_SET_BACKEND_FEATURES _IOW(VHOST_VIRTIO, 0x25, __u64)

#define VHOST_GET_BACKEND_FEATURES _IOW(VHOST_VIRTIO, 0x26, __u64)



/* VHOST_NET specific defines */



/* Attach virtio net ring to a raw socket, or tap device.