[dpdk-dev] [PATCH v4 3/3] vhost: access VhostUsrMsg via packed struct

[Dariusz Stojaczyk]

From: Daniel Verkamp <daniel.verkamp at intel.com>

Accessing fields of a packed struct through unaligned pointers is
undefined behavior. Instead of passing pointers to particular fields,
a pointer to the root struct should be used. This patch does exactly
that.

Signed-off-by: Daniel Verkamp <daniel.verkamp at intel.com>
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk at intel.com>
---
v4: updated commit message
v3: fix checkpatch warnings
v2: remove gerrit id
 lib/librte_vhost/vhost_user.c | 60 +++++++++++++++++++++++--------------------
 1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 2cc0b66..ab2f40a 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -197,11 +197,11 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t features)
  */
 static int
 vhost_user_set_vring_num(struct virtio_net *dev,
-			 struct vhost_vring_state *state)
+			 VhostUserMsg *msg)
 {
-	struct vhost_virtqueue *vq = dev->virtqueue[state->index];
+	struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];
 
-	vq->size = state->num;
+	vq->size = msg->payload.state.num;
 
 	if (dev->dequeue_zero_copy) {
 		vq->nr_zmbuf = 0;
@@ -334,7 +334,7 @@ qva_to_vva(struct virtio_net *dev, uint64_t qva)
  * This function then converts these to our address space.
  */
 static int
-vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
+vhost_user_set_vring_addr(struct virtio_net *dev, VhostUserMsg *msg)
 {
 	struct vhost_virtqueue *vq;
 
@@ -342,11 +342,11 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
 		return -1;
 
 	/* addr->index refers to the queue index. The txq 1, rxq is 0. */
-	vq = dev->virtqueue[addr->index];
+	vq = dev->virtqueue[msg->payload.addr.index];
 
 	/* The addresses are converted from QEMU virtual to Vhost virtual. */
 	vq->desc = (struct vring_desc *)(uintptr_t)qva_to_vva(dev,
-			addr->desc_user_addr);
+			msg->payload.addr.desc_user_addr);
 	if (vq->desc == 0) {
 		RTE_LOG(ERR, VHOST_CONFIG,
 			"(%d) failed to find desc ring address.\n",
@@ -354,11 +354,11 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
 		return -1;
 	}
 
-	dev = numa_realloc(dev, addr->index);
-	vq = dev->virtqueue[addr->index];
+	dev = numa_realloc(dev, msg->payload.addr.index);
+	vq = dev->virtqueue[msg->payload.addr.index];
 
 	vq->avail = (struct vring_avail *)(uintptr_t)qva_to_vva(dev,
-			addr->avail_user_addr);
+			msg->payload.addr.avail_user_addr);
 	if (vq->avail == 0) {
 		RTE_LOG(ERR, VHOST_CONFIG,
 			"(%d) failed to find avail ring address.\n",
@@ -367,7 +367,7 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
 	}
 
 	vq->used = (struct vring_used *)(uintptr_t)qva_to_vva(dev,
-			addr->used_user_addr);
+			msg->payload.addr.used_user_addr);
 	if (vq->used == 0) {
 		RTE_LOG(ERR, VHOST_CONFIG,
 			"(%d) failed to find used ring address.\n",
@@ -384,7 +384,7 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
 		vq->last_avail_idx = vq->used->idx;
 	}
 
-	vq->log_guest_addr = addr->log_guest_addr;
+	vq->log_guest_addr = msg->payload.addr.log_guest_addr;
 
 	LOG_DEBUG(VHOST_CONFIG, "(%d) mapped address desc: %p\n",
 			dev->vid, vq->desc);
@@ -403,10 +403,12 @@ vhost_user_set_vring_addr(struct virtio_net *dev, struct vhost_vring_addr *addr)
  */
 static int
 vhost_user_set_vring_base(struct virtio_net *dev,
-			  struct vhost_vring_state *state)
+			  VhostUserMsg *msg)
 {
-	dev->virtqueue[state->index]->last_used_idx  = state->num;
-	dev->virtqueue[state->index]->last_avail_idx = state->num;
+	dev->virtqueue[msg->payload.state.index]->last_used_idx  =
+			msg->payload.state.num;
+	dev->virtqueue[msg->payload.state.index]->last_avail_idx =
+			msg->payload.state.num;
 
 	return 0;
 }
@@ -697,9 +699,9 @@ free_zmbufs(struct vhost_virtqueue *vq)
  */
 static int
 vhost_user_get_vring_base(struct virtio_net *dev,
-			  struct vhost_vring_state *state)
+			  VhostUserMsg *msg)
 {
-	struct vhost_virtqueue *vq = dev->virtqueue[state->index];
+	struct vhost_virtqueue *vq = dev->virtqueue[msg->payload.state.index];
 
 	/* We have to stop the queue (virtio) if it is running. */
 	if (dev->flags & VIRTIO_DEV_RUNNING) {
@@ -710,10 +712,11 @@ vhost_user_get_vring_base(struct virtio_net *dev,
 	dev->flags &= ~VIRTIO_DEV_READY;
 
 	/* Here we are safe to get the last used index */
-	state->num = vq->last_used_idx;
+	msg->payload.state.num = vq->last_used_idx;
 
 	RTE_LOG(INFO, VHOST_CONFIG,
-		"vring base idx:%d file:%d\n", state->index, state->num);
+		"vring base idx:%d file:%d\n", msg->payload.state.index,
+		msg->payload.state.num);
 	/*
 	 * Based on current qemu vhost-user implementation, this message is
 	 * sent and only sent in vhost_vring_stop.
@@ -738,18 +741,19 @@ vhost_user_get_vring_base(struct virtio_net *dev,
  */
 static int
 vhost_user_set_vring_enable(struct virtio_net *dev,
-			    struct vhost_vring_state *state)
+			    VhostUserMsg *msg)
 {
-	int enable = (int)state->num;
+	int enable = (int)msg->payload.state.num;
 
 	RTE_LOG(INFO, VHOST_CONFIG,
 		"set queue enable: %d to qp idx: %d\n",
-		enable, state->index);
+		enable, msg->payload.state.index);
 
 	if (dev->notify_ops->vring_state_changed)
-		dev->notify_ops->vring_state_changed(dev->vid, state->index, enable);
+		dev->notify_ops->vring_state_changed(dev->vid,
+				msg->payload.state.index, enable);
 
-	dev->virtqueue[state->index]->enabled = enable;
+	dev->virtqueue[msg->payload.state.index]->enabled = enable;
 
 	return 0;
 }
@@ -1038,17 +1042,17 @@ vhost_user_msg_handler(int vid, int fd)
 		break;
 
 	case VHOST_USER_SET_VRING_NUM:
-		vhost_user_set_vring_num(dev, &msg.payload.state);
+		vhost_user_set_vring_num(dev, &msg);
 		break;
 	case VHOST_USER_SET_VRING_ADDR:
-		vhost_user_set_vring_addr(dev, &msg.payload.addr);
+		vhost_user_set_vring_addr(dev, &msg);
 		break;
 	case VHOST_USER_SET_VRING_BASE:
-		vhost_user_set_vring_base(dev, &msg.payload.state);
+		vhost_user_set_vring_base(dev, &msg);
 		break;
 
 	case VHOST_USER_GET_VRING_BASE:
-		vhost_user_get_vring_base(dev, &msg.payload.state);
+		vhost_user_get_vring_base(dev, &msg);
 		msg.size = sizeof(msg.payload.state);
 		send_vhost_message(fd, &msg);
 		break;
@@ -1073,7 +1077,7 @@ vhost_user_msg_handler(int vid, int fd)
 		break;
 
 	case VHOST_USER_SET_VRING_ENABLE:
-		vhost_user_set_vring_enable(dev, &msg.payload.state);
+		vhost_user_set_vring_enable(dev, &msg);
 		break;
 	case VHOST_USER_SEND_RARP:
 		vhost_user_send_rarp(dev, &msg);
-- 
2.7.4