[PATCH 2/7] vhost: move svq next desc array to descs state struct

["Eugenio Pérez" <eperezma@redhat.com>]

It's the right place for it as it is part of the descriptor state.  We
save the memory management of the array, and make the code changes of
the next patches easier.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/vhost-shadow-virtqueue.c | 14 ++++++--------
 hw/virtio/vhost-shadow-virtqueue.h | 12 ++++++------
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index 6242aeb69c1a..901253d06e50 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -175,7 +175,7 @@ static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
     for (n = 0; n < num; n++) {
         if (more_descs || (n + 1 < num)) {
             descs[i].flags = flags | cpu_to_le16(VRING_DESC_F_NEXT);
-            descs[i].next = cpu_to_le16(svq->desc_next[i]);
+            descs[i].next = cpu_to_le16(svq->desc_state[i].next);
         } else {
             descs[i].flags = flags;
         }
@@ -183,10 +183,10 @@ static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
         descs[i].len = cpu_to_le32(iovec[n].iov_len);
 
         last = i;
-        i = svq->desc_next[i];
+        i = svq->desc_state[i].next;
     }
 
-    svq->free_head = svq->desc_next[last];
+    svq->free_head = svq->desc_state[last].next;
     return true;
 }
 
@@ -432,7 +432,7 @@ static uint16_t vhost_svq_last_desc_of_chain(const VhostShadowVirtqueue *svq,
                                              uint16_t num, uint16_t i)
 {
     for (uint16_t j = 0; j < (num - 1); ++j) {
-        i = svq->desc_next[i];
+        i = svq->desc_state[i].next;
     }
 
     return i;
@@ -473,7 +473,7 @@ static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
     num = svq->desc_state[used_elem.id].ndescs;
     svq->desc_state[used_elem.id].ndescs = 0;
     last_used_chain = vhost_svq_last_desc_of_chain(svq, num, used_elem.id);
-    svq->desc_next[last_used_chain] = svq->free_head;
+    svq->desc_state[last_used_chain].next = svq->free_head;
     svq->free_head = used_elem.id;
     svq->num_free += num;
 
@@ -705,9 +705,8 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
                            PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS,
                            -1, 0);
     svq->desc_state = g_new0(SVQDescState, svq->vring.num);
-    svq->desc_next = g_new0(uint16_t, svq->vring.num);
     for (unsigned i = 0; i < svq->vring.num - 1; i++) {
-        svq->desc_next[i] = i + 1;
+        svq->desc_state[i].next = i + 1;
     }
 }
 
@@ -744,7 +743,6 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq)
         virtqueue_unpop(svq->vq, next_avail_elem, 0);
     }
     svq->vq = NULL;
-    g_free(svq->desc_next);
     g_free(svq->desc_state);
     munmap(svq->vring.desc, vhost_svq_driver_area_size(svq));
     munmap(svq->vring.used, vhost_svq_device_area_size(svq));
diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
index 9c273739d6df..f52c33e65046 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -23,6 +23,12 @@ typedef struct SVQDescState {
      * guest's
      */
     unsigned int ndescs;
+
+    /*
+     * Backup next field for each descriptor so we can recover securely, not
+     * needing to trust the device access.
+     */
+    uint16_t next;
 } SVQDescState;
 
 typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
@@ -84,12 +90,6 @@ typedef struct VhostShadowVirtqueue {
     /* Next VirtQueue element that guest made available */
     VirtQueueElement *next_guest_avail_elem;
 
-    /*
-     * Backup next field for each descriptor so we can recover securely, not
-     * needing to trust the device access.
-     */
-    uint16_t *desc_next;
-
     /* Caller callbacks */
     const VhostShadowVirtqueueOps *ops;
 
-- 
2.53.0