[PULL 33/41] vdpa: Fix endian bugs in shadow virtqueue

["Michael S. Tsirkin" <mst@redhat.com>]

From: Konstantin Shkolnyy <kshk@linux.ibm.com>

VDPA didn't work on a big-endian machine due to missing/incorrect
CPU<->LE data format conversions.

Signed-off-by: Konstantin Shkolnyy <kshk@linux.ibm.com>
Message-Id: <20250212164923.1971538-1-kshk@linux.ibm.com>
Fixes: 10857ec0ad ("vhost: Add VhostShadowVirtqueue")
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/vhost-shadow-virtqueue.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index 30ba565f03..2481d49345 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -182,10 +182,10 @@ static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
         descs[i].len = cpu_to_le32(iovec[n].iov_len);
 
         last = i;
-        i = cpu_to_le16(svq->desc_next[i]);
+        i = svq->desc_next[i];
     }
 
-    svq->free_head = le16_to_cpu(svq->desc_next[last]);
+    svq->free_head = svq->desc_next[last];
     return true;
 }
 
@@ -247,10 +247,12 @@ static void vhost_svq_kick(VhostShadowVirtqueue *svq)
     smp_mb();
 
     if (virtio_vdev_has_feature(svq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
-        uint16_t avail_event = *(uint16_t *)(&svq->vring.used->ring[svq->vring.num]);
+        uint16_t avail_event = le16_to_cpu(
+                *(uint16_t *)(&svq->vring.used->ring[svq->vring.num]));
         needs_kick = vring_need_event(avail_event, svq->shadow_avail_idx, svq->shadow_avail_idx - 1);
     } else {
-        needs_kick = !(svq->vring.used->flags & VRING_USED_F_NO_NOTIFY);
+        needs_kick =
+                !(svq->vring.used->flags & cpu_to_le16(VRING_USED_F_NO_NOTIFY));
     }
 
     if (!needs_kick) {
@@ -386,7 +388,7 @@ static bool vhost_svq_more_used(VhostShadowVirtqueue *svq)
         return true;
     }
 
-    svq->shadow_used_idx = cpu_to_le16(*(volatile uint16_t *)used_idx);
+    svq->shadow_used_idx = le16_to_cpu(*(volatile uint16_t *)used_idx);
 
     return svq->last_used_idx != svq->shadow_used_idx;
 }
@@ -404,7 +406,7 @@ static bool vhost_svq_enable_notification(VhostShadowVirtqueue *svq)
 {
     if (virtio_vdev_has_feature(svq->vdev, VIRTIO_RING_F_EVENT_IDX)) {
         uint16_t *used_event = (uint16_t *)&svq->vring.avail->ring[svq->vring.num];
-        *used_event = svq->shadow_used_idx;
+        *used_event = cpu_to_le16(svq->shadow_used_idx);
     } else {
         svq->vring.avail->flags &= ~cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
     }
@@ -429,7 +431,7 @@ 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 = le16_to_cpu(svq->desc_next[i]);
+        i = svq->desc_next[i];
     }
 
     return i;
@@ -704,7 +706,7 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
     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] = cpu_to_le16(i + 1);
+        svq->desc_next[i] = i + 1;
     }
 }
 
-- 
MST