2 files changed, 66 insertions, 0 deletions

diff --git a/tests/libqos/virtio.c b/tests/libqos/virtio.c
index ec30cb99b2..9880a6964e 100644
--- a/tests/libqos/virtio.c
+++ b/tests/libqos/virtio.c
@@ -116,6 +116,35 @@ uint8_t qvirtio_wait_status_byte_no_isr(QVirtioDevice *d,
     return val;
 }
 
+/*
+ * qvirtio_wait_used_elem:
+ * @desc_idx: The next expected vq->desc[] index in the used ring
+ * @timeout_us: How many microseconds to wait before failing
+ *
+ * This function waits for the next completed request on the used ring.
+ */
+void qvirtio_wait_used_elem(QVirtioDevice *d,
+                            QVirtQueue *vq,
+                            uint32_t desc_idx,
+                            gint64 timeout_us)
+{
+    gint64 start_time = g_get_monotonic_time();
+
+    for (;;) {
+        uint32_t got_desc_idx;
+
+        clock_step(100);
+
+        if (d->bus->get_queue_isr_status(d, vq) &&
+            qvirtqueue_get_buf(vq, &got_desc_idx)) {
+            g_assert_cmpint(got_desc_idx, ==, desc_idx);
+            return;
+        }
+
+        g_assert(g_get_monotonic_time() - start_time <= timeout_us);
+    }
+}
+
 void qvirtio_wait_config_isr(QVirtioDevice *d, gint64 timeout_us)
 {
     gint64 start_time = g_get_monotonic_time();
@@ -272,6 +301,37 @@ void qvirtqueue_kick(QVirtioDevice *d, QVirtQueue *vq, uint32_t free_head)
     }
 }
 
+/*
+ * qvirtqueue_get_buf:
+ * @desc_idx: A pointer that is filled with the vq->desc[] index, may be NULL
+ *
+ * This function gets the next used element if there is one ready.
+ *
+ * Returns: true if an element was ready, false otherwise
+ */
+bool qvirtqueue_get_buf(QVirtQueue *vq, uint32_t *desc_idx)
+{
+    uint16_t idx;
+
+    idx = readw(vq->used + offsetof(struct vring_used, idx));
+    if (idx == vq->last_used_idx) {
+        return false;
+    }
+
+    if (desc_idx) {
+        uint64_t elem_addr;
+
+        elem_addr = vq->used +
+                    offsetof(struct vring_used, ring) +
+                    (vq->last_used_idx % vq->size) *
+                    sizeof(struct vring_used_elem);
+        *desc_idx = readl(elem_addr + offsetof(struct vring_used_elem, id));
+    }
+
+    vq->last_used_idx++;
+    return true;
+}
+
 void qvirtqueue_set_used_event(QVirtQueue *vq, uint16_t idx)
 {
     g_assert(vq->event);
diff --git a/tests/libqos/virtio.h b/tests/libqos/virtio.h
index 829de5eb35..8fbcd1869c 100644
--- a/tests/libqos/virtio.h
+++ b/tests/libqos/virtio.h
@@ -32,6 +32,7 @@ typedef struct QVirtQueue {
     uint32_t free_head;
     uint32_t num_free;
     uint32_t align;
+    uint16_t last_used_idx;
     bool indirect;
     bool event;
 } QVirtQueue;
@@ -120,6 +121,10 @@ uint8_t qvirtio_wait_status_byte_no_isr(QVirtioDevice *d,
                                         QVirtQueue *vq,
                                         uint64_t addr,
                                         gint64 timeout_us);
+void qvirtio_wait_used_elem(QVirtioDevice *d,
+                            QVirtQueue *vq,
+                            uint32_t desc_idx,
+                            gint64 timeout_us);
 void qvirtio_wait_config_isr(QVirtioDevice *d, gint64 timeout_us);
 QVirtQueue *qvirtqueue_setup(QVirtioDevice *d,
                              QGuestAllocator *alloc, uint16_t index);
@@ -135,6 +140,7 @@ uint32_t qvirtqueue_add(QVirtQueue *vq, uint64_t data, uint32_t len, bool write,
                                                                     bool next);
 uint32_t qvirtqueue_add_indirect(QVirtQueue *vq, QVRingIndirectDesc *indirect);
 void qvirtqueue_kick(QVirtioDevice *d, QVirtQueue *vq, uint32_t free_head);
+bool qvirtqueue_get_buf(QVirtQueue *vq, uint32_t *desc_idx);
 
 void qvirtqueue_set_used_event(QVirtQueue *vq, uint16_t idx);
 #endif