From: wafer Xie <[email protected]>

allocated and initialized when creating the vhost-vdpa device,
and release the indirect buffer when vhost-vdpa is stopped.

Signed-off-by: wafer Xie <[email protected]>
---
 hw/virtio/vhost-shadow-virtqueue.c |  25 +++++
 hw/virtio/vhost-vdpa.c             | 163 ++++++++++++++++++++++++++++-
 2 files changed, 187 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-shadow-virtqueue.c 
b/hw/virtio/vhost-shadow-virtqueue.c
index 2481d49345..85eff1d841 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -708,6 +708,25 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, 
VirtIODevice *vdev,
     for (unsigned i = 0; i < svq->vring.num - 1; i++) {
         svq->desc_next[i] = i + 1;
     }
+
+    /* Initialize indirect descriptor state */
+    svq->indirect_enabled = false;
+    svq->current_indirect_buf = -1;
+    for (int i = 0; i < SVQ_NUM_INDIRECT_BUFS; i++) {
+        svq->indirect_bufs[i].desc = NULL;
+        svq->indirect_bufs[i].iova = 0;
+        svq->indirect_bufs[i].size = 0;
+        svq->indirect_bufs[i].state = SVQ_INDIRECT_BUF_FREED;
+        svq->indirect_bufs[i].num_descs = 0;
+        svq->indirect_bufs[i].freed_descs = 0;
+        svq->indirect_bufs[i].freeing_descs = 0;
+        svq->indirect_bufs[i].freed_head = 0;
+    }
+
+    /* Initialize desc_state indirect_buf_idx to -1 */
+    for (unsigned i = 0; i < svq->vring.num; i++) {
+        svq->desc_state[i].indirect_buf_idx = -1;
+    }
 }
 
 /**
@@ -748,6 +767,10 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq)
     munmap(svq->vring.desc, vhost_svq_driver_area_size(svq));
     munmap(svq->vring.used, vhost_svq_device_area_size(svq));
     event_notifier_set_handler(&svq->hdev_call, NULL);
+
+    /* Reset indirect descriptor state (memory is freed by vhost-vdpa) */
+    svq->indirect_enabled = false;
+    svq->current_indirect_buf = -1;
 }
 
 /**
@@ -765,6 +788,8 @@ VhostShadowVirtqueue *vhost_svq_new(const 
VhostShadowVirtqueueOps *ops,
     event_notifier_init_fd(&svq->svq_kick, VHOST_FILE_UNBIND);
     svq->ops = ops;
     svq->ops_opaque = ops_opaque;
+    svq->indirect_enabled = false;
+    svq->current_indirect_buf = -1;
     return svq;
 }
 
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 7061b6e1a3..816868d153 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -584,6 +584,155 @@ static int vhost_vdpa_get_dev_features(struct vhost_dev 
*dev,
     return ret;
 }
 
+/**
+ * Allocate a single indirect descriptor buffer for SVQ
+ *
+ * @v: vhost_vdpa instance
+ * @num_descs: Number of descriptors (should be vring.num)
+ * @buf: Output buffer structure to fill
+ *
+ * Returns true on success, false on failure.
+ */
+static bool vhost_vdpa_alloc_indirect_buf(struct vhost_vdpa *v,
+                                           uint16_t num_descs,
+                                           SVQIndirectDescBuf *buf)
+{
+    size_t desc_size = sizeof(vring_desc_t) * num_descs;
+    size_t alloc_size = ROUND_UP(desc_size, qemu_real_host_page_size());
+    DMAMap needle = {
+        .size = alloc_size - 1,
+        .perm = IOMMU_RO,
+    };
+    vring_desc_t *indirect_desc;
+    int r;
+
+    /* Allocate memory for indirect descriptors */
+    indirect_desc = mmap(NULL, alloc_size, PROT_READ | PROT_WRITE,
+                         MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+    if (indirect_desc == MAP_FAILED) {
+        error_report("Cannot allocate indirect descriptor buffer");
+        return false;
+    }
+
+    /* Allocate IOVA for the indirect descriptor buffer */
+    r = vhost_iova_tree_map_alloc(v->shared->iova_tree, &needle,
+                                  (hwaddr)(uintptr_t)indirect_desc);
+    if (unlikely(r != IOVA_OK)) {
+        error_report("Cannot allocate iova for indirect descriptors (%d)", r);
+        munmap(indirect_desc, alloc_size);
+        return false;
+    }
+
+    /* Map to device */
+    r = vhost_vdpa_dma_map(v->shared, v->address_space_id, needle.iova,
+                           alloc_size, indirect_desc, true);
+    if (unlikely(r != 0)) {
+        error_report("Cannot map indirect descriptors to device: %s (%d)",
+                     g_strerror(-r), -r);
+        vhost_iova_tree_remove(v->shared->iova_tree, needle);
+        munmap(indirect_desc, alloc_size);
+        return false;
+    }
+
+    buf->desc = indirect_desc;
+    buf->iova = needle.iova;
+    buf->size = alloc_size;
+    buf->state = SVQ_INDIRECT_BUF_FREED;
+    buf->num_descs = num_descs;
+    buf->freed_descs = num_descs;  /* All descriptors are free initially */
+    buf->freeing_descs = 0;
+    buf->freed_head = 0;
+
+    return true;
+}
+
+/**
+ * Free a single indirect descriptor buffer
+ *
+ * @v: vhost_vdpa instance
+ * @buf: Buffer to free
+ */
+static void vhost_vdpa_free_indirect_buf(struct vhost_vdpa *v,
+                                          SVQIndirectDescBuf *buf)
+{
+    DMAMap needle;
+    const DMAMap *result;
+    int r;
+
+    if (!buf->desc) {
+        return;
+    }
+
+    needle = (DMAMap) {
+        .translated_addr = (uint64_t)(uintptr_t)buf->desc,
+    };
+    result = vhost_iova_tree_find_iova(v->shared->iova_tree, &needle);
+
+    if (result) {
+        r = vhost_vdpa_dma_unmap(v->shared, v->address_space_id,
+                                 result->iova, buf->size);
+        if (unlikely(r != 0)) {
+            error_report("Cannot unmap indirect descriptors: %s (%d)",
+                         g_strerror(-r), -r);
+        }
+
+        vhost_iova_tree_remove(v->shared->iova_tree, *result);
+    }
+
+    munmap(buf->desc, buf->size);
+    buf->desc = NULL;
+    buf->iova = 0;
+    buf->size = 0;
+}
+
+/**
+ * Initialize indirect descriptor buffers for a single SVQ
+ *
+ * @v: vhost_vdpa instance
+ * @svq: Shadow virtqueue to initialize
+ *
+ * Returns true on success, false on failure.
+ */
+static bool vhost_vdpa_svq_init_indirect(struct vhost_vdpa *v,
+                                          VhostShadowVirtqueue *svq)
+{
+    if (!svq->vring.num) {
+        return true;
+    }
+
+    /* Allocate indirect descriptor buffers for this SVQ */
+    for (int j = 0; j < SVQ_NUM_INDIRECT_BUFS; j++) {
+        if (!vhost_vdpa_alloc_indirect_buf(v, svq->vring.num * 4,
+                                           &svq->indirect_bufs[j])) {
+            /* Cleanup already allocated buffers */
+            for (int k = 0; k < j; k++) {
+                vhost_vdpa_free_indirect_buf(v, &svq->indirect_bufs[k]);
+            }
+            return false;
+        }
+    }
+
+    svq->indirect_enabled = true;
+    svq->current_indirect_buf = 0;
+    return true;
+}
+
+/**
+ * Cleanup indirect descriptor buffers for a single SVQ
+ *
+ * @v: vhost_vdpa instance
+ * @svq: Shadow virtqueue to cleanup
+ */
+static void vhost_vdpa_svq_cleanup_indirect(struct vhost_vdpa *v,
+                                             VhostShadowVirtqueue *svq)
+{
+    for (int j = 0; j < SVQ_NUM_INDIRECT_BUFS; j++) {
+        vhost_vdpa_free_indirect_buf(v, &svq->indirect_bufs[j]);
+    }
+    svq->indirect_enabled = false;
+    svq->current_indirect_buf = -1;
+}
+
 static void vhost_vdpa_init_svq(struct vhost_dev *hdev, struct vhost_vdpa *v)
 {
     g_autoptr(GPtrArray) shadow_vqs = NULL;
@@ -791,8 +940,11 @@ static void vhost_vdpa_svq_cleanup(struct vhost_dev *dev)
     size_t idx;
 
     for (idx = 0; idx < v->shadow_vqs->len; ++idx) {
-        vhost_svq_stop(g_ptr_array_index(v->shadow_vqs, idx));
+        VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, idx);
+        vhost_vdpa_svq_cleanup_indirect(v, svq);
+        vhost_svq_stop(svq);
     }
+
     g_ptr_array_free(v->shadow_vqs, true);
 }
 
@@ -1299,6 +1451,13 @@ static bool vhost_vdpa_svqs_start(struct vhost_dev *dev)
             error_setg_errno(&err, -r, "Cannot set device address");
             goto err_set_addr;
         }
+
+        /* Initialize indirect descriptor buffers for this SVQ */
+        if (!vhost_vdpa_svq_init_indirect(v, svq)) {
+            /* Non-fatal: will fallback to chain mode */
+            warn_report("Cannot initialize indirect descriptor for SVQ %u",
+                virtio_get_queue_index(vq));
+        }
     }
 
     return true;
@@ -1313,6 +1472,7 @@ err:
     error_reportf_err(err, "Cannot setup SVQ %u: ", i);
     for (unsigned j = 0; j < i; ++j) {
         VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, j);
+        vhost_vdpa_svq_cleanup_indirect(v, svq);
         vhost_vdpa_svq_unmap_rings(dev, svq);
         vhost_svq_stop(svq);
     }
@@ -1331,6 +1491,7 @@ static void vhost_vdpa_svqs_stop(struct vhost_dev *dev)
     for (unsigned i = 0; i < v->shadow_vqs->len; ++i) {
         VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, i);
 
+        vhost_vdpa_svq_cleanup_indirect(v, svq);
         vhost_svq_stop(svq);
         vhost_vdpa_svq_unmap_rings(dev, svq);
 
-- 
2.48.1


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