Re: [PATCH v5 06/10] vdpa: Make vhost_vdpa_net_cvq_map_elem accept any out sg

[Jason Wang]

在 2022/8/3 01:57, Eugenio Pérez 写道:
So its generic enough to accept any out sg buffer and we can inject
NIC state messages.

Signed-off-by: Eugenio Pérez <epere...@redhat.com>
---
v5: Accept out sg instead of dev_buffers[]
---
  net/vhost-vdpa.c | 13 +++++++------
  1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 33bf3d6409..2421bca347 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -302,16 +302,16 @@ dma_map_err:
  }
  
  /**
- * Copy the guest element into a dedicated buffer suitable to be sent to NIC
+ * Maps out sg and in buffer into dedicated buffers suitable to be sent to NIC
   */
-static bool vhost_vdpa_net_cvq_map_elem(VhostVDPAState *s,
-                                        VirtQueueElement *elem,
-                                        size_t *out_len)
+static bool vhost_vdpa_net_cvq_map_sg(VhostVDPAState *s,
+                                      const struct iovec *out, size_t out_num,
+                                      size_t *out_len)


This still looks not genreal as there's no guarantee that we won't have 
command-in-specific-data. One example is that Ali is working on the 
virtio-net statistics fetching from the control virtqueue.

So it looks to me we'd better have a general bounce_map here that accepts:

1) out_sg and out_num
2) in_sg and in_num

In this level, we'd better not have any special care about the in as the 
ack. And we need do bouncing:

1) for out buffer, during map
2) for in buffer during unmap

Thanks


  {
      size_t in_copied;
      bool ok;
  
-    ok = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, elem->out_sg, elem->out_num,
+    ok = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, out, out_num,
                                  vhost_vdpa_net_cvq_cmd_len(),
                                  s->cvq_cmd_out_buffer, out_len, false);
      if (unlikely(!ok)) {
@@ -435,7 +435,8 @@ static int 
vhost_vdpa_net_handle_ctrl_avail(VhostShadowVirtqueue *svq,
      };
      bool ok;
  
-    ok = vhost_vdpa_net_cvq_map_elem(s, elem, &dev_buffers[0].iov_len);
+    ok = vhost_vdpa_net_cvq_map_sg(s, elem->out_sg, elem->out_num,
+                                   &dev_buffers[0].iov_len);
      if (unlikely(!ok)) {
          goto out;
      }