Re: [RFC PATCH v4 17/20] vhost: Use VRING_AVAIL_F_NO_INTERRUPT at device call on shadow virtqueue

[Jason Wang]

在 2021/10/1 下午3:06, Eugenio Pérez 写道:

Signed-off-by: Eugenio Pérez <epere...@redhat.com>

Commit log please.

Thanks

---
  hw/virtio/vhost-shadow-virtqueue.c | 24 +++++++++++++++++++++++-
  1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-shadow-virtqueue.c 
b/hw/virtio/vhost-shadow-virtqueue.c
index 775f8d36a0..2fd0bab75d 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -60,6 +60,9 @@ typedef struct VhostShadowVirtqueue {

/* Next head to consume from device */

      uint16_t used_idx;
+
+    /* Cache for the exposed notification flag */
+    bool notification;
  } VhostShadowVirtqueue;

/* If the device is using some of these, SVQ cannot communicate */

@@ -105,6 +108,24 @@ bool vhost_svq_valid_device_features(uint64_t 
*dev_features)
      return r;
  }

+static void vhost_svq_set_notification(VhostShadowVirtqueue *svq, bool enable)

+{
+    uint16_t notification_flag;
+
+    if (svq->notification == enable) {
+        return;
+    }
+
+    notification_flag = cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT);
+
+    svq->notification = enable;
+    if (enable) {
+        svq->vring.avail->flags &= ~notification_flag;
+    } else {
+        svq->vring.avail->flags |= notification_flag;
+    }
+}
+
  static void vhost_vring_write_descs(VhostShadowVirtqueue *svq,
                                      const struct iovec *iovec,
                                      size_t num, bool more_descs, bool write)
@@ -273,7 +294,7 @@ static void vhost_svq_handle_call_no_test(EventNotifier *n)
      do {
          unsigned i = 0;

- /* TODO: Use VRING_AVAIL_F_NO_INTERRUPT */

+        vhost_svq_set_notification(svq, false);
          while (true) {
              g_autofree VirtQueueElement *elem = vhost_svq_get_buf(svq);
              if (!elem) {
@@ -286,6 +307,7 @@ static void vhost_svq_handle_call_no_test(EventNotifier *n)

virtqueue_flush(vq, i);

          event_notifier_set(&svq->guest_call_notifier);
+        vhost_svq_set_notification(svq, true);
      } while (vhost_svq_more_used(svq));
  }