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[PATCH v2 12/19] vhost: add vhost_svq_poll
From: |
Eugenio Pérez |
Subject: |
[PATCH v2 12/19] vhost: add vhost_svq_poll |
Date: |
Thu, 14 Jul 2022 18:31:43 +0200 |
It allows the Shadow Control VirtQueue to wait for the device to use the
available buffers.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
hw/virtio/vhost-shadow-virtqueue.h | 1 +
hw/virtio/vhost-shadow-virtqueue.c | 22 ++++++++++++++++++++++
2 files changed, 23 insertions(+)
diff --git a/hw/virtio/vhost-shadow-virtqueue.h
b/hw/virtio/vhost-shadow-virtqueue.h
index 1692541cbb..b5c6e3b3b4 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -89,6 +89,7 @@ void vhost_svq_push_elem(VhostShadowVirtqueue *svq, const
SVQElement *elem,
int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg,
size_t out_num, const struct iovec *in_sg, size_t in_num,
SVQElement *elem);
+size_t vhost_svq_poll(VhostShadowVirtqueue *svq);
void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd);
diff --git a/hw/virtio/vhost-shadow-virtqueue.c
b/hw/virtio/vhost-shadow-virtqueue.c
index 5244896358..31a267f721 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -486,6 +486,28 @@ static void vhost_svq_flush(VhostShadowVirtqueue *svq,
} while (!vhost_svq_enable_notification(svq));
}
+/**
+ * Poll the SVQ for one device used buffer.
+ *
+ * This function race with main event loop SVQ polling, so extra
+ * synchronization is needed.
+ *
+ * Return the length written by the device.
+ */
+size_t vhost_svq_poll(VhostShadowVirtqueue *svq)
+{
+ do {
+ uint32_t len;
+ SVQElement *elem = vhost_svq_get_buf(svq, &len);
+ if (elem) {
+ return len;
+ }
+
+ /* Make sure we read new used_idx */
+ smp_rmb();
+ } while (true);
+}
+
/**
* Forward used buffers.
*
--
2.31.1
- [PATCH v2 01/19] vhost: move descriptor translation to vhost_svq_vring_write_descs, (continued)
- [PATCH v2 01/19] vhost: move descriptor translation to vhost_svq_vring_write_descs, Eugenio Pérez, 2022/07/14
- [PATCH v2 02/19] virtio-net: Expose MAC_TABLE_ENTRIES, Eugenio Pérez, 2022/07/14
- [PATCH v2 03/19] virtio-net: Expose ctrl virtqueue logic, Eugenio Pérez, 2022/07/14
- [PATCH v2 07/19] vhost: Decouple vhost_svq_add from VirtQueueElement, Eugenio Pérez, 2022/07/14
- [PATCH v2 08/19] vhost: Add SVQElement, Eugenio Pérez, 2022/07/14
- [PATCH v2 06/19] vhost: Check for queue full at vhost_svq_add, Eugenio Pérez, 2022/07/14
- [PATCH v2 09/19] vhost: Track number of descs in SVQElement, Eugenio Pérez, 2022/07/14
- [PATCH v2 05/19] vhost: Move vhost_svq_kick call to vhost_svq_add, Eugenio Pérez, 2022/07/14
- [PATCH v2 12/19] vhost: add vhost_svq_poll,
Eugenio Pérez <=
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Jason Wang, 2022/07/14
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Eugenio Perez Martin, 2022/07/15
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Jason Wang, 2022/07/15
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Eugenio Perez Martin, 2022/07/15
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Jason Wang, 2022/07/19
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Eugenio Perez Martin, 2022/07/19
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Jason Wang, 2022/07/19
- Re: [PATCH v2 12/19] vhost: add vhost_svq_poll, Eugenio Perez Martin, 2022/07/19
[PATCH v2 13/19] vhost: Add svq avail_handler callback, Eugenio Pérez, 2022/07/14
[PATCH v2 14/19] vdpa: Export vhost_vdpa_dma_map and unmap calls, Eugenio Pérez, 2022/07/14