From: Wafer <wafer@jaguarmicro.com>
To: mst@redhat.com
Cc: eperezma@redhat.com, jasowang@redhat.com, qemu-devel@nongnu.org,
angus.chen@jaguarmicro.com, Wafer <wafer@jaguarmicro.com>
Subject: [PATCH] hw/virtio: Fix obtain the buffer id from the last descriptor
Date: Mon, 22 Apr 2024 09:40:41 +0800 [thread overview]
Message-ID: <20240422014041.5706-2-wafer@jaguarmicro.com> (raw)
The virtio-1.3 specification
<https://docs.oasis-open.org/virtio/virtio/v1.3/virtio-v1.3.html> writes:
2.8.6 Next Flag: Descriptor Chaining
Buffer ID is included in the last descriptor in the list.
If the feature (_F_INDIRECT_DESC) has been negotiated, install only
one descriptor in the virtqueue.
Therefor the buffer id should be obtained from the first descriptor.
In descriptor chaining scenarios, the buffer id should be obtained
from the last descriptor.
Fixes: 86044b24e8 ("virtio: basic packed virtqueue support")
Signed-off-by: Wafer <wafer@jaguarmicro.com>
---
hw/virtio/virtio.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 871674f9be..f65d4b4161 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1739,6 +1739,11 @@ static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz)
goto err_undo_map;
}
+ if (desc_cache != &indirect_desc_cache) {
+ /* Buffer ID is included in the last descriptor in the list. */
+ id = desc.id;
+ }
+
rc = virtqueue_packed_read_next_desc(vq, &desc, desc_cache, max, &i,
desc_cache ==
&indirect_desc_cache);
--
2.27.0
next reply other threads:[~2024-04-22 1:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-22 1:40 Wafer [this message]
2024-05-08 4:00 ` [PATCH] hw/virtio: Fix obtain the buffer id from the last descriptor Jason Wang
2024-05-09 4:32 ` Wafer
2024-05-09 5:45 ` Eugenio Perez Martin
2024-05-08 12:56 ` Eugenio Perez Martin
2024-05-08 18:21 ` Michael S. Tsirkin
2024-05-09 2:20 ` Wafer
2024-05-09 5:44 ` Eugenio Perez Martin
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