From 33abfea239592a706e98269b01c0096249612ea4 Mon Sep 17 00:00:00 2001 From: Wafer Date: Fri, 10 May 2024 15:27:53 +0800 Subject: [PATCH] hw/virtio: Fix obtain the buffer id from the last descriptor MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The virtio-1.3 specification 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 Reviewed-by: Jason Wang Reviewed-by: Eugenio Pérez Acked-by: Jason Wang Message-Id: <20240510072753.26158-2-wafer@jaguarmicro.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 28cd406e16..3678ec2f88 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -1745,6 +1745,11 @@ static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz) &indirect_desc_cache); } while (rc == VIRTQUEUE_READ_DESC_MORE); + if (desc_cache != &indirect_desc_cache) { + /* Buffer ID is included in the last descriptor in the list. */ + id = desc.id; + } + /* Now copy what we have collected and mapped */ elem = virtqueue_alloc_element(sz, out_num, in_num); for (i = 0; i < out_num; i++) {