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Tsirkin" To: qemu-devel@nongnu.org Cc: Peter Maydell , Wafer , Jason Wang , Eugenio =?utf-8?b?UMOpcmV6?= Subject: [PULL 12/46] hw/virtio: Fix obtain the buffer id from the last descriptor Message-ID: <3fc9184844ddb9af89f6916a204df888d37565c1.1717527933.git.mst@redhat.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Wafer 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++) {