[v3] virtio: features,fixes

[PULL v3 11/85] hw/virtio: Fix obtain the buffer id from the last descriptor

Michael S. Tsirkin posted 85 patches 2 months, 2 weeks ago

Diff against v1 v1 v2 v2 v3
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Maintainers: David Hildenbrand <david@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Raphael Norwitz <raphael@enfabrica.net>, "Michael S. Tsirkin" <mst@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Shannon Zhao <shannon.zhaosl@gmail.com>, Ani Sinha <anisinha@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, Jonathan Cameron <jonathan.cameron@huawei.com>, Fan Ni <fan.ni@samsung.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Sergio Lopez <slp@redhat.com>, Akihiko Odaki <akihiko.odaki@daynix.com>, Sriram Yagnaraman <sriram.yagnaraman@ericsson.com>, Jason Wang <jasowang@redhat.com>, Keith Busch <kbusch@kernel.org>, Klaus Jensen <its@irrelevant.dk>, Jesper Devantier <foss@defmacro.it>, Nicholas Piggin <npiggin@gmail.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Thomas Huth <thuth@redhat.com>, Fam Zheng <fam@euphon.net>, "Alex Bennée" <alex.bennee@linaro.org>, Stefan Hajnoczi <stefanha@redhat.com>, Eric Auger <eric.auger@redhat.com>, Stefano Stabellini <sstabellini@kernel.org>, Anthony PERARD <anthony@xenproject.org>, Paul Durrant <paul@xen.org>, Cornelia Huck <cohuck@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>, David Woodhouse <dwmw2@infradead.org>, Laurent Vivier <lvivier@redhat.com>, Coiby Xu <Coiby.Xu@gmail.com>

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[PULL v3 11/85] hw/virtio: Fix obtain the buffer id from the last descriptor

Posted by Michael S. Tsirkin 2 months, 2 weeks ago

From: Wafer <wafer@jaguarmicro.com>

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>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20240510072753.26158-2-wafer@jaguarmicro.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 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++) {
-- 
MST