pc,virtio: features, tests, fixes, cleanups

[PULL 05/55] hw/virtio: log potentially buggy guest drivers

Michael S. Tsirkin posted 55 patches 3 years, 2 months ago

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Maintainers: "Dr. David Alan Gilbert" <dgilbert@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <ani@anisinha.ca>, Peter Maydell <peter.maydell@linaro.org>, Shannon Zhao <shannon.zhaosl@gmail.com>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, Raphael Norwitz <raphael.norwitz@nutanix.com>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Peter Xu <peterx@redhat.com>, Jason Wang <jasowang@redhat.com>, Ben Widawsky <ben.widawsky@intel.com>, Jonathan Cameron <jonathan.cameron@huawei.com>, Fam Zheng <fam@euphon.net>, "Alex Bennée" <alex.bennee@linaro.org>, Viresh Kumar <viresh.kumar@linaro.org>, Mathieu Poirier <mathieu.poirier@linaro.org>, Markus Armbruster <armbru@redhat.com>, Michael Roth <michael.roth@amd.com>, Eric Blake <eblake@redhat.com>, Thomas Huth <thuth@redhat.com>, Laurent Vivier <lvivier@redhat.com>

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[PULL 05/55] hw/virtio: log potentially buggy guest drivers

Posted by Michael S. Tsirkin 3 years, 2 months ago

From: Alex Bennée <alex.bennee@linaro.org>

If the guest driver attempts to use the UNUSED(30) bit it is
potentially buggy as 6.3 Legacy Interface: Reserved Feature Bits
states it "SHOULD NOT be negotiated". For now just log this guest
error.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220802095010.3330793-9-alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/virtio.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 5d607aeaa0..97a6307c0f 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2980,6 +2980,13 @@ int virtio_set_features(VirtIODevice *vdev, uint64_t val)
     if (vdev->status & VIRTIO_CONFIG_S_FEATURES_OK) {
         return -EINVAL;
     }
+
+    if (val & (1ull << VIRTIO_F_BAD_FEATURE)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: guest driver for %s has enabled UNUSED(30) feature bit!\n",
+                      __func__, vdev->name);
+    }
+
     ret = virtio_set_features_nocheck(vdev, val);
     if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
         /* VIRTIO_RING_F_EVENT_IDX changes the size of the caches.  */
-- 
MST