diff options
Diffstat (limited to 'gitlab/issues_text/target_missing/host_missing/accel_missing/1342')
| -rw-r--r-- | gitlab/issues_text/target_missing/host_missing/accel_missing/1342 | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/gitlab/issues_text/target_missing/host_missing/accel_missing/1342 b/gitlab/issues_text/target_missing/host_missing/accel_missing/1342 new file mode 100644 index 000000000..47664e458 --- /dev/null +++ b/gitlab/issues_text/target_missing/host_missing/accel_missing/1342 @@ -0,0 +1,24 @@ +Default machine setting of force-legacy=true causes problems for any modern VirtIO device using MMIO +Description of problem: +The default causes problems if you enable any non-legacy VirtIO device which has the VIRTIO_F_VERSION_1 feature bit will not properly read all feature bits. This is because reading VIRTIO_MMIO_VERSION returns VIRT_VERSION_LEGACY which in turn results in the driver not reading all feature bits, e.g. the qtest access: + +``` +static uint64_t qvirtio_mmio_get_features(QVirtioDevice *d) +{ + QVirtioMMIODevice *dev = container_of(d, QVirtioMMIODevice, vdev); + uint64_t lo; + uint64_t hi = 0; + + qtest_writel(dev->qts, dev->addr + QVIRTIO_MMIO_HOST_FEATURES_SEL, 0); + lo = qtest_readl(dev->qts, dev->addr + QVIRTIO_MMIO_HOST_FEATURES); + + if (dev->version >= 2) { + qtest_writel(dev->qts, dev->addr + QVIRTIO_MMIO_HOST_FEATURES_SEL, 1); + hi = qtest_readl(dev->qts, dev->addr + QVIRTIO_MMIO_HOST_FEATURES); + } + + return (hi << 32) | lo; +} +``` +Additional information: + |