> From: Peng Hao <[email protected]> > > Since commit 69b9461512246 ("virtio_pci_modern: allow configuring > extended features") the modern virtio-pci driver unconditionally > accesses the whole 128 bits features space, i.e. it drives > device_feature_select / guest_feature_select with the values 0..3. > > Devices predating the extended features space only implement the > legacy 64 bits one, and what they report for the selectors above it is > not a valid features space. Negotiating it makes the driver and the > device end up with different features sets: on a smart NIC exposing a > virtio_net device the link comes up but carries no traffic, while the > same device works with a kernel that only accesses the low 64 bits. > > Reading the features space has no side effect, so keep reading all of > [ ... ] > Conforming devices are unaffected: their extended words are neither > all-ones nor an alias of the low ones, so the detection does not > trigger. > > Signed-off-by: Peng Hao <[email protected]>
Sashiko has reviewed this patch and found no issues. It looks great! -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
