[PATCH v3 0/3] vdpa: Return -EIO if device ack is VIRTIO_NET_ERR

[Hawkins Jiawei <yin31149@gmail.com>]

According to VirtIO standard, "The class, command and
command-specific-data are set by the driver,
and the device sets the ack byte.
There is little it can do except issue a diagnostic
if ack is not VIRTIO_NET_OK."

Therefore, QEMU should stop sending the queued SVQ commands and
cancel the device startup if the device's ack is not VIRTIO_NET_OK.

Yet the problem is that, vhost_vdpa_net_load_x() returns 1 based on
`*s->status != VIRTIO_NET_OK` when the device's ack is VIRTIO_NET_ERR.
As a result, net->nc->info->load() also returns 1, this makes
vhost_net_start_one() incorrectly assume the device state is
successfully loaded by vhost_vdpa_net_load() and return 0, instead of
goto `fail` label to cancel the device startup, as vhost_net_start_one()
only cancels the device startup when net->nc->info->load() returns a
negative value.

This patchset fixes this problem by returning -EIO when the device's
ack is not VIRTIO_NET_OK.

Changelog
=========
v3:
 - split the fixes suggested by Eugenio
 - return -EIO suggested by Michael

v2: https://lore.kernel.org/all/69010e9ebb5e3729aef595ed92840f43e48e53e5.1687875592.git.yin31149@gmail.com/
 - fix the same bug in vhost_vdpa_net_load_offloads()

v1: https://lore.kernel.org/all/cover.1686746406.git.yin31149@gmail.com/

Hawkins Jiawei (3):
  vdpa: Return -EIO if device ack is VIRTIO_NET_ERR in _load_mac()
  vdpa: Return -EIO if device ack is VIRTIO_NET_ERR in _load_mq()
  vdpa: Return -EIO if device ack is VIRTIO_NET_ERR in _load_offloads()

 net/vhost-vdpa.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

-- 
2.25.1