hw/virtio: enable common virtio feature for mmio device
Both 'indirect_desc' and 'event_idx' are bus independent features,
and they should be enabled for mmio devices too.
On arm64 quad core VM(qemu-kvm), the patch can increase block I/O
performance a lot with latest linux tree:
- without the patch: 14K IOPS
- with the patch: 34K IOPS
fio script:
[global]
direct=1
bsrange=4k-4k
timeout=10
numjobs=4
ioengine=libaio
iodepth=64
filename=/dev/vdc
group_reporting=1
[f1]
rw=randread
Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>