On 2017/11/16 20:04, Jason Wang wrote:
> > > On 2017年11月16日 17:32, Longpeng (Mike) wrote: >> Hi Jason, >> >> On 2017/11/16 17:13, Jason Wang wrote: >> >>> >>> On 2017年11月16日 17:01, Gonglei (Arei) wrote: >>>> No, Windows guest + vhost-user/DPDK. >>>> >>>> BTW pls see virtio spec in : >>>> >>>> "If VIRTIO_NET_F_MQ is negotiated, each of receiveq1. . .receiveqN that >>>> will >>>> be used SHOULD be populated >>>> with receive buffers." >>>> >>>> It is not mandatory that all queues must be initialized. >>> I think not, since it said we should fill receive buffers for each queue >>> which >>> means we should initialize all queues. May Michael can clarify on this. >>> >> >> I think this doesn't matter, but QEMU should consider this scenario... >> >> For example, if one queues isn't initialized (Windows guest), the >> vring.avail=0, >> so vq->desc_phys=0, then vq->desc='a avail HVA'(which is the start addr of >> pc.ram). >> >> vq->desc_size = s = l = virtio_queue_get_desc_size(vdev, idx); >> vq->desc_phys = a = virtio_queue_get_desc_addr(vdev, idx); >> vq->desc = vhost_memory_map(dev, a, &l, 0); >> if (!vq->desc || l != s) { >> r = -ENOMEM; >> goto fail_alloc_desc; >> } >> ..... >> r = vhost_virtqueue_set_addr(dev, vq, vhost_vq_index, dev->log_enabled); >> if (r < 0) { >> r = -errno; >> goto fail_alloc; >> } >> >> Then the HVA is send to the vhost-user. >> >> I think this is wrong, because the '0' here means guest driver doesn't init >> this >> queues, it should not be used to calculate the HVA for this vq. > > Yes, workaround is not hard if windows driver won't use the left 3 queues any > more. But we should have a complete solution. The main problem is when vhost > need to be started. For legacy device, there's no easy way to detect whether > or > not a specific virtqueue is ready to be used. For modern device, we can > probably > do this through queue_enable (but this is not implemented in current code). > Can we initialize the vring.desc/vring.avail/vring.used to -1, then we can detect whether or not a specific vq is ready to be used by check the addr of its tables is -1 or not ? Initialize to 0 is not suitable, because we don't know whether the guest set GPA 0 or the guest not initialize this vq. > Thanks > >> >>> Thanks >>> >>>> Thanks, >>>> -Gonglei >>>> >>> >>> >>> >>> . >>> >> > > > . > -- Regards, Longpeng(Mike)