On 04/17/2013 03:20 PM, Aurelien Jarno wrote: > On Tue, Apr 16, 2013 at 11:08:59AM +0800, Jason Wang wrote: >> On 04/15/2013 04:28 PM, Aurelien Jarno wrote: >>> On Mon, Apr 15, 2013 at 01:29:01PM +0800, Jason Wang wrote: >>>> On 04/13/2013 09:17 PM, Aurelien Jarno wrote: >>>>> On Fri, Jan 25, 2013 at 06:35:41PM +0800, Jason Wang wrote: >>>>>> This patch implements both userspace and vhost support for multiple queue >>>>>> virtio-net (VIRTIO_NET_F_MQ). This is done by introducing an array of >>>>>> VirtIONetQueue to VirtIONet. >>>>>> >>>>>> Signed-off-by: Jason Wang <jasow...@redhat.com> >>>>>> --- >>>>>> hw/virtio-net.c | 317 >>>>>> +++++++++++++++++++++++++++++++++++++++++++------------ >>>>>> hw/virtio-net.h | 28 +++++- >>>>>> 2 files changed, 275 insertions(+), 70 deletions(-) >>>>> This patch breaks virtio-net in Minix, even with multiqueue disable. I >>>>> don't know virtio enough to know if it is a Minix or a QEMU problem. >>>>> However I have been able to identify the part of the commit causing the >>>>> failure: >>>> Hi Aurelien: >>>> >>>> Thanks for the work. >>>>>> diff --git a/hw/virtio-net.c b/hw/virtio-net.c >>>>>> index ef522d5..cec91a7 100644 >>>>>> --- a/hw/virtio-net.c >>>>>> +++ b/hw/virtio-net.c >>>>> ... >>>>> >>>>>> +static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue, int >>>>>> ctrl) >>>>>> +{ >>>>>> + VirtIODevice *vdev = &n->vdev; >>>>>> + int i, max = multiqueue ? n->max_queues : 1; >>>>>> + >>>>>> + n->multiqueue = multiqueue; >>>>>> + >>>>>> + for (i = 2; i <= n->max_queues * 2 + 1; i++) { >>>>>> + virtio_del_queue(vdev, i); >>>>>> + } >>>>>> + >>>>> The for loop above is something which is new, even with multiqueue >>>>> disabled. Even with max_queues=1 it calls virtio_del_queue with i = 2 >>>>> and i = 3. Disabling this loop makes the code to work as before. >>>> Looks like a bug here, need to change n->max_queues * 2 + 1 to >>>> n->max_queues * 2. The reason we need to del queue 2 each time because >>>> vq 2 has different meaning is multiqueue and single queue. In single >>>> queue, vq 2 maybe ctrl vq, but in multiqueue mode it was rx1. >>>> >>>> Let's see whether this small change works. >>> Unfortunately it doesn't fix the issue. I don't know a lot about virtio, >>> but would it be possible to only delete the queue that have been >>> enabled? >> The issue is vq 2 has different meanings in two modes, so it must be >> deleted and reinitialized during feature negotiation. >>>>> On the Minix side it triggers the following assertion: >>>>> >>>>> | virtio.c:370: assert "q->vaddr != NULL" failed, function >>>>> "free_phys_queue" >>>>> >>>>> | virtio_net(73141): panic: assert failed >>>>> >>>>> This correspond to this function in lib/libvirtio/virtio.c: >>>>> >>>>> | static void >>>>> | free_phys_queue(struct virtio_queue *q) >>>>> | { >>>>> | assert(q != NULL); >>>>> | assert(q->vaddr != NULL); >>>>> | >>>>> | free_contig(q->vaddr, q->ring_size); >>>>> | q->vaddr = NULL; >>>>> | q->paddr = 0; >>>>> | q->num = 0; >>>>> | free_contig(q->data, sizeof(q->data[0])); >>>>> | q->data = NULL; >>>>> | } >>>>> >>>>> Do you have an idea if the problem is on the Minix side or on the QEMU >>>>> side? >>>>> >>>> Haven't figured out the relationship between virtqueue dynamic del/add >>>> and q->vaddr here. If the above changes does not work, I guess this >>> Unfortunately I don't really know the minix code either. I happen to >>> found the issue when testing other changes, and looked at the code to >>> try to understand the problem. >> Me too. >>>> problem happens only for ctrl vq (vq2)? And when does this happen? >>> I guess so given removing the call to virtio_del_queue() for vq2 fixes >>> or workarounds the issue. >> It will cause trouble for multiqueue guest who may think vq2 is rx queue. >>>> Rebooting? >>> It happens at the initial boot. >> Looks at the codes, looks like vq2 was initialized unconditionally at >> start, how about the following patch? >> >> diff --git a/hw/virtio-net.c b/hw/virtio-net.c >> index 4bb49eb..4886aa0 100644 >> --- a/hw/virtio-net.c >> +++ b/hw/virtio-net.c >> @@ -1300,7 +1300,6 @@ VirtIODevice *virtio_net_init(DeviceState *dev, >> NICConf *conf, >> virtio_net_handle_tx_bh); >> n->vqs[0].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[0]); >> } >> - n->ctrl_vq = virtio_add_queue(&n->vdev, 64, virtio_net_handle_ctrl); >> qemu_macaddr_default_if_unset(&conf->macaddr); >> memcpy(&n->mac[0], &conf->macaddr, sizeof(n->mac)); >> n->status = VIRTIO_NET_S_LINK_UP; >> > Unfortunately this patch doesn't work, I tried it with and without your > previous suggested change (max_queues * 2 + 1) => max_queues * 2. > > Aurelien >
Thanks for the test, I will try to get a minix to see what happens and keep you updated.