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From: "Xie, Huawei" <huawei.xie@intel.com>
To: Tetsuya Mukawa <mukawa@igel.co.jp>, "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH RFC v2 08/12] lib/librte_vhost: vhost-user support
Date: Wed, 17 Dec 2014 01:06:18 +0000
Message-ID: <C37D651A908B024F974696C65296B57B0F326812@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <548FA172.5030604@igel.co.jp>

> > +{
> > +	struct virtio_net *dev = get_device(ctx);
> > +
> > +	/* We have to stop the queue (virtio) if it is running. */
> > +	if (dev->flags & VIRTIO_DEV_RUNNING)
> > +		notify_ops->destroy_device(dev);
> 
> I have an one concern about finalization of vrings.
> Can vhost-backend stop accessing RX/TX to the vring before replying to
> this message?
> 
> QEMU sends this message when virtio-net device is finalized by
> virtio-net driver on the guest.
> After finalization, memories used by the vring will be freed by
> virtio-net driver, because these memories are allocated by virtio-net
> driver.
> Because of this, I guess vhost-backend must stop accessing to vring
> before replying to this message.
> 
> I am not sure what is a good way to stop accessing.
> One idea is adding a condition checking when rte_vhost_dequeue_burst()
> and rte_vhost_enqueue_burst() is called.
> Anyway we probably need to wait for stopping access before replying.
> 
> Thanks,
> Tetsuya
> 
I think we have discussed the similar question.
It is actually the same issue whether the virtio APP in guest is crashed, or is finalized.
The virtio APP will only write to the STATUS register without waiting/syncing to vhost backend.
After that, not only the guest memory pointed by vring entry but also the vring itself isn't usable any more.
The memory for vring or pointed by vring entry might be used by other APPs.
This will crash guest(rather than the vhost, do you agree?).

If you mean this issue, I think we have no solution but one walk around: keep the huge page files of crashed app, and 
bind virtio to igb_uio and then delete the huge page files.

In our implementation, when vhost sends the message,  we will call the destroy_device provided by the vSwitch to ask the
vSwitch to stop processing the vring, but this willn't solve the issue I mention above, because the virtio APP in guest will n't 
wait us.

Could you explain a bit more? Is it the same issue?


-huawei

  reply	other threads:[~2014-12-17  1:06 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-10 21:37 [dpdk-dev] [PATCH RFC v2 00/12] " Huawei Xie
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 01/12] lib/librte_vhost: mov vhost-cuse implementation to vhost_cuse directory Huawei Xie
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 02/12] lib/librte_vhost: rename vhost-net-cdev.h as vhost-net.h Huawei Xie
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 03/12] lib/librte_vhost: move event_copy logic from virtio-net.c to vhost-net-cdev.c Huawei Xie
2015-01-07  9:10   ` Xie, Huawei
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 04/12] lib/librte_vhost: copy of host_memory_map from virtio-net.c to new file virtio-net-cdev.c Huawei Xie
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 05/12] lib/librte_vhost: host_memory_map refine Huawei Xie
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 06/12] lib/librte_vhost: cuse_set_memory_table Huawei Xie
2014-12-15  5:20   ` Tetsuya Mukawa
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 07/12] lib/librte_vhost: async event and callback Huawei Xie
2014-12-15  5:20   ` Tetsuya Mukawa
2014-12-17 17:51     ` Xie, Huawei
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 08/12] lib/librte_vhost: vhost-user support Huawei Xie
2014-12-11  5:36   ` Linhaifeng
2015-01-05 10:21     ` Xie, Huawei
2015-01-23  3:40     ` Xie, Huawei
2015-01-23  3:53       ` Linhaifeng
2014-12-11  6:04   ` Linhaifeng
2014-12-11 17:13     ` Xie, Huawei
2014-12-12  2:25       ` Linhaifeng
2014-12-11 20:16     ` Xie, Huawei
2015-01-23  3:36     ` Xie, Huawei
2015-01-23  8:36       ` Linhaifeng
2014-12-16  3:05   ` Tetsuya Mukawa
2014-12-17  1:06     ` Xie, Huawei [this message]
2014-12-17  3:31       ` Tetsuya Mukawa
2014-12-17  4:22         ` Tetsuya Mukawa
2014-12-17 17:31           ` Xie, Huawei
2014-12-19  3:36             ` Tetsuya Mukawa
2014-12-24  7:21   ` Tetsuya Mukawa
2015-01-04  9:53     ` Xie, Huawei
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 09/12] lib/librte_vhost: minor fix Huawei Xie
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 10/12] lib/librte_vhost: vhost-user memory region map Huawei Xie
2014-12-16  2:38   ` Tetsuya Mukawa
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 11/12] lib/librte_vhost: kick/callfd fix Huawei Xie
2014-12-10 21:37 ` [dpdk-dev] [PATCH RFC v2 12/12] lib/librte_vhost: cleanup when vhost user socket connection is closed Huawei Xie
2014-12-10 22:04 ` [dpdk-dev] [PATCH RFC v2 00/12] lib/librte_vhost: vhost-user support Xie, Huawei
2014-12-11  2:21   ` Tetsuya Mukawa
2014-12-15  5:26 ` Tetsuya Mukawa
2014-12-17 17:43   ` Xie, Huawei
2015-01-07 12:43     ` Qiu, Michael
2015-01-23  8:16 ` Linhaifeng
2015-01-26  7:24   ` Xie, Huawei

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