Re: vhost: Problem RESET_OWNER processing

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2015-08-08 02:04, Ouyang, Changchun wrote:
> 
> 
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jan Kiszka
>> Sent: Friday, August 7, 2015 10:04 PM
>> To: dev@dpdk.org; Xie, Huawei
>> Subject: [dpdk-dev] vhost: Problem RESET_OWNER processing
>>
>> Hi,
>>
>> I was wondering if I'm alone with this: the vhost-switch example crashes on
>> client disconnects if the client send a RESET_OWNER message. That's at least
>> the case for QEMU and vhost-user mode (I suppose vhost-cuse is legacy
> 
> What's your qemu version?

git head, which includes 2.4-rc2.

VHOST_USER_RESET_OWNER dates back to QEMU commit 294ce717e, and that is
after 2.3. Before that commit, QEMU was happily allowing its vhost
servers to corrupt guest memory on reboot or while a virtio device was
otherwise deactivated.

Jan

> 
>> now). And it really ruins the party when playing with this because every VM
>> shutdown or guest reboot triggers.
>>
>> I was looking deeper in the librte_vhost, and I found that reset_owner() is
>> doing cleanup_device and then init_device - but without letting the user
>> know. So vhost-switch crashed in its main loop over continuing to use the
>> device, namely calling rte_vhost_dequeue_burst (with
>> dev->virtqueue[]->avail == NULL).
>>
>> Do we simply need another hook in the vhost API, similar to the destruction
>> notification?
>>
>> Jan
>>
>> --
>> Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate
>> Competence Center Embedded Linux

-- 
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Corporate Competence Center Embedded Linux