Re: [Qemu-devel] vhost-user: VHOST_SET_MEM_TABLE, VHOST_SET_VRING_CALL need a reply?

[Linhaifeng <haifeng.lin@huawei.com>]

On 2014/9/17 17:56, Michael S. Tsirkin wrote:
> On Wed, Sep 17, 2014 at 05:39:04PM +0800, Linhaifeng wrote:
>> I think maybe is not need for the backend to wait for response.
>>
>> There is another way.vhost-user send "VHOST_GET_MEM_TABLE" to qemu then qemu send VHOST_SET_MEM_TABLE to update the regions of vhost-user.same as other command.
>> If qemu could response the request of the vhost-user.the vhost-user could update date at anytime.
> 
> The updates are initiated by QEMU, as a result of IOMMU,
> memory hotplug or some other configuration change.

How to deal with the vhost-user restart?
when vhost-user restart it will lost the infomation which QEMU send.

In the kernel mode vhost will restart with QEMU but in the user mode vhost will not.

> 
>> I think it's very useful for Commercialization.
>>
>> On 2014/9/17 16:38, Michael S. Tsirkin wrote:
>>> Reply-To: 
>>>
>>> Thinking about the vhost-user protocol, VHOST_SET_MEM_TABLE
>>> is used to update the memory mappings.
>>>
>>> So shouldn't we want for response?
>>> Otherwise e.g. guest can start using the memory
>>> that vhost-user can't access.
>>>
>>> Similarly, with an IOMMU vhost-user might access memory it shouldn't.
>>>
>>> VHOST_SET_VRING_CALL is used for MSI-X masking.
>>> Again, after vector is masted by switching the call fd,
>>> backend shouldn't assert the old one.
>>>
>>> Thoughts?
>>>
>>>
> 
> .
>