Re: [PATCH] vhost-user-scsi: implement handle_output

[Felipe Franciosi]

> On Oct 21, 2019, at 5:01 AM, Yongji Xie <address@hidden> wrote:
> 
> On Fri, 18 Oct 2019 at 19:14, Felipe Franciosi <address@hidden> wrote:
>> 
>> 
>> 
>>> On Oct 18, 2019, at 3:59 AM, Yongji Xie <address@hidden> wrote:
>>> 
>>> On Fri, 18 Oct 2019 at 01:17, Felipe Franciosi <address@hidden> wrote:
>>>> 
>>>> Originally, vhost-user-scsi did not implement a handle_output callback
>>>> as that didn't seem necessary. Turns out it is.
>>>> 
>>>> Depending on which other devices are presented to a VM, SeaBIOS may
>>>> decide to map vhost-user-scsi devices on the 64-bit range of the address
>>>> space. As a result, SeaBIOS will kick VQs via the config space. Those
>>>> land on Qemu (not the vhost backend) and are missed, causing the VM not
>>>> to boot. This fixes the issue by getting Qemu to post the notification.
>>>> 
>>> Should we fix this in vhost-user-blk too?
>> 
>> I'm not sure vhost-user-blk suffers from the same problem. Certainly
> 
> Actually I found vhost-user-blk has the same problem in a mutilple
> GPUs passthough environment.

Let's Cc Changpeng for comments. I'm not familiar with that code.

In any case, I still think we should merge this and fix other
implementations separately. That allows us to revert patches
individually if anything else breaks.

F.

> 
> Thanks,
> Yongji