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

[Felipe Franciosi]

> 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
vhost-scsi does, but I'd prefer to tackle that separately because I
can't trivially test it. If it breaks something there, we can revert
it without affecting a valid fix for vhost-user-scsi.

I can send that patch immediately after this is queued (or resend a v2
including both patches separately if maintainers prefer that).

F.

> 
> Thanks,
> Yongji
> 
>> Signed-off-by: Felipe Franciosi <address@hidden>
>> ---
>> hw/scsi/vhost-user-scsi.c | 9 +++++----
>> 1 file changed, 5 insertions(+), 4 deletions(-)
>> 
>> diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
>> index 6a6c15dd32..13278ed151 100644
>> --- a/hw/scsi/vhost-user-scsi.c
>> +++ b/hw/scsi/vhost-user-scsi.c
>> @@ -62,8 +62,9 @@ static void vhost_user_scsi_set_status(VirtIODevice *vdev, 
>> uint8_t status)
>>     }
>> }
>> 
>> -static void vhost_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>> +static void vhost_handle_output(VirtIODevice *vdev, VirtQueue *vq)
>> {
>> +    event_notifier_set(virtio_queue_get_host_notifier(vq));
>> }
>> 
>> static void vhost_user_scsi_realize(DeviceState *dev, Error **errp)
>> @@ -80,9 +81,9 @@ static void vhost_user_scsi_realize(DeviceState *dev, 
>> Error **errp)
>>         return;
>>     }
>> 
>> -    virtio_scsi_common_realize(dev, vhost_dummy_handle_output,
>> -                               vhost_dummy_handle_output,
>> -                               vhost_dummy_handle_output, &err);
>> +    virtio_scsi_common_realize(dev, vhost_handle_output,
>> +                               vhost_handle_output,
>> +                               vhost_handle_output, &err);
>>     if (err != NULL) {
>>         error_propagate(errp, err);
>>         return;
>> --
>> 2.20.1
>>