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From: Marc Olson <marcolso@amazon.com>
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Date: Sun, 11 Nov 2018 23:13:46 -0800
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Subject: Re: [Qemu-devel] How to emulate block I/O timeout on qemu side?
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To: Dongli Zhang <dongli.zhang@oracle.com>, John Snow <jsnow@redhat.com>
Cc: qemu-devel@nongnu.org, Qemu-block <qemu-block@nongnu.org>

On 11/3/18 10:24 AM, Dongli Zhang wrote:
> Hi all,
>
> I tried with the patch at:
>
> https://lists.gnu.org/archive/html/qemu-devel/2018-09/msg00394.html
>
> The patch is applied to qemu-3.0.0.
>
>
> Below configuration is used to test the feature for guest VM nvme.
>
> # qemu-system-x86_64 \
> -smp 4 -m 2000M -enable-kvm -vnc :0 -monitor stdio \
> -net nic -net user,hostfwd=tcp::5022-:22 \
> -drive file=virtio-disk.img,format=raw,if=none,id=disk0 \
> -device virtio-blk-pci,drive=disk0,id=disk0-dev,num-queues=2,iothread=io1 \
> -object iothread,id=io1 \
> -device nvme,drive=nvme1,serial=deadbeaf1 \
> -drive file=blkdebug:blkdebug.config:nvme.img,if=none,id=nvme1
>
> # cat blkdebug.config
> [delay]
> event = "write_aio"
> latency = "9999999999"
> sector = "40960"
>
>
> The 'write' latency of sector=40960 is set to a very large value. When the I/O
> is stalled in guest due to that sector=40960 is accessed, I do see below
> messages in guest log:
>
> [   80.807755] nvme nvme0: I/O 11 QID 2 timeout, aborting
> [   80.808095] nvme nvme0: Abort status: 0x4001
>
>
> However, then nothing happens further. nvme I/O hangs in guest. I am not able to
> kill the qemu process with Ctrl+C. Both vnc and qemu user net do not work. I
> need to kill qemu with "kill -9"
>
>
> The same result for virtio-scsi and qemu is stuck as well.
While I didn't try virtio-scsi, I wasn't able to reproduce this behavior 
using nvme on Ubuntu 18.04 (4.15). What image and kernel version are you 
trying against?

/marc