Disable scsi disk requests in QEMU when using virtio-blk device

[Arnabjyoti Kalita]

Hello all,

Is it possible to disable scsi disk requests being generated by the
guest when using a virtio-blk device?

I am starting the guest in KVM mode using the below command line-

sudo ./qemu-system-x86_64 -m 1024 --machine pc-i440fx-2.5 -cpu
qemu64,-kvmclock,-kvm_pv_eoi
-enable-kvm -netdev tap,id=tap1,ifname=tap0,script=no,downscript=no
-device virtio-net-pci,netdev=tap1,mac=00:00:00:00:00:00 -object
filter-replay,id=replay,netdev=tap1
-drive 
file=~/os_images_for_qemu/ubuntu-16.04-desktop-amd64.qcow2,format=qcow2,if=none,id=img-direct
-device virtio-blk-pci,drive=img-direct

I keep seeing some interrupts being generated as a result of scsi
requests, which I really want to disable.

GDB backtrace output -

bt
#0  blk_update_request (req=0xffff88003548e450, error=0, nr_bytes=8)
at /build/linux-Ay7j_C/linux-4.4.0/block/blk-core.c:2568
#1  0xffffffff815ad873 in scsi_end_request (req=0xffff88003548e450,
error=<optimized out>, bytes=<optimized out>, bidi_bytes=<optimized
out>) at /build/linux-Ay7j_C/linux-4.4.0/drivers/scsi/scsi_lib.c:695
#2  0xffffffff815b09c4 in scsi_io_completion (cmd=0xffff88003548e450,
good_bytes=<optimized out>) at
/build/linux-Ay7j_C/linux-4.4.0/drivers/scsi/scsi_lib.c:915
#3  0xffffffff815a7b4f in scsi_finish_command (cmd=0xffff880002237a80)
at /build/linux-Ay7j_C/linux-4.4.0/drivers/scsi/scsi.c:607
#4  0xffffffff815b0244 in scsi_softirq_done (rq=<optimized out>) at
/build/linux-Ay7j_C/linux-4.4.0/drivers/scsi/scsi_lib.c:1640
#5  0xffffffff813c1d37 in blk_done_softirq (h=<optimized out>) at
/build/linux-Ay7j_C/linux-4.4.0/block/blk-softirq.c:35
#6  0xffffffff810859a1 in __do_softirq () at
/build/linux-Ay7j_C/linux-4.4.0/kernel/softirq.c:273
#7  0xffffffff81085ca3 in invoke_softirq () at
/build/linux-Ay7j_C/linux-4.4.0/kernel/softirq.c:350

Is there a command line switch or parameter that will disable
generation of scsi requests and its associated interrupts? The scsi
module is built into the guest kernel (kernel version 4.4.0).

Note: I am using QEMU version 5.0.1 and my host and target
architecture is x86_64.

Thank you very much.

Best Regards,
Arnab