libvirt users - Oct 2020 - Re: scsi passthrough differs between guests

Greetings,

I have two machines running the same distro, both running qemu 5.1.0, one runs
libvirt 6.7.0, the other 6.8.0.
I've decided to test the viability of passing through my sata cdrom into a
vm, so I went to the libvirt docs, read a bit and added the following to a
debian10 uefi vm running on libvirt 6.8.0:
<controller type='scsi' index='0'
model='virtio-scsi'>
  <address type='pci' domain='0x0000' bus='0x07'
slot='0x00' function='0x0'/>
</controller>
<hostdev mode='subsystem' type='scsi'
managed='no'>
  <source>
    <adapter name='scsi_host11'/>
    <address bus='0' target='0' unit='0'/>
  </source>
  <readonly/>
  <address type='drive' controller='0' bus='0'
target='0' unit='0'/>
</hostdev>
I've booted the vm and saw the cdrom in the vm, eject worked and so did
mount.

I've decided to move it to another machine running libvirt 6.7.0, I've
verified the cdrom is visible on the new system, seE:
# lsscsi
[0:0:0:0]    cd/dvd  HL-DT-ST DVDRAM GH24NSD1  LW00  /dev/sr0

I've inserted the same xml into another vm running libreelec uefi but
changed the host from 11 to 0, it looks like this:
<controller type='scsi' index='0'
model='virtio-scsi'>
  <alias name='scsi0'/>
  <address type='pci' domain='0x0000' bus='0x02'
slot='0x01' function='0x0'/>
</controller>
<hostdev mode='subsystem' type='scsi'
managed='no'>
    <source>
    <adapter name='scsi_host0'/>
    <address bus='0' target='0' unit='0'/>
  </source>
  <readonly/>
  <alias name='hostdev0'/>
  <address type='drive' controller='0' bus='0'
target='0' unit='0'/>
</hostdev>

but when I boot the vm, I see no cdrom, lspci shows this:
03:00.0 SCSI storage controller: Red Hat, Inc. Virtio block device (rev 01)
07:01.0 SCSI storage controller: Red Hat, Inc. Virtio SCSI

as there is no lsscsi or /proc/scsi/scsi I cannot see other possible scsis.
I know for a fact that libreelec supports scsi/sata cdroms as it is a frequent
he for streamers.
I'm baffled about the two scsi controllers I see and why I cannot see the
device.
is there a known issue in 6.7.0 with scsi pass-trough?

Dagg.

On Wed, Oct 14, 2020 at 23:00:39 +0200, daggs wrote:
> Greetings,
[...]
> I'm baffled about the two scsi controllers I see and why I cannot see
the device.
> is there a known issue in 6.7.0 with scsi pass-trough?
I don't see anything wrong with you configs. There were some changes
related to SCSI hostdevs, between 6.7.0 an 6.8.0, but none of them
should actually impact that use case.

Said that, could you please post the actual qemu command lines that
libvirt formatted for the two VMs you mention above.

The command line can be found in /var/log/libvirt/qemu/$VMNAME.log .
Please make sure you post the latest/actual one. It'll help showing
whether anything changed between the two or there is a different
problem.

Greetings Peter,
> Sent: Thursday, October 15, 2020 at 9:52 AM
> From: "Peter Krempa" <pkrempa@redhat.com>
> To: "daggs" <daggs@gmx.com>
> Cc: "libvirt-usersredhat.com" <libvirt-users@redhat.com>
> Subject: Re: scsi passthrough differs between guests
>
> I don't see anything wrong with you configs. There were some changes
> related to SCSI hostdevs, between 6.7.0 an 6.8.0, but none of them
> should actually impact that use case.
>
> Said that, could you please post the actual qemu command lines that
> libvirt formatted for the two VMs you mention above.
>
> The command line can be found in /var/log/libvirt/qemu/$VMNAME.log .
> Please make sure you post the latest/actual one. It'll help showing
> whether anything changed between the two or there is a different
> problem.
>
here is the good cmd:
/usr/bin/qemu-system-x86_64 \
-name guest=debian10,debug-threads=on \
-S \
-object
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-debian10/master-key.aes
\
-blockdev
'{"driver":"file","filename":"/usr/share/edk2-ovmf/OVMF_CODE.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}'
\
-blockdev
'{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"raw","file":"libvirt-pflash0-storage"}'
\
-blockdev
'{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/debian9_VARS.fd","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}'
\
-blockdev
'{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"raw","file":"libvirt-pflash1-storage"}'
\
-machine
pc-q35-4.0,accel=kvm,usb=off,vmport=off,dump-guest-core=off,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format
\
-cpu host,migratable=on \
-m 6144 \
-overcommit mem-lock=off \
-smp 4,sockets=4,cores=1,threads=1 \
-uuid 84af935f-0afd-4021-a431-b6408a53efea \
-no-user-config \
-nodefaults \
-chardev socket,id=charmonitor,fd=26,server,nowait \
-mon chardev=charmonitor,id=monitor,mode=control \
-rtc base=utc,driftfix=slew \
-global kvm-pit.lost_tick_policy=delay \
-no-hpet \
-no-shutdown \
-global ICH9-LPC.disable_s3=1 \
-global ICH9-LPC.disable_s4=1 \
-boot strict=on \
-device
pcie-root-port,port=0x10,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,addr=0x2
\
-device pcie-root-port,port=0x11,chassis=2,id=pci.2,bus=pcie.0,addr=0x2.0x1 \
-device pcie-root-port,port=0x12,chassis=3,id=pci.3,bus=pcie.0,addr=0x2.0x2 \
-device pcie-root-port,port=0x13,chassis=4,id=pci.4,bus=pcie.0,addr=0x2.0x3 \
-device pcie-root-port,port=0x14,chassis=5,id=pci.5,bus=pcie.0,addr=0x2.0x4 \
-device pcie-root-port,port=0x15,chassis=6,id=pci.6,bus=pcie.0,addr=0x2.0x5 \
-device pcie-root-port,port=0x16,chassis=7,id=pci.7,bus=pcie.0,addr=0x2.0x6 \
-device qemu-xhci,p2=15,p3=15,id=usb,bus=pci.2,addr=0x0 \
-device virtio-scsi-pci,id=scsi0,bus=pci.7,addr=0x0 \
-device virtio-serial-pci,id=virtio-serial0,bus=pci.3,addr=0x0 \
-blockdev
'{"driver":"file","filename":"/home/virt_admin/Machines/kvm/debian10.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}'
\
-blockdev
'{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2","file":"libvirt-1-storage","backing":null}'
\
-device
virtio-blk-pci,bus=pci.4,addr=0x0,drive=libvirt-1-format,id=virtio-disk0,bootindex=2
\
-netdev tap,fd=28,id=hostnet0 \
-device
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:11:92:dd,bus=pci.1,addr=0x0
\
-chardev pty,id=charserial0 \
-device isa-serial,chardev=charserial0,id=serial0 \
-chardev socket,id=charchannel0,fd=29,server,nowait \
-device
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0
\
-vnc 127.0.0.1:0 \
-k en-us \
-device
qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pcie.0,addr=0x1
\
-device ich9-intel-hda,id=sound0,bus=pcie.0,addr=0x1b \
-device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 \
-drive file=/dev/sg5,if=none,format=raw,id=drive-hostdev0,readonly=on \
-device
scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-hostdev0,id=hostdev0
\
-device virtio-balloon-pci,id=balloon0,bus=pci.5,addr=0x0 \
-object rng-random,id=objrng0,filename=/dev/urandom \
-device virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.6,addr=0x0 \
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny
\
-msg timestamp=on

the bad one:
/usr/bin/qemu-system-x86_64 \
-name guest=streamer-vm-q35,debug-threads=on \
-S \
-object
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-12-streamer-vm-q35/master-key.aes
\
-blockdev
'{"driver":"file","filename":"/usr/share/qemu/edk2-x86_64-secure-code.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}'
\
-blockdev
'{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"raw","file":"libvirt-pflash0-storage"}'
\
-blockdev
'{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/streamer-vm-q35_VARS.fd","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}'
\
-blockdev
'{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"raw","file":"libvirt-pflash1-storage"}'
\
-machine
pc-q35-5.0,accel=kvm,usb=off,smm=on,dump-guest-core=off,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format
\
-cpu host,migratable=on \
-m 8192 \
-overcommit mem-lock=off \
-smp 1,maxcpus=2,sockets=1,dies=1,cores=1,threads=2 \
-uuid 4fb1463b-837c-40fc-a760-a69afc040a1a \
-display none \
-no-user-config \
-nodefaults \
-chardev socket,id=charmonitor,fd=25,server,nowait \
-mon chardev=charmonitor,id=monitor,mode=control \
-rtc base=utc,driftfix=slew \
-global kvm-pit.lost_tick_policy=delay \
-no-hpet \
-no-shutdown \
-global ICH9-LPC.disable_s3=1 \
-global ICH9-LPC.disable_s4=1 \
-boot strict=on \
-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
-device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 \
-device
pcie-root-port,port=0x8,chassis=3,id=pci.3,bus=pcie.0,multifunction=on,addr=0x1
\
-device pcie-root-port,port=0x9,chassis=4,id=pci.4,bus=pcie.0,addr=0x1.0x1 \
-device pcie-root-port,port=0xa,chassis=5,id=pci.5,bus=pcie.0,addr=0x1.0x2 \
-device pcie-root-port,port=0xb,chassis=6,id=pci.6,bus=pcie.0,addr=0x1.0x3 \
-device pcie-root-port,port=0xc,chassis=7,id=pci.7,bus=pcie.0,addr=0x1.0x4 \
-device qemu-xhci,id=usb,bus=pci.4,addr=0x0 \
-device virtio-scsi-pci,id=scsi0,bus=pci.2,addr=0x1 \
-blockdev
'{"driver":"file","filename":"/home/streamer/streamer.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}'
\
-blockdev
'{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2","file":"libvirt-1-storage","backing":null}'
\
-device
virtio-blk-pci,bus=pci.5,addr=0x0,drive=libvirt-1-format,id=virtio-disk0,bootindex=1
\
-netdev tap,fd=28,id=hostnet0 \
-device e1000e,netdev=hostnet0,id=net0,mac=52:54:00:5a:4c:8c,bus=pci.3,addr=0x0
\
-chardev pty,id=charserial0 \
-device isa-serial,chardev=charserial0,id=serial0 \
-blockdev
'{"driver":"host_device","filename":"/dev/sg0","node-name":"libvirt-hostdev0-backend","read-only":true}'
\
-device
scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=libvirt-hostdev0-backend,id=hostdev0
\
-device
vfio-pci,host=0000:00:02.0,id=hostdev1,bus=pci.7,addr=0x0,romfile=/home/streamer/gpu-8086:5902-uefi.rom
\
-device vfio-pci,host=0000:00:1f.3,id=hostdev2,bus=pci.2,addr=0x2 \
-device usb-host,id=hostdev3,bus=usb.0,port=1 \
-device usb-host,id=hostdev4,bus=usb.0,port=2 \
-device virtio-balloon-pci,id=balloon0,bus=pci.6,addr=0x0 \
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny
\
-msg timestamp=on

Dagg