[Bug 1863333] Re: Assigning NVMe disk to a domain causes VFIO_MAP_DMA errors

[Thomas Huth]

This is an automated cleanup. This bug report has been moved
to QEMU's new bug tracker on gitlab.com and thus gets marked
as 'expired' now. Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/65


** Changed in: qemu
       Status: New => Expired

** Changed in: qemu
     Assignee: Philippe Mathieu-Daudé (philmd) => (unassigned)

** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #65
   https://gitlab.com/qemu-project/qemu/-/issues/65

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https://bugs.launchpad.net/bugs/1863333

Title:
  Assigning NVMe disk to a domain causes VFIO_MAP_DMA errors

Status in QEMU:
  Expired

Bug description:
  I'm seeing some errors when assigning my NVMe disk to qemu. This is
  the full command line:

  
  /home/zippy/work/qemu/qemu.git/x86_64-softmmu/qemu-system-x86_64 \
  -name guest=fedora,debug-threads=on \
  -S \
  -object 
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-2-fedora/master-key.aes
 \
  -machine pc-i440fx-4.1,accel=kvm,usb=off,dump-guest-core=off \
  -cpu host \
  -m size=4194304k,slots=16,maxmem=1099511627776k \
  -overcommit mem-lock=off \
  -smp 4,sockets=1,dies=1,cores=2,threads=2 \
  -object iothread,id=iothread1 \
  -object iothread,id=iothread2 \
  -object iothread,id=iothread3 \
  -object iothread,id=iothread4 \
  -mem-prealloc \
  -mem-path /hugepages2M/libvirt/qemu/2-fedora \
  -numa node,nodeid=0,cpus=0,mem=4096 \
  -uuid 63840878-0deb-4095-97e6-fc444d9bc9fa \
  -no-user-config \
  -nodefaults \
  -chardev socket,id=charmonitor,fd=31,server,nowait \
  -mon chardev=charmonitor,id=monitor,mode=control \
  -rtc base=utc \
  -no-shutdown \
  -global PIIX4_PM.disable_s3=0 \
  -global PIIX4_PM.disable_s4=0 \
  -boot menu=on,strict=on \
  -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \
  -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x4 \
  -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 \
  -blockdev 
'{"driver":"file","filename":"/var/lib/libvirt/images/fedora.qcow2","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}'
 \
  -blockdev 
'{"node-name":"libvirt-2-format","read-only":false,"discard":"unmap","driver":"qcow2","file":"libvirt-2-storage","backing":null}'
 \
  -device 
scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,device_id=drive-scsi0-0-0-0,drive=libvirt-2-format,id=scsi0-0-0-0,bootindex=1
 \
  -blockdev 
'{"driver":"nvme","device":"0000:02:00.0","namespace":1,"node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}'
 \
  -blockdev 
'{"node-name":"libvirt-1-format","read-only":false,"driver":"raw","file":"libvirt-1-storage"}'
 \
  -device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=libvirt-1-format,id=virtio-disk0
 \
  -netdev tap,fd=33,id=hostnet0,vhost=on,vhostfd=34 \
  -device 
virtio-net-pci,host_mtu=9000,netdev=hostnet0,id=net0,mac=52:54:00:a4:6f:91,bus=pci.0,addr=0x3
 \
  -chardev pty,id=charserial0 \
  -device isa-serial,chardev=charserial0,id=serial0 \
  -chardev socket,id=charchannel0,fd=35,server,nowait \
  -device 
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0
 \
  -spice port=5900,addr=0.0.0.0,disable-ticketing,seamless-migration=on \
  -device virtio-vga,id=video0,virgl=on,max_outputs=1,bus=pci.0,addr=0x2 \
  -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 \
  -sandbox 
on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
  -msg timestamp=on

  And these are the errors I see:

  2020-02-14T09:06:18.183167Z qemu-system-x86_64: VFIO_MAP_DMA failed: Invalid 
argument
  2020-02-14T09:10:49.753767Z qemu-system-x86_64: VFIO_MAP_DMA failed: Cannot 
allocate memory
  2020-02-14T09:11:04.530344Z qemu-system-x86_64: VFIO_MAP_DMA failed: No space 
left on device
  2020-02-14T09:11:04.531087Z qemu-system-x86_64: VFIO_MAP_DMA failed: No space 
left on device
  2020-02-14T09:11:04.531230Z qemu-system-x86_64: VFIO_MAP_DMA failed: No space 
left on device

  
  I'm doing nothing with the disk inside the guest, but:

    # dd if=/dev/vda of=/dev/null status=progress

  (the disk appears as /dev/vda in the guest). Surprisingly, I do not
  see these errors when I use the traditional PCI assignment (-device
  vfio-pci). My versions of kernel and qemu:

  moe ~ # uname -r
  5.4.15-gentoo
  moe ~ # /home/zippy/work/qemu/qemu.git/x86_64-softmmu/qemu-system-x86_64 
--version
  QEMU emulator version 4.2.50 (v4.2.0-1439-g5d6542bea7-dirty)
  Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers

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