[Bug 1892581] [NEW] QEMU 5.1 no longer says anything about inaccessible devices

[Diego Viola]

Public bug reported:

Previously, with QEMU 5.0.0 running a VM with the following command:

$ qemu-system-x86_64 -enable-kvm -hda arch-zoom.qcow2 -m 4G -device usb-
ehci,id=ehci -device usb-
host,bus=ehci.0,vendorid=0x04f2,productid=0xb449 -device intel-hda
-device hda-duplex -vga virtio

Would display something like the following:

libusb: error [_get_usbfs_fd] libusb couldn't open USB device 
/dev/bus/usb/002/004: Permission denied
libusb: error [_get_usbfs_fd] libusb requires write access to USB device nodes.
libusb: error [_get_usbfs_fd] libusb couldn't open USB device 
/dev/bus/usb/002/004: Permission denied
libusb: error [_get_usbfs_fd] libusb requires write access to USB device nodes.

With insufficient permissions.

QEMU 5.1.0 no longer displays anything.

I did a git bisect and this is the result:

[diego@thinkpad qemu]$ git bisect bad
9f815e83e983d247a3cd67579d2d9c1765adc644 is the first bad commit
commit 9f815e83e983d247a3cd67579d2d9c1765adc644
Author: Gerd Hoffmann <kraxel@redhat.com>
Date:   Fri Jun 5 14:59:52 2020 +0200

    usb: add hostdevice property to usb-host

    The new property allows to specify usb host device name.  Uses standard
    qemu_open(), so both file system path (/dev/bus/usb/$bus/$dev on linux)
    and file descriptor passing can be used.

    Requires libusb 1.0.23 or newer.  The hostdevice property is only
    present in case qemu is compiled against a new enough library version,
    so the presence of the property can be used for feature detection.

    Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
    Message-Id: <20200605125952.13113-1-kraxel@redhat.com>

 hw/usb/host-libusb.c | 75 ++++++++++++++++++++++++++++++++++++++++++----------
 hw/usb/trace-events  |  1 +
 2 files changed, 62 insertions(+), 14 deletions(-)
[diego@thinkpad qemu]$

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1892581

Title:
  QEMU 5.1 no longer says anything about inaccessible devices

Status in QEMU:
  New

Bug description:
  Previously, with QEMU 5.0.0 running a VM with the following command:

  $ qemu-system-x86_64 -enable-kvm -hda arch-zoom.qcow2 -m 4G -device
  usb-ehci,id=ehci -device usb-
  host,bus=ehci.0,vendorid=0x04f2,productid=0xb449 -device intel-hda
  -device hda-duplex -vga virtio

  Would display something like the following:

  libusb: error [_get_usbfs_fd] libusb couldn't open USB device 
/dev/bus/usb/002/004: Permission denied
  libusb: error [_get_usbfs_fd] libusb requires write access to USB device 
nodes.
  libusb: error [_get_usbfs_fd] libusb couldn't open USB device 
/dev/bus/usb/002/004: Permission denied
  libusb: error [_get_usbfs_fd] libusb requires write access to USB device 
nodes.

  With insufficient permissions.

  QEMU 5.1.0 no longer displays anything.

  I did a git bisect and this is the result:

  [diego@thinkpad qemu]$ git bisect bad
  9f815e83e983d247a3cd67579d2d9c1765adc644 is the first bad commit
  commit 9f815e83e983d247a3cd67579d2d9c1765adc644
  Author: Gerd Hoffmann <kraxel@redhat.com>
  Date:   Fri Jun 5 14:59:52 2020 +0200

      usb: add hostdevice property to usb-host

      The new property allows to specify usb host device name.  Uses standard
      qemu_open(), so both file system path (/dev/bus/usb/$bus/$dev on linux)
      and file descriptor passing can be used.

      Requires libusb 1.0.23 or newer.  The hostdevice property is only
      present in case qemu is compiled against a new enough library version,
      so the presence of the property can be used for feature detection.

      Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
      Message-Id: <20200605125952.13113-1-kraxel@redhat.com>

   hw/usb/host-libusb.c | 75 
++++++++++++++++++++++++++++++++++++++++++----------
   hw/usb/trace-events  |  1 +
   2 files changed, 62 insertions(+), 14 deletions(-)
  [diego@thinkpad qemu]$

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