USB block devices disappear from AppVM after resuming from sleep (TP X250). Will debug

[Pablo Di Noto]

Hello,

I have a recurring issue:
- Start system
- Start a debian-8 AppVM
- Insert a USB drive to a USB port (this system has a sys-usb VM with all controllers in it)
- I connect that USB block device to the AppVM
- New device /dev/xvdi appears, I mount it without issue (it is LUKS volume)
- Use the filesystem on the USB without any issue
...until
- System goes to sleep (no matter which way, by idle timeout or explicit request)
- After resume, the AppVM has lost the device, but dom0 has it connected.
- Any attempt to have qubes disconnect the device results in errors in libxl

I know this is not a complete report, I just want to know what kind of debug I can enable on qvm-block or the Qubes VM Manager itself, and if there is any kernel or xen options that will provide useful info.

I am using Qubes 3.2rc1, but this was happening on R3.1 exactly the same way.

Does not happen on the desktop machine I use.

Thanks in advance,
///Pablo

[Marek Marczykowski-Górecki]

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On Mon, Jul 11, 2016 at 05:11:44PM -0700, Pablo Di Noto wrote:
> Hello,
>
> I have a recurring issue:
> - Start system
> - Start a debian-8 AppVM
> - Insert a USB drive to a USB port (this system has a sys-usb VM with all controllers in it)
> - I connect that USB block device to the AppVM
> - New device /dev/xvdi appears, I mount it without issue (it is LUKS volume)
> - Use the filesystem on the USB without any issue
> ...until
> - System goes to sleep (no matter which way, by idle timeout or explicit request)
> - After resume, the AppVM has lost the device, but dom0 has it connected.
> - Any attempt to have qubes disconnect the device results in errors in libxl
>
> I know this is not a complete report, I just want to know what kind of debug I can enable on qvm-block or the Qubes VM Manager itself, and if there is any kernel or xen options that will provide useful info.

During system suspend, USB drivers are unloaded by default. This is
because in many cases suspend would hang. This is equivalent to
physically removing connected device, at least from drivers point of
view. As such, it qualifies as "removing the device before detaching it
from the VM" described here:
https://www.qubes-os.org/doc/usb/

Warning: Do not remove the device before detaching it from the VM!
Otherwise, you will not be able to attach it anywhere later. See issue
1082 for details.

There is manual recovery procedure:
https://www.qubes-os.org/doc/usb/#what-if-i-removed-the-device-before-detaching-it-from-the-vm

List of modules to unload is here: /etc/qubes-suspend-module-blacklist
You can try removing ehci_pci from there and see if it breaks suspend on
your system.

- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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