The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform/crosvm/+/2056644c7d1cbe2cecca214ef4e96de6948b4945

commit 2056644c7d1cbe2cecca214ef4e96de6948b4945
Author: Dylan Reid <dgreid@chromium.org>
Date: Thu Apr 05 05:53:28 2018

crosvm: Allow disks to be specified as /proc/self/fd/X

Concierge needs to be able to pass open file descriptors to crosvm when
crosvm is executed. Use /proc/self/fd to communicate that a file is
already open. This will allow passing open FDs to concierge over D-BUS
and avoid giving the crosvm user permission to open files in different
parts of the system.

BUG=827705
TEST=Start VM with persistent storage on a USB device.

Change-Id: I1c56eeb11f95f32e235f3486eb04581851c41d90
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/991094
Reviewed-by: Zach Reizner <zachr@chromium.org>

[modify] https://crrev.com/2056644c7d1cbe2cecca214ef4e96de6948b4945/src/linux.rs

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/0142e4177712b24a53acdd6d5f9d98cebdf6a3d1

commit 0142e4177712b24a53acdd6d5f9d98cebdf6a3d1
Author: Dylan Reid <dgreid@chromium.org>
Date: Fri Apr 06 05:12:03 2018

vm_tools: Enable creation of disk images on USB/SD

Expand concierge_client to allow creating a qcow image on a USB stick or
SD Card. The concierge service can't perform this task because it isn't
allowed access to external media. However the client runs in crosh,
which can.

BUG=827705
TEST=run:
concierge_client --create_external_disk --removable_media="USB Drive"
--disk_size=2000000000 --name=test
on samus with VMs enabled.

Change-Id: Ic34193f4d4ebbdcae369506815ef68dc24cc56f4
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/992997
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>

[modify] https://crrev.com/0142e4177712b24a53acdd6d5f9d98cebdf6a3d1/vm_tools/host.gypi
[modify] https://crrev.com/0142e4177712b24a53acdd6d5f9d98cebdf6a3d1/vm_tools/concierge/client.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/628fa5670da52605a0a9bd4b03f36810db81c281

commit 628fa5670da52605a0a9bd4b03f36810db81c281
Author: Dylan Reid <dgreid@chromium.org>
Date: Fri Apr 06 05:12:04 2018

vm_tools: concierge: Support passing an FD to start

When starting a VM, accept an open file descriptor appended to the D-BUS
message. This FD will be used for the VM's persistent storage, enabling
VMs from locations other than /home/root/<user sha>.

BUG=827705
TEST=Start a VM with data on a USB stick.

Change-Id: I925ad956935331b3349d3e526dbf916a7bf42f52
Reviewed-on: https://chromium-review.googlesource.com/992998
Commit-Ready: Dylan Reid <dgreid@chromium.org>
Tested-by: Dylan Reid <dgreid@chromium.org>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>

[modify] https://crrev.com/628fa5670da52605a0a9bd4b03f36810db81c281/vm_tools/concierge/service.cc
[modify] https://crrev.com/628fa5670da52605a0a9bd4b03f36810db81c281/vm_tools/concierge/client.cc