--- Begin Message ---
Package: autopkgtest
Version: 3.17.2
Severity: wishlist
Tags: patch
Hello Martin,
as per our discussion on the autopkgtest mailing list [1], I'd like to
be able to have autopkgtest support nested VMs for testing of network
clients in the kernel such as NFS, CIFS, iSCSI, NBD, etc.
The logic would be to
- have the test environment run a simple server that the client may
connect to
- have a copy of the qcow2 base image in the test environment
- create a QEMU/KVM VM in the test environment that then tests the
client (this can again be done with adt-run inside the test env)
I've attached two patches that implement the necessary changes to
autopkgtest. They are quire minimal in fact:
1. Have adt-virt-qemu add an additional drive to the VM that
maps (read-only) to the qcow2 base image (but without QEMU
interpreting the image, just passing it through via format=raw).
This allows the drive to be used as a base image, e.g.
qemu-img create -f qcow2 -b /dev/vdb overlay.img
(Running KVM on top of something like that works, btw., in case
you were wondering - you can easily try that by creating a loop
device, i.e. losetup --show -f base.img and then doing
adt-run ... --- adt-virt-qemu /dev/loopX.)
2. Have adt-virt-qemu provide an environment variable to the tests
so that they may make use of it. (ADT_QCOW2_BASEIMAGE)
3. Have adt-virt-qemu export the capability provides-qcow2-baseimage.
4. Add new restriction needs-qcow2-baseimage that is checked against
that capability. (The base image logic is done unconditionally by
adt-virt-qemu, regardless of the restriction. In principle this
would allow people to just do vmdebootstrap inside the VM if the
base image were not to be exported.)
5. If in KVM mode, add -cpu host option to the emulator command, since
that is required (but not sufficient) for nested KVM to work.
Note that nested KVM will also require a module option to be set.
(nested=1 for either the kvm_intel or kvm_amd module.) Setting
-cpu host has no negative side effects even if nested=0 is set on
the host - then the kvm_* modules will not load in the VM and KVM
will simply be not available - same as without -cpu host.
On the other hand, nested KVM is nice-to-have, but not required for
a nested VM - the VM inside could be a non-accelerated QEMU VM.
Once could in principle also add support for nested KVM to adt-virt-lxc
by simply allowing the administrator to specify an additional qcow2
base image on the command line. That could be done in an additional
step.
I've updated the documentation to reflect the base image changes.
It would be great if that could be added to autopkgtest.
Thanks!
Regards,
Christian
From d091f958e1a61cbf4d3296c4267d011ba3c6dbd4 Mon Sep 17 00:00:00 2001
From: Christian Seiler <[email protected]>
Date: Sun, 4 Oct 2015 12:25:39 +0200
Subject: [PATCH 1/2] Add 'needs-qcow2-baseimage' restriction
Add restrictions that allows tests to require a qcow2 base image be
present inside the test environment, so that e.g. nested VM tests are
possible.
---
doc/README.package-tests.rst | 20 ++++++++++++++++++++
lib/testdesc.py | 9 ++++++++-
virt-subproc/adt-virt-qemu | 25 ++++++++++++++++++++++---
virt-subproc/adt-virt-qemu.1 | 10 ++++++++++
4 files changed, 60 insertions(+), 4 deletions(-)
diff --git a/doc/README.package-tests.rst b/doc/README.package-tests.rst
index e1127cb..5872617 100644
--- a/doc/README.package-tests.rst
+++ b/doc/README.package-tests.rst
@@ -202,6 +202,26 @@ needs-recommends
Enable installation of recommended packages in apt for the test
dependencies. This does not affect build dependencies.
+needs-qcow2-baseimage
+ The test needs to have a read-only qcow2 base image available so it
+ may create an overlay and start a qemu/KVM virtual machine inside
+ the test environment.
+
+ This is useful for testing network client packages that require
+ kernel support (NFS, CIFS, iSCSI, NBD, etc.): the external testing
+ environment sets up a minimalistic server environment and then
+ starts a virtual machine that tests the client.
+
+ While currently only adt-virt-qemu supports this, this options is
+ independent of the isolation level. If the setup of the server also
+ needs a specific isolation level, that should be specified
+ additionally.
+
+ The environment variable ADT_QCOW2_BASEIMAGE will be set to the
+ absolute path of the qcow2 base image. If the test environment
+ supports it, this variable will be available irrespective of
+ whether this restriction was added to the test or not.
+
Defined features
----------------
diff --git a/lib/testdesc.py b/lib/testdesc.py
index 260b2fa..33fdb7f 100644
--- a/lib/testdesc.py
+++ b/lib/testdesc.py
@@ -42,7 +42,8 @@ import adtlog
known_restrictions = ['rw-build-tree', 'breaks-testbed', 'needs-root',
'build-needed', 'allow-stderr', 'isolation-container',
- 'isolation-machine', 'needs-recommends']
+ 'isolation-machine', 'needs-recommends',
+ 'needs-qcow2-baseimage']
class Unsupported(Exception):
@@ -161,6 +162,12 @@ class Test:
'Test needs root on testbed which is not '
'available')
+ if 'needs-qcow2-baseimage' in self.restrictions and \
+ 'provides-qcow2-baseimage' not in caps:
+ raise Unsupported(self.name,
+ 'Test needs qcow2 testimage inside testbed which '
+ 'is not available')
+
#
# Parsing for Debian source packages
#
diff --git a/virt-subproc/adt-virt-qemu b/virt-subproc/adt-virt-qemu
index 6e3989a..2bed237 100755
--- a/virt-subproc/adt-virt-qemu
+++ b/virt-subproc/adt-virt-qemu
@@ -80,6 +80,8 @@ def parse_args():
help='Enable debugging output')
parser.add_argument('--qemu-options',
help='Pass through arguments to QEMU command.')
+ parser.add_argument('--nested-qcow2-baseimage',
+ help='qcow2 VM base image for use inside the VM (nested VMs)')
parser.add_argument('image', nargs='+',
help='disk image to add to the VM (in order)')
@@ -87,6 +89,8 @@ def parse_args():
if args.debug:
adtlog.verbosity = 2
+ if args.nested_qcow2_baseimage == None and len(args.image) == 1:
+ args.nested_qcow2_baseimage = args.image[0]
def prepare_overlay():
@@ -274,6 +278,10 @@ EOF
def make_auxverb(shared_dir):
'''Create auxverb script'''
+ envvars = ''
+ if args.nested_qcow2_baseimage != None:
+ envvars += 'export ADT_QCOW2_BASEIMAGE=/dev/vd%c ; ' % chr(ord('a') + len(args.image))
+
auxverb = os.path.join(workdir, 'runcmd')
with open(auxverb, 'w') as f:
f.write('''#!%(py)s
@@ -340,7 +348,8 @@ t_stderr.start()
s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
s.connect('%(tty)s')
cmd = '/bin/eofcat %%(d)s/stdin_eof %%(d)s/exit.tmp < %%(d)s/stdin | ' \\
- '(%%(c)s >> %%(d)s/stdout 2>> %%(d)s/stderr; echo $? > %%(d)s/exit.tmp);' \\
+ '(%(envvars)s ' \\
+ '%%(c)s >> %%(d)s/stdout 2>> %%(d)s/stderr; echo $? > %%(d)s/exit.tmp);' \\
'mv %%(d)s/exit.tmp %%(d)s/exit\\n' %% \\
{'d': job_guest, 'c': ' '.join(map(pipes.quote, sys.argv[1:]))}
s.send(cmd.encode())
@@ -369,7 +378,8 @@ t_stdin.join()
t_stdout.join()
t_stderr.join()
sys.exit(rc)
-''' % {'py': sys.executable, 'tty': os.path.join(workdir, 'ttyS1'), 'dir': shared_dir})
+''' % {'py': sys.executable, 'tty': os.path.join(workdir, 'ttyS1'), 'dir': shared_dir,
+ 'envvars' : envvars})
os.chmod(auxverb, 0o755)
@@ -475,6 +485,13 @@ def hook_open():
for i, image in enumerate(args.image[1:]):
argv.append('-drive')
argv.append('file=%s,if=virtio,index=%i,readonly' % (image, i + 1))
+ if args.nested_qcow2_baseimage != None:
+ # export base image as drive (it's the easiest way to get
+ # it into QEMU), but make sure format=raw is set, because
+ # we want the VM to be able to see it as a qcow2 image and
+ # not have QEMU interpret it
+ argv.append('-drive')
+ argv.append('file=%s,if=virtio,index=%i,readonly,format=raw' % (args.nested_qcow2_baseimage, len(args.image)))
if os.path.exists('/dev/kvm'):
argv.append('-enable-kvm')
@@ -550,13 +567,15 @@ def hook_forked_inchild():
def hook_capabilities():
- global normal_user
+ global normal_user, args
caps = ['revert', 'revert-full-system', 'root-on-testbed',
'isolation-machine', 'reboot']
# disabled, see hook_downtmp()
# caps.append('downtmp-host=%s' % os.path.join(workdir, 'shared', 'tmp'))
if normal_user:
caps.append('suggested-normal-user=' + normal_user)
+ if args.nested_qcow2_baseimage != None:
+ caps.append('provides-qcow2-baseimage')
return caps
diff --git a/virt-subproc/adt-virt-qemu.1 b/virt-subproc/adt-virt-qemu.1
index 0c5718f..19f2f1d 100644
--- a/virt-subproc/adt-virt-qemu.1
+++ b/virt-subproc/adt-virt-qemu.1
@@ -97,6 +97,16 @@ Enable debugging output.
.BI "--qemu-options=" arguments
Pass through arguments to QEMU command; e. g. --qemu-options='-readconfig qemu.cfg'
+.TP
+.BI "--nested-qcow2-baseimage=" image
+Base image (in qcow2 format) that is passed through to the VM in read-only
+mode. It may then be used by the container to create an overlay qcow2 image on
+top of it and start a nested VM. If there is only one image specified to
+.BR adt-virt-qemu ,
+this option defaults to that image. If there is more one image specified, it
+doesn't have a default value, so the option should be specified if running
+tests that require nested VMs is to be supported.
+
.SH CONFIGURATION FILES
If you use lots of options or images, you can put parts of, or the whole
command line into a text file, with one line per option. E. g. you can create a
--
2.1.4
From 11703001b3e9c4c4af87e838a8d30f523fdf9b39 Mon Sep 17 00:00:00 2001
From: Christian Seiler <[email protected]>
Date: Sun, 4 Oct 2015 13:11:06 +0200
Subject: [PATCH 2/2] adt-virt-qemu: emulate host-type CPU
In order to make nested KVM work, the emulated CPU needs to support
virtualization. The easiest way to do that that doesn't require lots of
compatibility checks is to tell QEMU to emulate the host CPU. This will
only work in KVM mode, so only enable it there.
This does not guarantee that nested KVM will work (the host's KVM
module has to have the appropriate option set), but it is required.
---
virt-subproc/adt-virt-qemu | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/virt-subproc/adt-virt-qemu b/virt-subproc/adt-virt-qemu
index 2bed237..85e7bbd 100755
--- a/virt-subproc/adt-virt-qemu
+++ b/virt-subproc/adt-virt-qemu
@@ -495,6 +495,10 @@ def hook_open():
if os.path.exists('/dev/kvm'):
argv.append('-enable-kvm')
+ # emulate host CPU so that nested KVM might work (if it's
+ # enabled)
+ argv.append('-cpu')
+ argv.append('host')
# pass through option to qemu
if args.qemu_options:
--
2.1.4
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