Currently, we have one huge function to construct qemu command line.
This is very ineffective esp. if there's a fault somewhere.

example: qemu ${otherargs} \
             -vnc 127.0.0.1:0,share=allow-exclusive

QEMU_CAPS_VNC_SHARE_POLICY (qemu >= 1.1)

Commit f60a50c7 intended to remove the warning only, but not with
the "return 0" together.

In 84c59ffa I've tried to fix changing ejectable media process. The
process should go like this:

1) we need to call 'eject' on the monitor
2) we should wait for 'DEVICE_TRAY_MOVED' event
3) now we can issue 'change' command

However, while waiting in step 2) the domain monitor was locked. So
even if qemu reported the desired event, the proper callback was not
called immediately. The monitor handling code needs to lock the
monitor in order to read the event. So that's the first lock we must
not hold while waiting. The second one is the domain lock. When
monitor handling code reads an event, the appropriate callback is
called then. The first thing that each callback does is locking the
corresponding domain as a domain or its device is about to change
state. So we need to unlock both monitor and VM lock. Well, holding
any lock while sleep()-ing is not the best thing to do anyway.

Since 0d70656a, it starts to access the sysfs files to build
the qemu command line (by virSCSIDeviceGetSgName, which is to find
out the scsi generic device name by adpater:bus:target:unit), there
is no way to work around, qemu wants to see the scsi generic device
like "/dev/sg6" anyway.

And there might be other places which need to access sysfs files
when building qemu command line in future.

Instead of increasing the arguments of qemuBuildCommandLine, this
introduces a new callback for qemuBuildCommandLine, and thus tests
can register their own callbacks for sysfs test input files accessing.

* src/qemu/qemu_command.h: (New callback struct
                            qemuBuildCommandLineCallbacks;
                            extern buildCommandLineCallbacks)
* src/qemu/qemu_command.c: (wire up the callback struct)
* src/qemu/qemu_driver.c: (Use the new syntax of qemuBuildCommandLine)
* src/qemu/qemu_hotplug.c: Likewise
* src/qemu/qemu_process.c: Likewise
* tests/testutilsqemu.[ch]: (Helper testSCSIDeviceGetSgName;
                             callback struct testCallbacks;)
* tests/qemuxml2argvtest.c: (Use testCallbacks)
* src/tests/qemuxmlnstest.c: (Like above)

Resolves:https://bugzilla.redhat.com/show_bug.cgi?id=927620

 #kill -STOP `pidof qemu-kvm`
 #virsh destroy $guest --graceful
 error: Failed to destroy domain testVM
 error: An error occurred, but the cause is unknown

With --graceful, SIGTERM always is emitted to kill driver
process, but it won't success till burning out waiting time
in case of process being stopped.
But domain destroy without --graceful can work, SIGKILL will
be emitted to the stopped process after 10 secs which always
kills a process even one that is currently stopped.
So report an error after burning out waiting time in this case.

Just like previous patches, this changes qemuCheckSharedDisk
into qemuCheckSharedDevice, which takes a virDomainDeviceDefPtr
argument instead.

Change bbe97ae9 caused the
QEMU driver to ignore ENOENT errors from cgroups, in order
to cope with missing /proc/cgroups. This is not good though
because many other things can cause ENOENT and should not
be ignored. The callers expect to see ENXIO when cgroups
are not present, so adjust the code to report that errno
when /proc/cgroups is missing
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Commit 632f78ca introduced a regression which causes schedinfo being
unable to set some parameters.  When migrating to priv->cgroup there
was missing variable left out and due to passed NULL to underlying
function, the setting failed.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=963592

Just like what previous patches do, it refactors qemuSetUnprivSGIO
to take the virDomainDeviceDefPtr as argument instead.

unpriv_sgio setting is tight with the shared device helpers, let's
put them together in qemu_conf.c

SCSI host device will also support "sgio", and perhaps we could
use "sgio" in other places too in future, renaming the enum to
reuse.

This adds the shared device entry when starting domain (more
exactly, when preparing host devices), and remove the entry
when destroying domain (when reattaching host devices).

This changes the helpers qemu{Add,Remove}SharedDisk into
qemu{Add,Remove}SharedDevice, as most of the code in the helpers
can be reused for scsi host device.

To track the shared scsi host device, first it finds out the
device path (e.g. /dev/s[dr]*) which is mapped to the sg device,
and use device ID of the found device path (/dev/s[dr]*) as the
hash key. This is because of the device ID is not unique between
between /dev/s[dr]* and /dev/sg*, e.g.

% sg_map
/dev/sg0  /dev/sda
/dev/sg1  /dev/sr0

% ls -l /dev/sda
brw-rw----. 1 root disk 8, 0 May  2 19:26 /dev/sda

%ls -l /dev/sg0
crw-rw----. 1 root disk 21, 0 May  2 19:26 /dev/sg0

"Shared disk" is not only the thing we should care about after "scsi
hostdev" is introduced. A same scsi device can be used as "disk" for
one domain, and as "scsi hostdev" for another domain at the same time.
That's why this patch renames qemu_driver->sharedDisks. Related functions
and structs are also renamed.

Commit 7f15ebc7 introduced a bug
happening when guests without a <graphics> element are migrated.
The initialization of listenAddress happens unconditionally
from the cookie even if the cookie->graphics pointer was NULL.
Moved the initialization to where it is safe.
Signed-off-by: NViktor Mihajlovski <mihajlov@linux.vnet.ibm.com>

QEMU introduced "discard" option for drive since commit a9384aff53,

<...>
@var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and
controls whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap})
requests are ignored or passed to the filesystem.  Some machine types
may not support discard requests.
</...>

This patch exposes the support in libvirt.

QEMU supported "discard" for "-drive" since v1.5.0-rc0:

% git tag --contains a9384aff53
contains
v1.5.0-rc0
v1.5.0-rc1

So this only detects the capability bit using virQEMUCapsProbeQMPCommandLine.

During building of the qemu command line determine whether to add/use the
'-no-reboot' option only if each of the 'on' events want to to destroy
the domain; otherwise, use the '-no-shutdown' option.

Prior to this change both could be on the command line, which while allowed
could be construed as a conflict.

Adding a VNC WebSocket support for QEMU driver.  This functionality is
in upstream qemu from commit described as v1.3.0-982-g7536ee4, so the
capability is being recognized based on QEMU version for now.

QEMU introduced command line "-mem-merge=on|off" (defaults to on) to
enable/disable the memory merge (KSM) at guest startup. This exposes
it by new XML:
  <memoryBacking>
    <nosharepages/>
  </memoryBacking>

The XML tag is same with what we used internally for old RHEL.

* src/qemu/qemu_capabilities.h: New capability bit.
* src/qemu/qemu_capabilities.c (virQEMUCapsProbeQMPCommandLine): New
function, based on qemuMonitorGetCommandLineOptionParameters, which was
introduced by commit bd56d0d8; use it to set new capability bit.
(virQEMUCapsInitQMP): Use new function.

The QEMU command line syntax for RBD disks is

   file=rbd:pool/image:opt1=val1:opt2=val2...

There is no way to escape the ':' if it appears in the
pool or image name. Thus it must be explicitly forbidden
if it occurs in the libvirt XML. People are known to
be abusing the lack of escaping in current libvirt to
pass arbitrary args to QEMU.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

Commit bd56d0d8 could lead to freeing an uninitialized pointer:

qemu/qemu_monitor_json.c: In function 'qemuMonitorJSONGetCommandLineOptionParameters':
qemu/qemu_monitor_json.c:4284: warning: 'cmd' may be used uninitialized in this function

* src/qemu/qemu_monitor_json.c
(qemuMonitorJSONGetCommandLineOptionParameters): Initialize variable.
Signed-off-by: NEric Blake <eblake@redhat.com>

Ever since the conversion to using only QMP for probing features
of qemu 1.2 and newer, we have been unable to detect features
that are added only by additional command line options.  For
example, we'd like to know if '-machine mem-merge=on' (added
in qemu 1.5) is present.  To do this, we will take advantage
of qemu 1.5's query-command-line-parameters QMP call [1].

This patch wires up the framework for probing the command results;
if the QMP command is missing, or if a particular command line
option does not output any parameters (for example, -net uses
a polymorphic parser, which showed up as no parameters as of qemu
1.5), we silently treat that command as having no results.

[1] https://lists.gnu.org/archive/html/qemu-devel/2013-04/msg05180.html

* src/qemu/qemu_monitor.h (qemuMonitorGetOptions)
(qemuMonitorSetOptions)
(qemuMonitorGetCommandLineOptionParameters): New functions.
* src/qemu/qemu_monitor_json.h
(qemuMonitorJSONGetCommandLineOptionParameters): Likewise.
* src/qemu/qemu_monitor.c (_qemuMonitor): Add cache field.
(qemuMonitorDispose): Clean it.
(qemuMonitorGetCommandLineOptionParameters): Implement new function.
* src/qemu/qemu_monitor_json.c
(qemuMonitorJSONGetCommandLineOptionParameters): Likewise.
(testQemuMonitorJSONGetCommandLineParameters): Test it.
Signed-off-by: NEric Blake <eblake@redhat.com>

No need to open code a string list cleanup, if we are nice
to the caller by guaranteeing a NULL-terminated result.

* src/qemu/qemu_monitor_json.c (qemuMonitorJSONGetCPUDefinitions)
(qemuMonitorJSONGetCommands, qemuMonitorJSONGetEvents)
(qemuMonitorJSONGetObjectTypes, qemuMonitorJSONGetObjectProps):
Use simpler cleanup.
Signed-off-by: NEric Blake <eblake@redhat.com>

Follows on the heels of other bool cleanups, such as commit 93002b98.

* src/qemu/qemu_monitor.h (qemuMonitorOpen, qemuMonitorOpenFD):
Update json parameter type.
* src/qemu/qemu_monitor.c (qemuMonitorOpen, qemuMonitorOpenFD):
Likewise.
(_qemuMonitor): Adjust field type.
* src/qemu/qemu_domain.h (_qemuDomainObjPrivate): Likewise.
* src/qemu/qemu_domain.c (qemuDomainObjPrivateXMLParse): Adjust
client.
* src/qemu/qemu_process.c (qemuProcessStart): Likewise.
* tests/qemumonitortestutils.c (qemuMonitorTestNew): Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>

This adds both attachment and detachment support for scsi host
device.
Signed-off-by: NHan Cheng <hanc.fnst@cn.fujitsu.com>
Signed-off-by: NOsier Yang <jyang@redhat>

Found that I was unable to start existing domains after updating
to a kernel with no cgroups support

  # zgrep CGROUP /proc/config.gz
  # CONFIG_CGROUPS is not set
  # virsh start test
  error: Failed to start domain test
  error: Unable to initialize /machine cgroup: Cannot allocate memory

virCgroupPartitionNeedsEscaping() correctly returns errno (ENOENT) when
attempting to open /proc/cgroups on such a system, but it was being
dropped in virCgroupSetPartitionSuffix().

Change virCgroupSetPartitionSuffix() to propagate errors returned by
its callees.  Also check for ENOENT in qemuInitCgroup() when determining
if cgroups support is available.

It's better to put the usb related codes into qemuDomainAttachHostUsbDevice
instead of qemuDomainAttachHostDevice.

And in the old qemuDomainAttachHostDevice, just stealing the "usb" from
driver->activeUsbHostdevs leaks the memory.

Although virtio-scsi supports SCSI PR (Persistent Reservations),
the device on host may do not support it. To avoid losing data,
Just like PCI and USB pass through devices, only one live guest
is allowed per SCSI host pass through device."
Signed-off-by: NHan Cheng <hanc.fnst@cn.fujitsu.com>