Long lines are harder to read and harder to diff; in fact, if lines get
too long (> 1000 bytes), it starts causing issues where git send-email
refuses to send patches for the file.  I've cleaned up the tests
directory in the past (see commits bd6c46fa, 3b750d13), but new long
lines have been introduced in the meantime.

Why 90 instead of 80? Because there were too many tests on the fringe
edge, and I didn't want to edit that many files.

Add a syntax check to prevent future long lines.

* cfg.mk (sc_prohibit_long_lines): New rule.
* tests/qemuxml2argvdata/qemuxml2argv-*.args: Split lines of any
file with content longer than 90 columns.
* tests/storagevolxml2argvdata/*.argv: Likewise.
Signed-off-by: NEric Blake <eblake@redhat.com>

Several tests assume that VNC is always available and include it in
their configs and the expected command line. The tests have nothing to
do with graphics display so they shouldn't rely on VNC.

 This patch adds a new attribute "rawio" to the "disk" element
 of domain XML. Valid values of "rawio" attribute are "yes"
 and "no".
 rawio='yes' indicates the disk is desirous of CAP_SYS_RAWIO.

 If you specify the following XML:

 <disk type='block' device='lun' rawio='yes'>
  ...
 </disk>

 the domain will be granted CAP_SYS_RAWIO.
 (of course, the domain have to be executed with root privilege)

NOTE:
   - "rawio" attribute is only valid when device='lun'
   - At the moment, any other disks you won't use rawio can use rawio.
Signed-off-by: NTaku Izumi <izumi.taku@jp.fujitsu.com>

In the past, generic SCSI commands issued from a guest to a virtio
disk were always passed through to the underlying disk by qemu, and
the kernel would also pass them on.

As a result of CVE-2011-4127 (see:
http://seclists.org/oss-sec/2011/q4/536), qemu now honors its
scsi=on|off device option for virtio-blk-pci (which enables/disables
passthrough of generic SCSI commands), and the kernel will only allow
the commands for physical devices (not for partitions or logical
volumes). The default behavior of qemu is still to allow sending
generic SCSI commands to physical disks that are presented to a guest
as virtio-blk-pci devices, but libvirt prefers to disable those
commands in the standard virtio block devices, enabling it only when
specifically requested (hopefully indicating that the requester
understands what they're asking for). For this purpose, a new libvirt
disk device type (device='lun') has been created.

device='lun' is identical to the default device='disk', except that:

1) It is only allowed if bus='virtio', type='block', and the qemu
   version is "new enough" to support it ("new enough" == qemu 0.11 or
   better), otherwise the domain will fail to start and a
   CONFIG_UNSUPPORTED error will be logged).

2) The option "scsi=on" will be added to the -device arg to allow
   SG_IO commands (if device !='lun', "scsi=off" will be added to the
   -device arg so that SG_IO commands are specifically forbidden).

Guests which continue to use disk device='disk' (the default) will no
longer be able to use SG_IO commands on the disk; those that have
their disk device changed to device='lun' will still be able to use SG_IO
commands.

*docs/formatdomain.html.in - document the new device attribute value.
*docs/schemas/domaincommon.rng - allow it in the RNG
*tests/* - update the args of several existing tests to add scsi=off, and
 add one new test that will test scsi=on.
*src/conf/domain_conf.c - update domain XML parser and formatter

*src/qemu/qemu_(command|driver|hotplug).c - treat
 VIR_DOMAIN_DISK_DEVICE_LUN *almost* identically to
 VIR_DOMAIN_DISK_DEVICE_DISK, except as indicated above.

Note that no support for this new device value was added to any
hypervisor drivers other than qemu, because it's unclear what it might
mean (if anything) to those drivers.

In some versions of qemu, both virtio-blk-pci and virtio-net-pci
devices can have an event_idx setting that determines some details of
event processing. When it is enabled, it "reduces the number of
interrupts and exits for the guest". qemu will automatically enable
this feature when it is available, but there may be cases where this
new feature could actually make performance worse (NB: no such case
has been found so far).

As a safety switch in case such a situation is encountered in the
field, this patch adds a new attribute "event_idx" to the <driver>
element of both disk and interface devices. event_idx can be set to
"on" (to force event_idx on in case qemu has it disabled by default)
or "off" (for force event_idx off). In the case that event_idx support
isn't present in qemu, the attribute is ignored (this on the advice of
the qemu developer).

docs/formatdomain.html.in: document the new flag (marking it as
   "don't mess with this!"
docs/schemas/domain.rng: add event_idx in appropriate places
src/conf/domain_conf.[ch]: add event_idx to parser and formatter
src/libvirt_private.syms: export
   virDomainVirtioEventIdx(From|To)String
src/qemu/qemu_capabilities.[ch]: detect and report event_idx in
   disk/net
src/qemu/qemu_command.c: add event_idx parameter to qemu commandline
    when appropriate.
tests/qemuxml2argvdata/qemuxml2argv-event_idx.args,
tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml,
tests/qemuxml2argvtest.c,
tests/qemuxml2xmltest.c: test cases for event_idx.

For virtio disks and interfaces, qemu allows users to enable or disable
ioeventfd feature. This means, qemu can execute domain code, while
another thread waits for I/O event. Basically, in some cases it is win,
in some loss. This feature is available via 'ioeventfd' attribute in disk
and interface <driver> element. It accepts 'on' and 'off'. Leaving this
attribute out defaults to hypervisor decision.