Implement a compressed save image format for qemu.  While ideally
we would have the choice between compressed/non-compressed
available to the libvirt API, unfortunately there is no "flags"
parameter to the virDomainSave() API.  Therefore, implement this
as a qemu.conf option.  gzip, bzip2, and lzma are implemented, and
it should be very easy to implement additional compression
methods.

One open question is if/how we should detect the compression
binaries.  One way to do it is to do compile-time setting of the
paths (via configure.in), but that doesn't seem like a great thing
to do.  My preferred solution is not to detect at all;
when we go to run the commands that need them, if they
aren't available, or aren't available in one of the standard paths,
then we'll fail.  That's also the solution implemented in this patch.

In the future, we'll have a more robust (managed) save/restore API,
at which time we can expose this functionality properly in the API.

V2: get rid of redundant dd command and just use >> to append data.
V3: Add back the missing pieces for the enum and bumping the save version.
V4: Make the compressed field in the save_header an int.
    Implement LZMA compression.
Signed-off-by: NChris Lalancette <clalance@redhat.com>

If a PCI device reset causes other devices to be reset, allow it so long
as those other devices are note assigned to another active domain.

Note, we need to take the driver lock qemudNodeDeviceReset() because the
check function will iterate over the domain list.

* src/qemu_conf.c: add qemuCheckPciHostDevice() to iterate over active
  domains checking whether the affected device is assigned

* src/pci.[ch]: add pciDeviceEquals() helper

When using a Secondary Bus Reset, all devices on the bus are reset.

Extend the pciResetDevice() API so that a 'check' callback can be
supplied which will verify that it is safe to reset the other devices
on the bus.

The virDomainObjPtr parameter is needed so that when the check function
iterates over the domain list, it can avoid double locking.

* src/pci.[ch]: add a 'check' callback to pciResetDevice(), re-work
  pciIterDevices() to pass the check function to the iter functions,
  use the check function in the bus iterator, return the first unsafe
  device from pciBusCheckOtherDevices() and include its details in
  the bus reset error message.

* src/qemu_driver.c, src/xen_uninified.c: just pass NULL as the
  check function for now

Currently, if we are unable to reset a PCI device we return a fairly
generic 'No PCI reset capability available' error message.

Fix that by returning an error from the individual reset messages and
using that error to construct the higher level error mesage.

* src/pci.c: set errors in pciTryPowerManagementReset() and
  pciTrySecondaryBusReset() on failure; use those error messages
  in pciResetDevice(), or explain that no reset support is available

When the guest shuts down, we should attempt to restore all PCI host
devices to a sane state.

In the case of managed hostdevs, we should reset and re-attach the
devices. In the case of unmanaged hostdevs, we should just reset them.

Note, KVM will already reset assigned devices when the guest shuts
down using whatever means it can, so we are only doing it to cover the
cases the kernel can't handle.

* src/qemu_driver.c: add qemuDomainReAttachHostDevices() and call
  it from qemudShutdownVMDaemon()

Attaching a host PCI device to a qemu guest is done with a
straightforward 'pci_add auto host host=XX:XX.X' command.

Like with NIC and disk hotplug, we need to retain the guest PCI address
assigned by qemu so that we can use it for hot-unplug.

Identifying a device for detach is done using the host PCI address.

Managed mode is handled by detaching/resetting the device before
attaching it to the guest and re-attaching it after detaching it from
the guest.

* src/qemu_driver.c: add qemudDomainAttachHostPciDevice() and
  qemudDomainDetachHostPciDevice()

* src/domain_conf.h: add somewhere to store the guest PCI address

* src/domain_conf.c: handle formatting and parsing the guest PCI
  address

Re-factor the hostdev hotplug code so that we can easily add PCI
hostdev hotplug to qemudDomainAttachHostDevice().

* src/qemu_driver.c: rename qemudDomainAttachHostDevice() to
  qemudDomainAttachHostUsbDevice(); make qemudDomainAttachHostDevice()
  handle all hostdev types

* src/libvirt_private.syms: export a couple of hostdev related
  ToString() functions

As of qemu 0.10.6, qemu now honors the -S flag on incoming migration.
That means that when the migration completes, we have to issue a
'cont' command to get the VM running again.  We do it unconditionally
since it won't hurt on older qemu.
Signed-off-by: NChris Lalancette <clalance@redhat.com>

When doing a restore, we were forgetting to update the state file
for the VM.  That means that if you do a save/restore, then shut
down libvirtd, then start it back up, you'll see the state of the
guest as "paused", even though it is really running.  We were
just forgetting a "virDomainSaveStatus" call in the restor path.
Signed-off-by: NChris Lalancette <clalance@redhat.com>

If we're running qemu unprivileged, we need to chown any supplied kernel
or initrd before spawning it.

* src/qemu_driver.c: rename qemuDomainSetDiskOwnership() to
  qemuDomainSetFileOwnership(), pass it a path string instead of a disk
  definition and use it for chowning the kernel/initrd in
  qemuDomainSetAllDeviceOwnership()

Signed-off-by: NChris Lalancette <clalance@redhat.com>

Signed-off-by: NChris Lalancette <clalance@redhat.com>

Signed-off-by: NChris Lalancette <clalance@redhat.com>

Signed-off-by: NChris Lalancette <clalance@redhat.com>

Fix up qemudDomainMigratePrepare2 to use virGetHostname instead of
gethostname.  Besides the fact that virGetHostname is far more clever,
there was a latent bug in the handling that could cause a buffer overflow
on a very long hostname.
Signed-off-by: NChris Lalancette <clalance@redhat.com>

* src/qemu_driver.c: Check that monitor device is not NULL
  before runing a command to protect against bugs in caller

* src/qemu_driver.c: Add check that QEMU is active before attemting
  to shutdown. Fix error code for check in destroy method

* src/util.c: Don't drop capabilities until after the PID file has
  been written. Kill off child if writing the PID file fails
* src/qemu_driver.c: Remove bogus trailing '/' in state dir

* src/qemu_driver.c: fix qemudOpenMonitorUnix() to retry on ENOENT
  instead of EACCES which is the error one receive when the socket
  error hasn't shown up yet

* src/qemu_driver.c: implement missing features in qemudDomainGetVcpus
  for 'cpu' and 'cpuTime' fields

In order to hotplug a network/bridge backed NIC, we need to first create
the tap file descriptor, add the tap interface to the bridge and then
pass the file descriptor to the qemu process using the 'getfd' monitor
command.

Once the tapfd has been accepted, we create the network backend using
host_net_add, supplying the name assigned to the tapfd. If this fails,
we need to close the tapfd in qemu using the 'closefd' monitor command.

If the version of qemu does not support the getfd/closefd monitor
commands we detect "unknown command" in the getfd reply and fail the
attach operation.

* src/qemu_driver.c: add support for tapfd based hotplug in
  qemudDomainAttachNetDevice()

Add qemudMonitorCommandWithFd() which allows a file descriptor to be
sent to qemu over a unix monitor socket using SCM_RIGHTS. See the
unix(7) and cmsg(3) man pages.

* src/qemu_conf.c: add a scm_fd param to qemudMonitorCommandExtra(),
  add qemudMonitorCommandWithFd(), implement SCM_RIGHTS support in
  qemudMonitorSendUnix()

Switch from using write() to using sendmsg() on QEMU's monitor socket
so that we can add support for SCM_RIGHTS.

* src/qemu_driver.c: add sendmsg() based qemudMonitorSendUnix() and use
  it when the monitor fd is a unix socket

Add a little helper function to write the monitor command followed by
carriage return in a single write.

This doesn't make any real difference, but allows us to more easily
switch to using sendmsg() when using the monitor over a unix socket.

* src/qemu_conf.c: split qemudMonitorSend() out

In subsequent patches we're going to have a file descriptor to close
too, so centralize the error handling cleanups to make things easier.

* src/qemu_conf.c: in qemudDomainAttachNetDevice() consolidate the
  error handling cleanups together

With hotplug, we're going to want to pass a tapfd name rather than an
actual file descriptor, so prepare the way by passing a string tapfd to
qemuBuildHostNetStr().

* src/qemu_conf.h: qemuBuildHostNetStr() takes a string tapfd now

* src/qemu_conf.c: pass qemuBuildHostNetStr() a string rather than an
  actual file descriptor

* src/qemu_driver.c: update qemudDomainAttachNetDevice() for change

By probing for qemu machine types, we increased the time of a
GetCapabilities call from 100us to a whopping 60ms.

This patch takes the approach of only probing for machine types
when the mtime of the emulator binary changed since the last time
the capabilities were generated.

* src/capabilities.h: cache the emulator binary mtime

* src/qemu_conf.c: add qemudGetOldMachines() to copy the machine
  types from the old caps struct if the mtime for the binary hasn't
  changed

* src/qemu_conf.h, src/qemu_driver.c: pass the old caps pointer to
  qemudCapsInit()

Not all possible emulators are actually in the capabilities, so if we
don't find the supplied emulator we should probe it directly for machine
types.

* src/qemu_driver.c: add qemudCanonicalizeMachineDirect() to directly
  probe an emulator for the canonical machine type

In qemu-0.11 there is a 'pc-0.10' machine type which allows you to run
guests with a machine which is compatible with the pc machine in
qemu-0.10 - e.g. using the original PCI class for virtio-blk and
virtio-console and disabling MSI support in virtio-net. The idea here
is that we don't want to suprise guests by changing the hardware when
qemu is updated.

I've just posted some patches for qemu-0.11 which allows libvirt to
canonicalize the 'pc' machine alias to the latest machine version.

This patches makes us use that so that when a guest is configured to
use the 'pc' machine type, we resolve that to 'pc-0.11' machine and
save that in the guest XML.

See also:

  https://fedoraproject.org/wiki/Features/KVM_Stable_Guest_ABI

* src/qemu_conf.c: add qemudCanonicalizeMachine() to canonicalize
  the machine type according to the machine aliases in capabilities

* src/qemu_driver.c: parse aliases in qemudParseMachineTypesStr()

Do the check in libvirt.c, to save drivers from the burden. This changes
behavior slightly in the qemu driver: we no longer explictly error if
passed an empty string. An error will still be thrown when the device
lookup fails.

 * qemud/libvirtd_qemu.aug, qemud/test_libvirtd_qemu.aug,
   src/qemu.conf: Add 'cgroups_controllers' and 'cgroups_device_acl'
   parameters
 * src/qemu_conf.h, src/qemu_conf.c: Load & parse configuration params
   for cgroups
 * src/qemu_driver.c: Only use cgroups controllers that are activated,
   and use configured device whitelist instead of default, if set.

* src/qemu_driver.c: Set a restrictive block device whitelist for
  all QEMU guests. Update whitelist when hotplugging disks.
* src/cgroup.h, src/cgroup.c: Add some more convenience methods
  for dealing with block device whitelists.

* src/qemu_driver.c:  Add driver methods qemuGetSchedulerType,
  qemuGetSchedulerParameters, qemuSetSchedulerParameters
* src/lxc_driver.c: Fix to use unsigned long long consistently
  for schedular parameters
* src/cgroup.h, src/cgroup.c: Fix cpu_shares to take unsigned
  long long
* src/util.c, src/util.h, src/libvirt_private.syms: Add a
  virStrToDouble helper
* src/virsh.c: Fix handling of --set arg to schedinfo command
  to honour the designated data type of each schedular tunable
  as declared by the driver

* src/qemu_driver.c: Place guest in cgroup upon startup. Remove
  cgroup upon shutdown

* src/datatypes.c src/domain_conf.c src/interface_conf.c
  src/lxc_driver.c src/qemu_driver.c src/storage_backend.c src/virsh.c:
  add bare %s format string to printf-derivatives called with no format
  string

* include/libvirt/libvirt.h include/libvirt/libvirt.h.in: adds the new
  flag VIR_MEMORY_PHYSICAL for virDomainMemoryPeek
* src/libvirt.c: update the front-end checking
* src/qemu_driver.c: extend the QEmu driver

qemu network devices are hot-unplugged in two stages - first the PCI NIC
is removed using 'pci_del <pci_addr>' and then the backend is removed
using 'host_net_remove <vlan> <name>'.

In order to perform these operations we need to have retained the
PCI address, backend name and vlan number.

* src/qemu_driver.c: add qemudDomainDetachNetDevice()

When we pci_add a NIC, we need to retain the PCI address assigned by
qemu for using during detach.

* src/qemu_driver.c: use qemudParsePciAddReply() to pull the PCI
  address from the pci_add reply

* src/domain_conf.c: handle storing and parsing the PCI address in the
  domain state XML file

The current code for parsing pci_add replies ignores the the domain and
bus numbers. Re-write the code to rectify that.

Also, since pci_add is used for NIC hotplug as well ask disk hotplug,
re-factor the code into a separate function.

* src/qemu_driver.c: add qemudParsePciAddReply() function which can
  handle parsing domain and bus numbers

If we fail to pci_add a NIC, we should remove the network backend and
leave things the way we found them. To do that, we pre-allocate a
host_net_remove monitor command and issue that if the pci_add fails.
If the remove fails, we just log a warning.

We can only do this if we have a name for the network backend and
we know the vlan number its associated with.

* src/qemu_driver.c: host_net_remove the network backend if the
  pci_add fails