Commit Graph

130 Commits

Author SHA1 Message Date
Andrea Bolognani
86a68bdb0c qemu: Permit PCI-free aarch64 mach-virt guests
There has been some progress lately in enabling virtio-pci on
aarch64 guests; however, guest OS support is still spotty at best,
so most guests are going to be using virtio-mmio instead.

Currently, mach-virt guests are closely modeled after q35 guests,
and that includes always adding a dmi-to-pci-bridge that's just
impossible to get rid of. While that's acceptable (if suboptimal)
for q35, where you will always need some kind of PCI device anyway,
mach-virt guests should be allowed to avoid it.
2016-06-17 18:30:04 +02:00
Laine Stump
d5fb8f4564 qemu: don't add pci-bridge to Q35/arm domains unless it's needed
Until now, a Q35 domain (or arm/virt, or any other domain that has a
pcie-root bus) would always have a pci-bridge added, so that there
would be a hotpluggable standard PCI slot available to plug in any PCI
devices that might be added. This patch removes the explicit add,
instead relying on the pci-bridge being auto-added during PCI address
assignment (it will add a pci-bridge if there are no free slots).

This doesn't eliminate the dmi-to-pci-bridge controller that is
explicitly added whether or not a standard PCI slot is required (and
that is almost never used as anything other than a converter between
pcie.0's PCIe slots and standard PCI). That will be done separately.
2016-06-16 13:48:25 -04:00
Martin Kletzander
d3c784999d conf: Add support of zero-detection for disks
This option allows or disallows detection of zero-writes if it is set to
"on" or "off", respectively.  It can be also set to "unmap" in which
case it will try discarding that part of image based on the value of the
"discard" option.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
2016-06-14 08:25:25 +02:00
Pavel Hrdina
c34ada0996 spice: introduce listen type none
This new listen type is currently supported only by spice graphics.
It's introduced to make it easier and clearer specify to not listen
anywhere in order to start a guest with OpenGL support.

The old way to do this was set spice graphics autoport='no' and don't
specify any ports.  The new way is to use <listen type='none'/>.  In
order to be able to migrate to old libvirt the migratable XML will be
generated without the listen element and with autoport='no'.  Also the
old configuration will be automatically converted to the this listen
type.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-06-09 14:44:08 +02:00
Pavel Hrdina
ffac505639 spice: introduce spice_auto_unix_socket config option
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-06-09 14:43:39 +02:00
Pavel Hrdina
e0c309b2dc spice: add support for listen type socket
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1335832

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-06-09 14:43:15 +02:00
Pavel Hrdina
acc83afe33 vnc: add support for listen type 'socket'
VNC graphics already supports sockets but only via 'socket' attribute.
This patch coverts that attribute into listen type 'socket'.

For backward compatibility we need to handle listen type 'socket' and 'socket'
attribute properly to support old XMLs and new XMLs.  If both are provided they
have to match, if only one of them is provided we need to be able to parse that
configuration too.

To not break migration back to old libvirt if the socket is provided by user we
need to generate migratable XML without the listen element and use only 'socket'
attribute.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-06-09 14:42:48 +02:00
Martin Kletzander
3484c05ce0 qemu: Add support to QXL's max_outputs parameter
Historically, we added heads=1 to videos, but for example for qxl, we
did not reflect that on the command line.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1283207

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
2016-06-07 12:42:54 +02:00
Laine Stump
4d100c7a41 conf: permit auto-assignment of controller indexes
Hand-entering indexes for 20 PCI controllers is not as tedious as
manually determining and entering their PCI addresses, but it's still
annoying, and the algorithm for determining the proper index is
incredibly simple (in all cases except one) - just pick the lowest
unused index.

The one exception is USB2 controllers because multiple controllers in
the same group have the same index. For these we look to see if 1) the
most recently added USB controller is also a USB2 controller, and 2)
the group *that* controller belongs to doesn't yet have a controller
of the exact model we're just now adding - if both are true, the new
controller gets the same index, but in all other cases we just assign
the lowest unused index.

With this patch in place and combined with the automatic PCI address
assignment, we can define a PCIe switch with several ports like this:

  <controller type='pci' model='pcie-root-port'/>
  <controller type='pci' model='pcie-switch-upstream-port'/>
  <controller type='pci' model='pcie-switch-downstream-port'/>
  <controller type='pci' model='pcie-switch-downstream-port'/>
  <controller type='pci' model='pcie-switch-downstream-port'/>
  <controller type='pci' model='pcie-switch-downstream-port'/>
  <controller type='pci' model='pcie-switch-downstream-port'/>
  ...

These will each get a unique index, and PCI addresses that connect
them together appropriately with no pesky numbers required.
2016-05-25 15:00:25 -04:00
Ján Tomko
72f652da63 conf: add <acpi><table> to <os>
Add a new element to <domain> XML:
<os>
  <acpi>
    <table type="slic">/path/to/acpi/table/file</table>
  </acpi>
</os>

To supply a path to a SLIC (Software Licensing) ACPI
table blob.

https://bugzilla.redhat.com/show_bug.cgi?id=1327537
2016-05-25 17:15:21 +02:00
Ján Tomko
b88f5f1af9 tests: remove <readonly/> from IDE disks
Read-only IDE disks are not supported, but the error
is raised only when QEMU_CAPS_DRIVE_READONLY is set.
2016-05-23 09:39:40 +02:00
Cole Robinson
f3d5e255cb tests: qemu: test <address type='pci'/> with aarch64
This is an interesting test case since PCI isn't the default for
aarch64.
2016-05-20 13:54:26 -04:00
Laine Stump
c026f8f1c2 qemu: auto-assign addresses when <address type='pci'/> is specified
Rather than only assigning a PCI address when no address is given at
all, also do it when the config says that the address type is 'pci',
but it gives no address (virDeviceInfoPCIAddressWanted()).

There are also several places after parsing but prior to address
assignment where code previously expected that any info with address
type='pci' would have a *valid* PCI address, which isn't always the
case - now we check not only for type='pci', but also for a valid
address (virDeviceInfoPCIAddressPresent()).

The test case added in this patch was directly copied from Cole's patch titled:

    qemu: Wire up address type=pci auto_allocate
2016-05-20 13:54:26 -04:00
Pavel Hrdina
2faa13560c tests: cleanup vnc auto socket test
Commit 55320c23 introduced a new test for VNC to test if
vnc_auto_unix_socket is set in qemu.conf, but forget to enable it in
qemuxml2argvtest.c.

This patch also moves the code in qemuxml2xmltest.c next to other VNC
tests and refactor the test so we also check the case for parsing active
XML.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-05-20 10:05:55 +02:00
Pavel Hrdina
ed7683f4d6 qemu_domain: add a empty listen type address if we remove socket for VNC
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-05-20 10:05:55 +02:00
Ján Tomko
936b86528d Remove DISK_BUS_XEN support from qemuBuildDiskDriveCommandLine
We have stopped supporting Xenner some time ago.
2016-05-20 09:02:08 +02:00
Andrea Bolognani
f6ececa68d tests: Try different usable GIC versions
The only case where the hardware capabilities influence the result
is when no <gic/> element was provided.

The test programs now ensure both that the correct GIC version is
picked in that case, and that hardware capabilities are not taken
into account when the user has already picked a GIC version.
2016-05-18 11:27:56 +02:00
Pavel Hrdina
b33c14b342 graphics: make address attribute for listen type='address' optional
We support omitting listen attribute of graphics element so we should
also support omitting address attribute of listen element.  This patch
also updates libvirt to always add a listen element into domain XML
except for VNC graphics if socket attribute is specified.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-05-17 10:41:45 +02:00
John Ferlan
e0d0e53086 conf: Add support for virtio-scsi iothreads
Add the ability to add an 'iothread' to the controller which will be how
virtio-scsi-pci and virtio-scsi-ccw iothreads have been implemented in qemu.

Describe the new functionality and add tests to parse/validate that the
new attribute can be added.
2016-05-04 09:59:14 -04:00
Boris Fiuczynski
383c6f7f4d tests: add tests for panic device model s390
Signed-off-by: Boris Fiuczynski <fiuczy@linux.vnet.ibm.com>
2016-05-02 17:01:40 +02:00
Boris Fiuczynski
73e4e10e62 qemu: add default panic device to S390 guests
This patch adds by default a panic device with model s390 to S390 guests.

Signed-off-by: Boris Fiuczynski <fiuczy@linux.vnet.ibm.com>
2016-05-02 17:01:40 +02:00
Martin Kletzander
55320c23dd qemu: Regenerate VNC socket paths
Similarly to what commit 7140807917 did with some internal paths,
clear vnc socket paths that were generated by us.  Having such path in
the definition can cause trouble when restoring the domain.  The path is
generated to the per-domain directory that contains the domain ID.
However, that ID will be different upon restoration, so qemu won't be
able to create that socket because the directory will not be prepared.

To be able to migrate to older libvirt, skip formatting the socket path
in migratable XML if it was autogenerated.  And mark it as autogenerated
if it already exists and we're parsing live XML.

Best viewed with '-C'.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1326270

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
2016-04-28 16:13:45 +02:00
Cole Robinson
67f2b72723 conf: Drop restrictions on rng backend path
Currently we only allow /dev/random and /dev/hwrng as host input
for <rng><backend model='random'/> device. This was added after
various upstream discussions in commit 4932ef45

However this restriction has generated quite a few complaints over
the years, so a new discussion was initiated:

http://www.redhat.com/archives/libvir-list/2016-April/msg00987.html

Several people suggested removing the restriction, and nobody really
spoke up to defend it. So this patch drops the path restriction
entirely

https://bugzilla.redhat.com/show_bug.cgi?id=1074464
2016-04-26 11:43:33 -04:00
Cole Robinson
600a666ce5 schema: Allow space character in disk vendor/product
The hex range already tried to allow for it, but it wasn't using
the correct XML hex syntax. Fix it, and test it
2016-04-26 10:29:44 -04:00
John Ferlan
dd1400280e tests: Fix syntax in iSCSI auth/secret tests
While working on the tests for the secret initialization vector, I found
that the existing iSCSI tests were lacking in how they defined the IQN.
Many had IQN's of just 'iqn.1992-01.com.example' for one disk while using
'iqn.1992-01.com.example/1' for the second disk (same for hostdevs - guess
how they were copied/generated).

Typically (and documented this way), IQN's would include be of the form
'iqn.1992-01.com.example:storage/1' indicating an IQN using "storage" for
naming authority specific string and "/1" for the iSCSI LUN.

So modify the input XML's to use the more proper format - this of course
has a ripple effect on the output XML and the args.

Also note that the "%3A" is generated by the virURIFormat/xmlSaveUri
to represent the colon.

Signed-off-by: John Ferlan <jferlan@redhat.com>
2016-04-18 12:31:50 -04:00
Laine Stump
bc07251f59 conf: new pci controller model pcie-expander-bus
This controller provides a single PCIe port on a new root. It is
similar to pci-expander-bus, intended to provide a bus that can be
associated with a guest-identifiable NUMA node, but is for
machinetypes with PCIe rather than PCI (e.g. q35-based machinetypes).

Aside from PCIe vs. PCI, the other main difference is that a
pci-expander-bus has a companion pci-bridge that is automatically
attached along with it, but pcie-expander-bus has only a single port,
and that port will only connect to a pcie-root-port, or to a
pcie-switch-upstream-port. In order for the bus to be of any use in
the guest, it must have either a pcie-root-port or a
pcie-switch-upstream-port attached (and one or more
pcie-switch-downstream-ports attached to the
pcie-switch-upstream-port).
2016-04-14 14:00:34 -04:00
Laine Stump
400b297692 qemu: support new pci controller model "pci-expander-bus"
This is backed by the qemu device "pxb".

The pxb device always includes a pci-bridge that is at the bus number
of the pxb + 1.

busNr and <node> from the <target> subelement are used to set the
bus_nr and numa_node options for pxb.

During post-parse we validate that the domain's machinetype is
440fx-based (since the pxb device only works on 440fx-based machines),
and <node> also gets a sanity check to assure that the NUMA node
specified for the pxb (if any - it's optional) actually exists on the
guest.
2016-04-14 14:00:34 -04:00
Laine Stump
52f3d0a4d2 conf: new pci controller model pci-expander-bus
This is a standard PCI root bus (not a bridge) that can be added to a
440fx-based domain. Although it uses a PCI slot, this is *not* how it
is connected into the PCI bus hierarchy, but is only used for
control. Each pci-expander-bus provides 32 slots (0-31) that can
accept hotplug of standard PCI devices.

The usefulness of pci-expander-bus relative to a pci-bridge is that
the NUMA node of the bus can be specified with the <node> subelement
of <target>. This gives guest-side visibility to the NUMA node of
attached devices (presuming that management apps only assign a device
to a bus that has a NUMA node number matching the node number of the
device on the host).

Each pci-expander-bus also has a "busNr" attribute. The expander-bus
itself will take the busNr specified, and all buses that are connected
to this bus (including the pci-bridge that is automatically added to
any expander bus of model "pxb" (see the next commit)) will use
busNr+1, busNr+2, etc, and the pci-root (or the expander-bus with next
lower busNr) will use bus numbers lower than busNr.
2016-04-14 14:00:34 -04:00
Laine Stump
0d668434f4 conf: allow use of slot 0 in a dmi-to-pci-bridge
When support for dmi-to-pci-bridge was added, it was assumed that,
just as with the pci-root bus, slot 0 was reserved. This is not the
case - it can be used to connect a device just like any other slot, so
remove the restriction and update the test cases that auto-assign an
address on a dmi-to-pci-bridge.
2016-04-14 14:00:33 -04:00
Pavel Hrdina
1d9d0c9397 domain_conf: fix graphics parsing
Commit dc98a5bc refactored the code a lot and forget about checking if
listen attribute is specified.  This ensures that listen attribute and
first listen element are compared only if both exist.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-04-11 13:50:55 +02:00
Maxim Nestratov
7068b56c85 conf: qemu: Add support for more HyperV Enlightenment features
This patch adds support for "vpindex", "runtime", "synic",
"stimer", and "vendor_id" features available in qemu 2.5+.

- When Hyper-V "vpindex" is on, guest can use MSR HV_X64_MSR_VP_INDEX
to get virtual processor ID.

- Hyper-V "runtime" enlightement feature allows to use MSR
HV_X64_MSR_VP_RUNTIME to get the time the virtual processor consumes
running guest code, as well as the time the hypervisor spends running
code on behalf of that guest.

- Hyper-V "synic" stands for Synthetic Interrupt Controller, which is
lapic extension controlled via MSRs.

- Hyper-V "stimer" switches on Hyper-V SynIC timers MSR's support.
Guest can setup and use fired by host events (SynIC interrupt and
appropriate timer expiration message) as guest clock events

- Hyper-V "reset" allows guest to reset VM.

- Hyper-V "vendor_id" exposes hypervisor vendor id to guest.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Signed-off-by: John Ferlan <jferlan@redhat.com>
2016-03-28 13:10:18 -04:00
Alexander Burluka
946758deee Add global_period and global_quota XML validation test
Signed-off-by: Alexander Burluka <aburluka@virtuozzo.com>
2016-03-01 14:29:06 +00:00
Pavel Hrdina
119cd06ef7 domain_conf: always set primary video device as primary
We always place primary video device at first place, to make it easier
to create a qemu command or format an xml, but we should also set the
primary boolean for primary video device to 'true'.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-03-01 14:17:09 +01:00
Marc-André Lureau
937ebba00e qemu: add spice opengl support
Add Spice graphics gl attribute. qemu 2.6 should have -spice gl=on argument to
enable opengl rendering context (patches on the ML). This is necessary to
actually enable virgl rendering.

Add a qemuxml2argv test for virtio-gpu + spice with virgl.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2016-03-01 09:45:47 +01:00
Paolo Bonzini
fc922eb208 qemu: add support for LSI SAS1068 (aka MPT Fusion) SCSI controller
This does nothing more than adding the new device and capability.
The device is present since QEMU 2.6.0.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2016-02-22 10:10:52 +00:00
Andrea Bolognani
998a936c4c tests: Add more GIC test cases
Test all kinds of scenarios, including guests asking for GIC but
failing to specify a version, guests specifying an invalid version
and guests trying to use GIC with non-virt or even non-ARM machines.
2016-02-16 15:42:20 +01:00
Andrea Bolognani
161a341850 tests: Reorganize and simplify GIC test cases
Unify the naming to prepare for new test cases that will be added
later on.

Convert a couple of output XML files for the qemuxml2xml test to
symlinks while at it, since they were identical to the corresponding
input XML files anyways.

Moreover, since we're only interested in testing GIC support here,
simplify XML files by getting rid of the unrelevant bits.
2016-02-16 15:39:57 +01:00
Andrea Bolognani
bd23695055 qemu: Always enable GIC on ARM virt machines
GIC is always available to ARM virt machines, and the domain XML should
reflect this fact.
2016-02-16 14:58:58 +01:00
Cole Robinson
5a1ccaeb00 tests: qemu: More aarch64 virtio and pci tests
Clarify the point of some of the test cases by renaming them. Add more
xml2xml tests.
2016-02-09 16:09:01 -05:00
Cole Robinson
c1c4d0d5a5 tests: qemuxml2xml: assign device addresses
We use the PreFormat callback for this. Many test cases need to be extended
to pass in proper qemuCaps flags so AssignAddresses doesn't throw errors.

One test case (pcie-root-port-too-many) is dropped, since it was meant
only for checking an error condition in qemuxml2argv, and one we add in
AssignAddresses it errors here too.

Long term I think AssignAddresses should be handled in qemu's PostParse
callback, but that's not entirely straightforward. Handling it here
means we can get the test suite churn over with.
2016-02-09 16:09:01 -05:00
Cole Robinson
e9394d699c tests: qemuxml2argv: remove some QEMU_CAPS_DEVICE problem cases
When we unconditionally enable QEMU_CAPS_DEVICE, these tests need
some massaging, so do it ahead of time to not mix it in with the
big test refresh.

- minimal-s390 is not a real world working config, so drop it
- disk-usb was testing for an old code path that will be removed.
  instead use it to test lack of USB disk support, and rename it
  to disk-usb-nosupport. Switch xml2xml to use disk-usb-device for
  input.
- cputune-numatune was needlessly using q35, switch it to an older
  machine type
2016-02-09 13:42:23 -05:00
Cole Robinson
d093d623e3 tests: qemuxml2xml: Always use different output file
Most qemuxml2xml tests expect that the input XML is unchanged after
parsing. This is unlike 99% of new qemu configs in the wild, which after
initial parsing end up with stable PCI device addresses. The xml2xml bit
doesn't currently hit that code path though, so most XML testing indeed
does not change.

Future patches will add that PCI address bits, which means most test cases
will have different output. So let's do away with the hardcoded same vs
different test split, and always track a separate output file. Tests can
still have same input and output, it just necessitates 2 separate XML files.
2016-02-09 10:22:05 -05:00
Peter Krempa
6dfb4507f5 conf: Fix how iothread scheduler info is stored
Similarly to previous commit change the way how iothread scheduler info
is stored and clean up a lot of unnecessary code.
2016-02-08 09:51:34 +01:00
Pavel Hrdina
36785c7e77 device: cleanup input device code
The current code was a little bit odd.  At first we've removed all
possible implicit input devices from domain definition to add them later
back if there was any graphics device defined while parsing XML
description.  That's not all, while formating domain definition to XML
description we at first ignore any input devices with bus different to
USB and VIRTIO and few lines later we add implicit input devices to XML.

This seems to me as a lot of code for nothing.  This patch may look
to be more complicated than original approach, but this is a preferred
way to modify/add driver specific stuff only in those drivers and not
deal with them in common parsing/formating functions.

The update is to add those implicit input devices into config XML to
follow the real HW configuration visible by guest OS.

There was also inconsistence between our behavior and QEMU's in the way,
that in QEMU there is no way how to disable those implicit input devices
for x86 architecture and they are available always, even without graphics
device.  This applies also to XEN hypervisor.  VZ driver already does its
part by putting correct implicit devices into live XML.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2016-01-26 17:53:33 +01:00
Peter Krempa
f82a8014c0 tests: qemuxml2xml: Order pinning information numerically
A future patch will refactor the storage of the pinning information in a
way where the ordering will be lost. Order them numerically to avoid
changing the tests later.
2016-01-25 17:53:07 +01:00
Laine Stump
163338ec28 qemu: prefer 00:1D.x and 00:1A.x for USB2 controllers on Q35
The real Q35 machine puts the first USB controller set (EHCI+(UHCIx4))
on bus 0 slot 0x1D, and the 2nd USB controller set on bus 0 slot 0x1A,
so let's attempt to make the virtual machine match that for
controllers with auto-assigned addresses when possible.

Three test cases were added to assure that the proper addresses are
assigned - one with a single set of unaddressed USB controllers, one
with 3 (to grab both preferred slots plus one more), and one with the
order of the controller definitions reordered, to assure that the
auto-assignment isn't mixed up by order.
2016-01-11 13:04:17 -05:00
Dmitry Andreev
ca6ddffe2c qemu: add support for hv_crash feature as a panic device
Panic device type used depends on 'model' attribute.

If no model is specified then device type depends on hypervisor
and guest arch. 'pseries' model is used for pSeries guest and
'isa' model is used in other cases.

XML:
<devices>
  <panic model='hyperv'/>
</devices>

QEMU command line:
qemu -cpu <cpu_model>,hv_crash
2015-11-25 14:46:20 +01:00
Pavel Hrdina
fc03eb53c0 domain-conf: reorder usb controllers so the master is first
USB controllers can share the same 'index' which indicates, that there
is some sort of master-companion relationship.  Reorder the controllers
in XML in to place the master controller before its companions.  This is
required by QEMU to not fail with error message:

error: internal error: process exited while connecting to monitor:
2015-10-26T16:25:17.630265Z qemu-system-x86_64:
-device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x6:
USB bus 'usb.0' not found

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1166452

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
2015-11-11 15:30:49 +01:00
Luyao Huang
83ae3ee39b conf: fix crash when parsing a unordered NUMA <cell/>
https://bugzilla.redhat.com/show_bug.cgi?id=1260846

Introduced by 8fedbbdb, if we parse an unordered NUMA cell, will
get a segfault. This is because of a check for overlapping @cpus
sets we have there. However, since the array to hold guest NUMA
cells is allocated upfront and therefore it contains all zeros,
an out of order cell will break our assumption that cell IDs have
increasing character. At this point we try to access yet NULL
bitmap and therefore segfault.

Signed-off-by: Luyao Huang <lhuang@redhat.com>
2015-09-08 10:40:20 +02:00
Laine Stump
8dc88aeed6 conf: add new <target> subelement with chassisNr attribute to <controller>
There are some configuration options to some types of pci controllers
that are currently automatically derived from other parts of the
controller's configuration. For example, in qemu a pci-bridge
controller has an option that is called "chassis_nr"; up until now
libvirt has always set chassis_nr to the index of the pci-bridge. So
this:

  <controller type='pci' model='pci-bridge' index='2'/>

will always result in:

  -device pci-bridge,chassis_nr=2,...

on the qemu commandline. In the future we may decide there is a better
way to derive that option, but even in that case we will need for
existing domains to retain the same chassis_nr they were using in the
past - that is something that is visible to the guest so it is part of
the guest ABI and changing it would lead to problems for migrating
guests (or just guests with very picky OSes).

The <target> subelement has been added as a place to put the new
"chassisNr" attribute that will be filled in by libvirt when it
auto-generates the chassisNr; it will be saved in the config, then
reused any time the domain is started:

  <controller type='pci' model='pci-bridge' index='2'>
    <model type='pci-bridge'/>
    <target chassisNr='2'/>
  </controller>

The one oddity of all this is that if the controller configuration
is changed (for example to change the index or the pci address
where the controller is plugged in), the items in <target> will
*not* be re-generated, which might lead to conflict. I can't
really see any way around this, but fortunately if there is a
material conflict qemu will let us know and we will pass that on
to the user.
2015-08-09 21:35:00 -04:00