qapi.py has a hardcoded white-list of command names that may violate
the rules on permitted return types.  Add a new pragma directive
'returns-whitelist', and use it to replace the hard-coded white-list.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1489582656-31133-6-git-send-email-armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Section "Commands" qualifies its rules on permitted argument and
return types "with one exception noted below when 'gen' is used".  The
note went away in commit 2d21291a.  Clean up the dangling references.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1489582656-31133-5-git-send-email-armbru@redhat.com>

This reverts commit 3313b612's changes to tests/qapi-schema/, except
for tests/qapi-schema/doc-*.

We could keep some of these doc comments to serve as positive test
cases.  However, they don't actually add to what we get from doc
comment use in actual schemas, as we we don't test output matches
expectations, and don't systematically cover doc comment features.
Proper positive test coverage would be nice.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Message-Id: <1489582656-31133-4-git-send-email-armbru@redhat.com>

Since we added the documentation generator in commit 3313b612, doc
comments are mandatory.  That's a very good idea for a schema that
needs to be documented, but has proven to be annoying for testing.

Make doc comments optional again, but add a new directive

    { 'pragma': { 'doc-required': true } }

to let a QAPI schema require them.

Add test cases for the new pragma directive.  While there, plug a
minor hole in includ directive test coverage.

Require documentation in the schemas we actually want documented:
qapi-schema.json and qga/qapi-schema.json.

We could probably make qapi2texi.py cope with incomplete
documentation, but for now, simply make it refuse to run unless the
schema has 'doc-required': true.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1489582656-31133-3-git-send-email-armbru@redhat.com>
[qapi-code-gen.txt wording tweaked]
Reviewed-by: NEric Blake <eblake@redhat.com>

Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1489582656-31133-2-git-send-email-armbru@redhat.com>

The qmp-shell property parser currently rejects attempts to
set string properties to the empty string eg

  (QEMU) migrate-set-parameters  tls-hostname=
  Error while parsing command line: Expected a key=value pair, got 'tls-hostname='
command format: <command-name>  [arg-name1=arg1] ... [arg-nameN=argN]

This is caused by checking the wrong condition after splitting
the parameter on '='. The "partition" method will return "" for
the separator field, if the seperator was not present, so that
is the correct thing to check for malformed syntax.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Message-Id: <20170302122429.7737-1-berrange@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

STRUCT_FMT is generic enough, rename it to TYPE_FMT, use it for unions.

Rename COMMAND_FMT to MSG_FMT, since it applies to both commands and
events.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170125130308.16104-2-marcandre.lureau@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

virtio, pc: fixes

Some fixes to fallback from using virtio caching,
pls a minor vm gen id fix.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Wed 15 Mar 2017 17:59:25 GMT
# gpg:                using RSA key 0x281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17  0970 C350 3912 AFBE 8E67
#      Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA  8A0D 281F 0DB8 D28D 5469

* remotes/mst/tags/for_upstream:
  virtio-pci: reset modern vq meta data
  Revert "virtio: unbreak virtio-pci with IOMMU after caching ring translations"
  pci: introduce a bus master container
  virtio: validate address space cache during init
  virtio: destroy region cache during reset
  virtio: guard against NULL pfn
  Bugfix: Handle error if VM Generation ID device not present
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

We don't reset proxy->vqs[].{num|desc[]|avail[]|used[]}. This means if
a driver enable the vq without setting vq address after reset. The old
addresses were leaked. Fixing this by resetting modern vq meta data
during device reset.

Cc: qemu-stable@nongnu.org
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

This reverts commit
96a8821d. Previous patch is a better
solution which does not require a strict order between virtio and IOMMU.

CC: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>

Miscellaneous patches for 2017-03-15

# gpg: Signature made Wed 15 Mar 2017 13:12:35 GMT
# gpg:                using RSA key 0x3870B400EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-misc-2017-03-15:
  coverity-model: model address_space_read/write
  tests: Use error_free_or_abort() where appropriate
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

96a8821d ("virtio: unbreak virtio-pci with IOMMU after caching ring
translations") tries to make IOMMU works with virtio memory region
cache, but it requires IOMMU to be created before any virtio
devices. This is sub optimal, fixing this by introduce a bus master
container to make sure address space can be initialized during device
registering, and then we can safely set alias and make
bus_master_enable_region as its subregion during bus master
initialization.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

We don't check the return value of address_space_cache_init(), this
may lead buggy driver use incorrect region caches. Instead of
triggering an assert, catch and warn this early in
virtio_init_region_cache().

Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

We don't destroy region cache during reset which can make the maps
of previous driver leaked to a buggy or malicious driver that don't
set vring address before starting to use the device. Fix this by
destroy the region cache during reset and validate it before trying to
see them.

Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

To avoid access stale memory region cache after reset, this patch
check the existence of virtqueue pfn for all exported virtqueue access
helpers before trying to use them.

Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

This was crashing due to NULL-pointer dereference

QMP Test case:
==============

(QEMU) query-vm-generation-id
{"error": {"class": "GenericError", "desc": "VM Generation ID device not
found"}}

HMP Test case:
==============
virsh # qemu-monitor-command --hmp 3 info vm-generation-id
VM Generation ID device not found
Signed-off-by: NBen Warren <ben@skyportsystems.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

# gpg: Signature made Wed 15 Mar 2017 05:05:04 GMT
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  os: don't corrupt pre-existing memory-backend data with prealloc
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Fix global property and -cpu handling bug

This bug fix was supposed to be applied just after 2.8.0 was
released, but it slipped through the cracks. Sending it now for
the next -rc.

# gpg: Signature made Tue 14 Mar 2017 20:04:50 GMT
# gpg:                using RSA key 0x2807936F984DC5A6
# gpg: Good signature from "Eduardo Habkost <ehabkost@redhat.com>"
# Primary key fingerprint: 5A32 2FD5 ABC4 D3DB ACCF  D1AA 2807 936F 984D C5A6

* remotes/ehabkost/tags/machine-pull-request:
  machine: Convert abstract typename on compat_props to subclass names
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Commit eb7eeb88 ("memory: split address_space_read and
address_space_write", 2015-12-17) made address_space_rw
dispatch to one of address_space_read or address_space_write,
rather than vice versa.

For callers of address_space_read and address_space_write this
causes false positive defects when Coverity sees a length-8 write in
address_space_read and a length-4 (e.g. int*) buffer to read into.
As long as the size of the buffer is okay, this is a false positive.

Reflect the code change into the model.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170315081641.20588-1-pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Done with this Coccinelle semantic patch:

    @@
    expression E;
    @@
    -    g_assert(E);
    -    error_free(E);
    +    error_free_or_abort(&E);
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1487362554-5688-1-git-send-email-armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

When using a memory-backend object with prealloc turned on, QEMU
will memset() the first byte in every memory page to zero. While
this might have been acceptable for memory backends associated
with RAM, this corrupts application data for NVDIMMs.

Instead of setting every page to zero, read the current byte
value and then just write that same value back, so we are not
corrupting the original data. Directly write the value instead
of memset()ing it, since there's no benefit to memset for a
single byte write.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NAndrea Arcangeli <aarcange@redhat.com>
Message-id: 20170303113255.28262-1-berrange@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Original problem description by Greg Kurz:

> Since commit "9a4c0e22 hw/virtio-pci: fix virtio
> behaviour", passing -device virtio-blk-pci.disable-modern=off
> has no effect on 2.6 machine types because the internal
> virtio-pci.disable-modern=on compat property always prevail.

The same bug also affects other abstract type names mentioned on
compat_props by machine-types: apic-common, i386-cpu, pci-device,
powerpc64-cpu, s390-skeys, spapr-pci-host-bridge, usb-device,
virtio-pci, x86_64-cpu.

The right fix for this problem is to make sure compat_props and
-global options are always applied in the order they are
registered, instead of reordering them based on the type
hierarchy. But changing the ordering rules of -global is risky
and might break existing configurations, so we shouldn't do that
on a stable branch.

This is a temporary hack that will work around the bug when
registering compat_props properties: if we find an abstract class
on compat_props, register properties for all its non-abstract
subtypes instead. This will make sure -global won't be overridden
by compat_props, while keeping the existing ordering rules on
-global options.

Note that there's one case that won't be fixed by this hack:
"-global spapr-pci-vfio-host-bridge.<option>=<value>" won't be
able to override compat_props, because spapr-pci-host-bridge is
not an abstract class.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Message-Id: <1481575745-26120-1-git-send-email-ehabkost@redhat.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NHalil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Tested-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

* "x" monitor command fix for KVM (Christian)
* MemoryRegion name documentation (David)
* mem-prealloc optimization (Jitendra)
* -icount/MTTCG fixes (me)
* "info mtree" niceness (Peter)
* NBD drop_sync buffer overflow (Vladimir/Eric)
* small cleanups and bugfixes (Li, Lin, Suramya, Thomas)
* fix for "-device kvmclock" w/TCG (Eduardo)
* debug output before crashing on KVM_{GET,SET}_MSRS (Eduardo)

# gpg: Signature made Tue 14 Mar 2017 13:42:05 GMT
# gpg:                using RSA key 0xBFFBD25F78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>"
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* remotes/bonzini/tags/for-upstream:
  nbd/client: fix drop_sync [CVE-2017-2630]
  memory: info mtree check mr range overflow
  icount: process QEMU_CLOCK_VIRTUAL timers in vCPU thread
  main-loop: remove now unnecessary optimization
  cpus: define QEMUTimerListNotifyCB for QEMU system emulation
  qemu-timer: do not include sysemu/cpus.h from util/qemu-timer.h
  qemu-timer: fix off-by-one
  target/nios2: take BQL around interrupt check
  scsi: mptsas: fix the wrong reading size in fetch request
  util: Removed unneeded header from path.c
  configure: add the missing help output for optional features
  scripts/dump-guest-memory.py: fix int128_get64 on recent gcc
  kvmclock: Don't crash QEMU if KVM is disabled
  kvm: Print MSR information if KVM_{GET,SET}_MSRS failed
  exec: add cpu_synchronize_state to cpu_memory_rw_debug
  mem-prealloc: reduce large guest start-up and migration time.
  docs: Add a note about mixing bootindex with "-boot order"
  memory_region: Fix name comments
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Commit 4881658a introduced a call to arm_get_cpu_by_id(),
and Coverity noticed that we weren't checking that it didn't
return NULL (CID 1371652).

Normally this won't happen (because all 4 CPUs are expected
to exist), but it's possible the user requested fewer CPUs
on the command line. Handle this possibility by silently
doing nothing, which is the same behaviour as before commit
4881658a and also how we handle the other CPU operations
(since we ignore the INVALID_PARAM returns from arm_set_cpu_on()
and friends).

There is a slight behavioural difference to the pre-4881658a
situation: the "reset this core" bit will remain set rather
than not being permitted to be set. The imx6 datasheet is
unclear about the behaviour in this odd corner case, so we
opt for the simpler code rather than complicated logic to
maintain identical behaviour.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1488542374-1256-1-git-send-email-peter.maydell@linaro.org
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>

Add the ability for the user to use .toast files with QEMU. This format works
just like ISO files.
Signed-off-by: NJohn Arbuckle <programmingkidx@gmail.com>
Message-id: 0C9DA454-E3DC-4291-806E-9A96557DE833@gmail.com
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target-arm queue:
 * arm-powerctl: Fix psci info return values
 * implement armv8 PMUSERENR (user-mode enable bits)

# gpg: Signature made Tue 14 Mar 2017 11:31:11 GMT
# gpg:                using RSA key 0x3C2525ED14360CDE
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>"
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>"
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>"
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-target-arm-20170314:
  target/arm/arm-powerctl: Fix psci info return values
  target/arm: implement armv8 PMUSERENR (user-mode enable bits)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Comparison symbol is misused. It may lead to memory corruption.
Introduced in commit 7d3123e1.
Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20170203154757.36140-6-vsementsov@virtuozzo.com>
[eblake: add CVE details, update conditional]
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170307151627.27212-1-eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The address of memory regions might overflow when something wrong
happened, like reported in:

https://lists.gnu.org/archive/html/qemu-devel/2017-03/msg02043.html

For easier debugging, let's try to detect it.
Reported-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Message-Id: <1489496187-624-1-git-send-email-peterx@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

icount has become much slower after tcg_cpu_exec has stopped
using the BQL.  There is also a latent bug that is masked by
the slowness.

The slowness happens because every occurrence of a QEMU_CLOCK_VIRTUAL
timer now has to wake up the I/O thread and wait for it.  The rendez-vous
is mediated by the BQL QemuMutex:

- handle_icount_deadline wakes up the I/O thread with BQL taken
- the I/O thread wakes up and waits on the BQL
- the VCPU thread releases the BQL a little later
- the I/O thread raises an interrupt, which calls qemu_cpu_kick
- the VCPU thread notices the interrupt, takes the BQL to
  process it and waits on it

All this back and forth is extremely expensive, causing a 6 to 8-fold
slowdown when icount is turned on.

One may think that the issue is that the VCPU thread is too dependent
on the BQL, but then the latent bug comes in.  I first tried removing
the BQL completely from the x86 cpu_exec, only to see everything break.
The only way to fix it (and make everything slow again) was to add a dummy
BQL lock/unlock pair.

This is because in -icount mode you really have to process the events
before the CPU restarts executing the next instruction.  Therefore, this
series moves the processing of QEMU_CLOCK_VIRTUAL timers straight in
the vCPU thread when running in icount mode.

The required changes include:

- make the timer notification callback wake up TCG's single vCPU thread
  when run from another thread.  By using async_run_on_cpu, the callback
  can override all_cpu_threads_idle() when the CPU is halted.

- move handle_icount_deadline after qemu_tcg_wait_io_event, so that
  the timer notification callback is invoked after the dummy work item
  wakes up the vCPU thread

- make handle_icount_deadline run the timers instead of just waking the
  I/O thread.

- stop processing the timers in the main loop
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This optimization is not necessary anymore, because the vCPU now drops
the I/O thread lock even with TCG.  Drop it to simplify the code and
avoid the "I/O thread spun for 1000 iterations" warning.
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

There is no change for now, because the callback just invokes
qemu_notify_event.
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This dependency is the wrong way, and we will need util/qemu-timer.h from
sysemu/cpus.h in the next patch.
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

If the first timer is exactly at the current value of the clock, the
deadline is met and the timer should fire.  This fixes itself on the next
iteration of the loop without icount; with icount, however, execution
of instructions will stop exactly at the deadline and won't proceed.
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The interrupt controller does not have its own locking.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When fetching request, it should read sizeof(*hdr), not the
pointer hdr.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Message-Id: <1489488980-130668-1-git-send-email-liqiang6-s@360.cn>
Cc: qemu-stable@nongnu.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NSuramya Shah <shah.suramya@gmail.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Message-Id: <20170310163948.7567-1-shah.suramya@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NLin Ma <lma@suse.com>
Message-Id: <20170310101405.26974-1-lma@suse.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The Int128 is no longer a struct, reaching a python exception:
Python Exception <class 'gdb.error'> Attempt to extract a component of a value that is not a (null).:

Replace struct access with a cast to uint64[] instead.

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=1427466Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20170310112819.16760-1-marcandre.lureau@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Most machines don't allow sysbus devices like "kvmclock" to be
created from the command-line, but some of them do (the ones with
has_dynamic_sysbus=true). In those cases, it's possible to
manually create a kvmclock device without KVM being enabled,
making QEMU crash:

  $ qemu-system-x86_64 -machine q35,accel=tcg -device kvmclock
  Segmentation fault (core dumped)

This changes kvmclock's realize method to return an error if KVM
is disabled, to ensure it won't crash QEMU.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20170309185046.17555-1-ehabkost@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>