Commit 8cc4678 ("megasas: remove useless check for cmd->frame", 2016-07-17) was
wrong because I trusted Coverity too much. It turns out that there _is_ a
path through which cmd->frame can become NULL. After megasas_handle_frame's
switch (md->frame->header.frame_cmd), megasas_init_firmware can be called.
From there, megasas_reset_frames will call megasas_unmap_frame which resets
cmd->frame = NULL.
However, there is another bug to fix in there, because megasas_unmap_frame
is called again after setting the command status. In this case QEMU should
not do anything, instead it calls pci_dma_unmap again. Harmless, but
better fix it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
While customary, the /chosen and /memory devicetree nodes do not have to
exist. Create if necessary. Also create the /memory/device_type property
if needed.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 1479346221-18474-1-git-send-email-linux@roeck-us.net
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This patch fixes the generic-loader file loading to only set the program
counter if a CPU is specified. This follows what is written in the
documentation and was always part of the original intention.
Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 537bf4d08be7acf7a89b590cff69e19db7f0a6cd.1478908712.git.alistair.francis@xilinx.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Make it clear that having Linux is a hard requirement for this
feature.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The cache-clean-interval option of qcow2 only works on Linux. However
we allow setting it in other systems regardless of whether it works or
not.
In those systems this option is not simply a no-op: it actually
invalidates perfectly valid cache tables for no good reason without
freeing their memory.
This patch forbids using that option in non-Linux systems.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We are using QEMU_MADV_DONTNEED to discard the memory of individual L2
cache tables. The problem with this is that those semantics are
specific to the Linux madvise() system call. Other implementations of
madvise() (including the very Linux implementation of posix_madvise())
don't do that, so we cannot use them for the same purpose.
This patch makes the code Linux-specific and uses madvise() directly
since there's no point in going through qemu_madvise() for this.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
"The multiplier and multiplicand are both word operands, and the result
is a long-word operand."
So compute flags on a long-word result, not on a word result.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
backends.
-----BEGIN PGP SIGNATURE-----
iEYEABECAAYFAlg1kVUACgkQAvw66wEB28IIzACfXKtN7ut2ZiakDKHH182CadeO
PoMAni7ivvO1KGqO9osvwiEeY2KPIkED
=ZAcB
-----END PGP SIGNATURE-----
Merge remote-tracking branch 'gkurz/tags/for-upstream' into staging
This pull request fixes some leaks (memory, fd) in the handle and proxy
backends.
# gpg: Signature made Wed 23 Nov 2016 12:53:41 PM GMT
# gpg: using DSA key 0x02FC3AEB0101DBC2
# gpg: Good signature from "Greg Kurz <groug@kaod.org>"
# gpg: aka "Greg Kurz <groug@free.fr>"
# gpg: aka "Greg Kurz <gkurz@fr.ibm.com>"
# gpg: aka "Greg Kurz <gkurz@linux.vnet.ibm.com>"
# gpg: aka "Gregory Kurz (Groug) <groug@free.fr>"
# gpg: aka "Gregory Kurz (Cimai Technology) <gkurz@cimai.com>"
# gpg: aka "Gregory Kurz (Meiosys Technology) <gkurz@meiosys.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg: There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 2BD4 3B44 535E C0A7 9894 DBA2 02FC 3AEB 0101 DBC2
* gkurz/tags/for-upstream:
9pfs: add cleanup operation for proxy backend driver
9pfs: add cleanup operation for handle backend driver
9pfs: add cleanup operation in FileOperations
9pfs: adjust the order of resource cleanup in device unrealize
Message-id: 1479920298-24983-1-git-send-email-groug@kaod.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
"The size of the operation can be specified as word or long.
Word length source operands are sign-extended to 32 bits for
comparison."
So comparison is always done using OS_LONG.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
opcodes of "EXG Ax,Ay" and "EXG Dx,Dy" have been swapped
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <rth@twiddle.net>
The guest sends discard requests as u64 sector/count pairs, but the
block layer operates internally with s64/s32 pairs. The conversion
leads to IO errors in the guest, the discard request is not processed.
domU.cfg:
'vdev=xvda, format=qcow2, backendtype=qdisk, target=/x.qcow2'
domU:
mkfs.ext4 -F /dev/xvda
Discarding device blocks: failed - Input/output error
Fix this by splitting the request into chunks of BDRV_REQUEST_MAX_SECTORS.
Add input range checking to avoid overflow.
Fixes f313520 ("xen_disk: add discard support")
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
In the init operation of proxy backend dirver, it allocates a
V9fsProxy struct and some other resources. We should free these
resources when the 9pfs device is unrealized. This is what this
patch does.
Signed-off-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
In the init operation of handle backend dirver, it allocates a
handle_data struct and opens a mount file. We should free these
resources when the 9pfs device is unrealized. This is what this
patch does.
Signed-off-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
Currently, the backend of VirtFS doesn't have a cleanup
function. This will lead resource leak issues if the backed
driver allocates resources. This patch addresses this issue.
Signed-off-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
Unrealize should undo things that were set during realize in
reverse order. So should do in the error path in realize.
Signed-off-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
Here's the first set of 2.8 hard freeze bugfixes for ppc.
The biggest thing here is a batch of fixes for migration breakages in
both 2.7 and current 2.8. Alas, there is at least one more migration
problem, which prevents memory unplug after a migration. I hoped to
include a fix for that here, but it turned out to have some problems
bigger than those it was solving. So, I expect at least one more hard
freeze pull request.
There are also a few other assorted bug fixes.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=cds8
-----END PGP SIGNATURE-----
Merge remote-tracking branch 'dgibson/tags/ppc-for-2.8-20161123' into staging
ppc patch queue 2016-11-23
Here's the first set of 2.8 hard freeze bugfixes for ppc.
The biggest thing here is a batch of fixes for migration breakages in
both 2.7 and current 2.8. Alas, there is at least one more migration
problem, which prevents memory unplug after a migration. I hoped to
include a fix for that here, but it turned out to have some problems
bigger than those it was solving. So, I expect at least one more hard
freeze pull request.
There are also a few other assorted bug fixes.
# gpg: Signature made Wed 23 Nov 2016 02:25:42 AM GMT
# gpg: using RSA key 0x6C38CACA20D9B392
# gpg: Good signature from "David Gibson <david@gibson.dropbear.id.au>"
# gpg: aka "David Gibson (kernel.org) <dwg@kernel.org>"
# gpg: aka "David Gibson (Red Hat) <dgibson@redhat.com>"
# gpg: aka "David Gibson (ozlabs.org) <dgibson@ozlabs.org>"
# Primary key fingerprint: 75F4 6586 AE61 A66C C44E 87DC 6C38 CACA 20D9 B392
* dgibson/tags/ppc-for-2.8-20161123:
spapr: Fix 2.7<->2.8 migration of PCI host bridge
Revert "spapr: Fix migration of PCI host bridges from qemu-2.7"
target-ppc: Allow eventual removal of old migration mistakes
migration: Add VMSTATE_UINTTL_TEST()
target-ppc: Fix CPU migration from qemu-2.6 <-> later versions
ppc: Make uninorth interrupt swizzling identical to Grackle
target-ppc: fix index array of national digits
hw/char/spapr_vty: Return amount of free buffer entries in vty_can_receive()
ppc: BOOK3E: nothing should be done when MSR:PR is set
spapr: migration support for CAS-negotiated option vectors
tests/postcopy: Use KVM on ppc64 only if it is KVM-HV
Message-id: 1479869383-16162-1-git-send-email-david@gibson.dropbear.id.au
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
daa2369 "spapr_pci: Add a 64-bit MMIO window" subtly broke migration
from qemu-2.7 to the current version. It split the device's MMIO
window into two pieces for 32-bit and 64-bit MMIO.
The patch included backwards compatibility code to convert the old
property into the new format. However, the property value was also
transferred in the migration stream and compared with a (probably
unwise) VMSTATE_EQUAL. So, the "raw" value from 2.7 is compared to
the new style converted value from (pre-)2.8 giving a mismatch and
migration failure.
Along with the actual field that caused the breakage, there are
several other ill-advised VMSTATE_EQUAL()s. To fix forwards
migration, we read the values in the stream into scratch variables and
ignore them, instead of comparing for equality. To fix backwards
migration, we populate those scratch variables in pre_save() with
adjusted values to match the old behaviour.
To permit the eventual possibility of removing this cruft from the
stream, we only include these compatibility fields if a new
'pre-2.8-migration' property is set. We clear it on the pseries-2.8
machine type, which obviously can't be migrated backwards, but set it
on earlier machine type versions.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
This reverts commit 9b54ca0ba7.
The commit above corrected a migration breakage between qemu-2.7 and
qemu-2.8. However it did so by advancing the migration version for
the PCI host bridge, which obviously breaks migration backwards to
earlier qemu versions.
Although it's not totally essential, we'd like to maintain the
possibility for backwards migration, so revert the change in
preparation for a better fix.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Until very recently, the vmstate for ppc cpus included some poorly
thought out VMSTATE_EQUAL() components, that can easily break
migration compatibility, and did so between qemu-2.6 and later
versions. A hack was recently added which fixes this migration
breakage, but it leaves the unhelpful cruft of these fields in the
migration stream.
This patch adds a new cpu property allowing these fields to be removed
from the stream entirely. For the pseries-2.8 machine type - which
comes after the fix - and for all non-pseries machine types - which
aren't mature enough to care about cross-version migration - we remove
the fields from the stream.
For pseries-2.7 and earlier, The migration hack remains in place,
allowing backwards and forwards migration with the older machine
types.
This restricts the migration compatibility cruft to older machine
types, and at least opens the possibility of eventually deprecating
and removing it entirely.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
include/migration/cpu.h defines VMSTATE_UINTTL() and several variants
for migrating target_ulong fields. It's defined in terms of
VMSTATE_UINT32() or VMSTATE_UINT64() as appropriate.
It doesn't, however, include a VMSTATE_UINTTL_TEST() variant, which
I'm going to need shortly. So, add it.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
When migration for target-ppc was converted to vmstate, several
VMSTATE_EQUAL() checks were foolishly included of things that really
should be internal state. Specifically we verified equality of the
insns_flags and insns_flags2 fields, which are used within TCG to
determine which groups of instructions are available on this cpu
model. Between qemu-2.6 and qemu-2.7 we made some changes to these
classes which broke migration.
This path fixes migration both forwards and backwards. On migration
from 2.6 to later versions we import the fields into teporary
variables, which we then ignore. In migration backwards, we populate
the temporary fields from the runtime fields, but mask out the bits
which were added after qemu-2.6, allowing the VMSTATE_EQUAL in
qemu-2.6 to accept the stream.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
It's currently broken as it uses an incorrect shift, it tries
to use the slot number but uses the top bits of the bus number
instead.
Note: Neither implementation matches what OpenBIOS ends up putting
in the device-tree either, which will have to be fixed separately.
This is not quite correct for modelling a real Mac since Apple
tend to tie all 4 interrupt lines of a slot together and have
separate interrupts for every slot and every motherboard devices
going straight to the PIC but we'll sort that out later.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Fixes the big endian array access of national digits, from commits
b815587 and e2106d7.
Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The can_receive() callbacks of the character devices should return
the amount of characters that can be accepted at once, not just a
boolean value (which rather means only one character at a time).
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The server architecture (BOOK3S) specifies that any instruction that
sets MSR:PR will also set MSR:EE, IR and DR.
However there is no such behavior specification for the embedded
architecture (BOOK3E).
Signed-off-by: Vladimir Svoboda <ze.vlad@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Thomas Huth <thuth@redhat.com>
With the additional of the OV5_HP_EVT option vector, we now have
certain functionality (namely, memory unplug) that checks at run-time
for whether or not the guest negotiated the option via CAS. Because
we don't currently migrate these negotiated values, we are unable
to unplug memory from a guest after it's been migrated until after
the guest is rebooted and CAS-negotiation is repeated.
This patch fixes this by adding CAS-negotiated options to the
migration stream. We do this using a subsection, since the
negotiated value of OV5_HP_EVT is the only option currently needed
to maintain proper functionality for a running guest.
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The ppc64 postcopy test does not work with KVM-PR, and it is also
causing annoying warning messages when run on a x86 host. So let's
use KVM here only if we know that we're running with KVM-HV (which
automatically also means that we're running on a ppc64 host), and
fall back to TCG otherwise.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This fixes SCSI adapter self-tests done in MIPS Jazz emulation,
broken since ff589551c8.
Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Message-Id: <1479508397-8443-1-git-send-email-hpoussin@reactos.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit fa778fff wired up support to send the NBD_CMD_WRITE_ZEROES,
but forgot to inform the block layer that FUA unmapping of zeroes is
supported. Without BDRV_REQ_MAY_UNMAP listed as a supported flag,
the block layer will always insist on the NBD layer passing
NBD_CMD_FLAG_NO_HOLE, resulting in the server always allocating
things even when it was desired to let the server punch holes.
Similarly, failing to set BDRV_REQ_FUA means that the client may
send unnecessary NBD_CMD_FLUSH when it could have instead used the
NBD_CMD_FLAG_FUA bit.
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1479413642-22463-2-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In the user emulation code path, tlb_vaddr_to_host erronesously passed
vaddr as the guest address to be translated, instead of addr, the parameter
which actually contained the guest address.
This resulted in incorrect addresses being used when emulating block copy
(mvc/mvpg) and block clear (xc) instructions for the s390x target.
Signed-off-by: Bobby Bingham <koorogi@koorogi.info>
Message-Id: <20161113050523.23909-1-koorogi@koorogi.info>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Attach the usb bus of a new pvusb controller to the qdev associated
with the Xen backend. Any device connected to that controller can now
specify the bus and port directly via its properties.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Create a qdev plugged to the xen-sysbus for each new backend device.
This device can be used as a parent for all needed devices of that
backend. The id of the new device will be "xen-<type>-<dev>" with
<type> being the xen backend type (e.g. "qdisk") and <dev> the xen
backend number of the type under which it is to be found in xenstore.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
In order to have an easy way to add a new qdev with a specific id
carve out the needed functionality from qdev_device_add() into a new
function qdev_set_id().
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
Add a bus for Xen backend devices in order to be able to establish a
dedicated device path for pluggable devices.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
A typo prevents ISA interrupts from being recognized on cpu0,
which is where the smp kernel normally wants to see them.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Discard is advisory, so rounding the requests to alignment
boundaries is never semantically wrong from the data that
the guest sees. But at least the Dell Equallogic iSCSI SANs
has an interesting property that its advertised discard
alignment is 15M, yet documents that discarding a sequence
of 1M slices will eventually result in the 15M page being
marked as discarded, and it is possible to observe which
pages have been discarded.
Between commits 9f1963b and b8d0a980, we converted the block
layer to a byte-based interface that ultimately ignores any
unaligned head or tail based on the driver's advertised
discard granularity, which means that qemu 2.7 refuses to
pass any discard request smaller than 15M down to the Dell
Equallogic hardware. This is a slight regression in behavior
compared to earlier qemu, where a guest executing discards
in power-of-2 chunks used to be able to get every page
discarded, but is now left with various pages still allocated
because the guest requests did not align with the hardware's
15M pages.
Since the SCSI specification says nothing about a minimum
discard granularity, and only documents the preferred
alignment, it is best if the block layer gives the driver
every bit of information about discard requests, rather than
rounding it to alignment boundaries early.
Rework the block layer discard algorithm to mirror the write
zero algorithm: always peel off any unaligned head or tail
and manage that in isolation, then do the bulk of the request
on an aligned boundary. The fallback when the driver returns
-ENOTSUP for an unaligned request is to silently ignore that
portion of the discard request; but for devices that can pass
the partial request all the way down to hardware, this can
result in the hardware coalescing requests and discarding
aligned pages after all.
Reported by: Peter Lieven <pl@kamp.de>
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Right now, the block layer rounds discard requests, so that
individual drivers are able to assert that discard requests
will never be unaligned. But there are some ISCSI devices
that track and coalesce multiple unaligned requests, turning it
into an actual discard if the requests eventually cover an
entire page, which implies that it is better to always pass
discard requests as low down the stack as possible.
In isolation, this patch has no semantic effect, since the
block layer currently never passes an unaligned request through.
But the block layer already has code that silently ignores
drivers that return -ENOTSUP for a discard request that cannot
be honored (as well as drivers that return 0 even when nothing
was done). But the next patch will update the block layer to
fragment discard requests, so that clients are guaranteed that
they are either dealing with an unaligned head or tail, or an
aligned core, making it similar to the block layer semantics of
write zero fragmentation.
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Commit 443668ca rewrote the write_zeroes logic to guarantee that
an unaligned request never crosses a cluster boundary. But
in the rewrite, the new code assumed that at most one iteration
would be needed to get to an alignment boundary.
However, it is easy to trigger an assertion failure: the Linux
kernel limits loopback devices to advertise a max_transfer of
only 64k. Any operation that requires falling back to writes
rather than more efficient zeroing must obey max_transfer during
that fallback, which means an unaligned head may require multiple
iterations of the write fallbacks before reaching the aligned
boundaries, when layering a format with clusters larger than 64k
atop the protocol of file access to a loopback device.
Test case:
$ qemu-img create -f qcow2 -o cluster_size=1M file 10M
$ losetup /dev/loop2 /path/to/file
$ qemu-io -f qcow2 /dev/loop2
qemu-io> w 7m 1k
qemu-io> w -z 8003584 2093056
In fairness to Denis (as the original listed author of the culprit
commit), the faulty logic for at most one iteration is probably all
my fault in reworking his idea. But the solution is to restore what
was in place prior to that commit: when dealing with an unaligned
head or tail, iterate as many times as necessary while fragmenting
the operation at max_transfer boundaries.
Reported-by: Ed Swierk <eswierk@skyportsystems.com>
CC: qemu-stable@nongnu.org
CC: Denis V. Lunev <den@openvz.org>
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Paolo Bonzini
Guenter Roeck
Alistair Francis
Eduardo Habkost
Alberto Garcia
Stefan Hajnoczi
Mark Cave-Ayland
Laurent Vivier
Olaf Hering
Li Qiang
David Gibson
Benjamin Herrenschmidt
Jose Ricardo Ziviani
Thomas Huth
Vladimir Svoboda
Michael Roth
Hervé Poussineau
Eric Blake
Bobby Bingham
Juergen Gross
Jan Beulich
Richard Henderson