When running certain HMP commands ("info registers", "info cpustats",
"info tlb", "nmi", "memsave" or dumping virtual memory) with the "none"
machine, QEMU crashes with a segmentation fault. This happens because the
"none" machine does not have any CPUs by default, but these HMP commands
did not check for a valid CPU pointer yet. Add such checks now, so we get
an error message about the missing CPU instead.
Signed-off-by: NThomas Huth <thuth@redhat.com>
Message-Id: <1484309555-1935-1-git-send-email-thuth@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>

IOthreads were recently extended by new properties that can
enable/disable and configure aio polling.  This will also allow
other tools that uses QEMU to probe for existence of those new
properties via query-qmp-schema.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>
Message-Id: <3163c16d6ab4257f7be9ad44fe9cc0ce8c359e5a.1486718555.git.phrdina@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>

Commit 7a9877a0 made the 'device' parameter to BlockIOThrottle
optional, favoring 'id' instead.  But it forgot to update the
HMP usage to set has_device, which makes all attempts to change
throttling via HMP fail with "Need exactly one of 'device' and 'id'"

CC: qemu-stable@nongnu.org
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <20170120230359.4244-1-eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>

# gpg: Signature made Tue 21 Feb 2017 15:40:05 GMT
# gpg:                using RSA key 0xBDBE7B27C0DE3057
# gpg: Good signature from "Jeffrey Cody <jcody@redhat.com>"
# gpg:                 aka "Jeffrey Cody <jeff@codyprime.org>"
# gpg:                 aka "Jeffrey Cody <codyprime@gmail.com>"
# Primary key fingerprint: 9957 4B4D 3474 90E7 9D98  D624 BDBE 7B27 C0DE 3057

* remotes/cody/tags/block-pull-request:
  qemu-options: Fix broken sheepdog URL
  mirror: do not increase offset during initial zero_or_discard phase
  QAPI: Fix blockdev-add example documentation
  iscsi: Add blockdev-add support
  iscsi: Add timeout option
  iscsi: Add header-digest option
  iscsi: Add initiator-name option
  iscsi: Handle -iscsi user/password in bdrv_parse_filename()
  iscsi: Split URL into individual options
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

The sheepdog URL is broken twice: First it uses a duplicated
http:// prefix, second the website seems to have moved to
https://sheepdog.github.io/sheepdog/ instead.
Signed-off-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

If explicit zeroing out before mirroring is required for the target image,
it moves the block job offset counter to EOF, then offset and len counters
count the image size twice. There is no harm but stats are confusing,
specifically the progress of the operation is always reported as 99% by
management tools.

The patch skips offset increase for the first "technical" pass over the
image. This should not cause any further harm.
Signed-off-by: NAnton Nefedov <anton.nefedov@virtuozzo.com>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1486045515-8009-1-git-send-email-den@openvz.org
CC: Jeff Cody <jcody@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
CC: Eric Blake <eblake@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

Signed-off-by: NJeff Cody <jcody@redhat.com>

This adds blockdev-add support for iscsi devices.
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

This was previously only available with -iscsi. Again, after this patch,
the -iscsi option only takes effect if an URL is given. New users are
supposed to use the new driver-specific option.

All -iscsi options have a corresponding driver-specific option for the
iscsi block driver now.
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

This was previously only available with -iscsi. Again, after this patch,
the -iscsi option only takes effect if an URL is given. New users are
supposed to use the new driver-specific option.
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

This was previously only available with -iscsi. Again, after this patch,
the -iscsi option only takes effect if an URL is given. New users are
supposed to use the new driver-specific option.
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

This splits the logic in the old parse_chap() function into a part that
parses the -iscsi options into the new driver-specific options, and
another part that actually applies those options (called apply_chap()
now).

Note that this means that username and password specified with -iscsi
only take effect when a URL is provided. This is intentional, -iscsi is
a legacy interface only supported for compatibility, new users should
use the proper driver-specific options.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

This introduces a .bdrv_parse_filename handler for iscsi which parses an
URL if given and translates it to individual options.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NJeff Cody <jcody@redhat.com>

Changes to -drive without if= and with if=scsi

# gpg: Signature made Tue 21 Feb 2017 12:22:35 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-block-2017-02-21:
  hw/i386: Deprecate -drive if=scsi with PC machine types
  hw: Deprecate -drive if=scsi with non-onboard HBAs
  hw/scsi: Concentrate -drive if=scsi auto-create in one place
  hw: Drop superfluous special checks for orphaned -drive
  blockdev: Make orphaned -drive fatal
  blockdev: Improve message for orphaned -drive
  hw/arm/highbank: Default -drive to if=ide instead of if=scsi
  hw: Default -drive to if=none instead of scsi when scsi cannot work
  hw: Default -drive to if=none instead of ide when ide cannot work
  hw/arm/cubieboard hw/arm/xlnx-ep108: Fix units_per_default_bus
  hw: Default -drive to if=ide explicitly where it works
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

The PC machines (pc-q35-* pc-i440fx-* pc-* isapc xenfv) automatically
create lsi53c895a SCSI HBAs and SCSI devices to honor -drive if=scsi.
For giggles, try -drive if=scsi,bus=25,media=cdrom --- this makes QEMU
create 25 of them.

lsi53c895a is thoroughly obsolete (PCI Ultra2 SCSI, ca. 2000), and
currently has no maintainer in QEMU.  megasas is a better choice,
except with old OSes that lack drivers.  virtio-scsi is a much better
choice when you have a driver, but only (newish) Linux comes with one
in the box.  There is no good default that works for all guests.

Encourage users to pick a non-obsolete SCSI HBA that works for them by
deprecating -drive if=scsi.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1487161136-9018-4-git-send-email-armbru@redhat.com>
Acked-By: NPaolo Bonzini <pbonzini@redhat.com>

Block backends defined with "-drive if=T" with T other than "none" are
meant to be picked up by machine initialization code: a suitable
frontend gets created and wired up automatically.

Drives defined with if=scsi are also picked up by SCSI HBAs added with
-device, unlike other interface types.  Deprecate this usage, as follows.

Create the frontends for onboard HBAs in machine initialization code,
exactly like we do for if=ide and other interface types.  Change
scsi_legacy_handle_cmdline() to create a frontend only when it's still
missing, and warn that this usage is deprecated.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1487161136-9018-3-git-send-email-armbru@redhat.com>

The logic to create frontends for -drive if=scsi is in SCSI HBAs.  For
all other interface types, it's in machine initialization code.

A few machine types create the SCSI HBAs necessary for that.  That's
also not done for other interface types.

I'm going to deprecate these SCSI eccentricities.  In preparation for
that, create the frontends in main() instead of the SCSI HBAs, by
calling new function scsi_legacy_handle_cmdline() there.

Note that not all SCSI HBAs create frontends.  Take care not to change
that.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1487161136-9018-2-git-send-email-armbru@redhat.com>
Acked-By: NPaolo Bonzini <pbonzini@redhat.com>

We've traditionally rejected orphans here and there, but not
systematically.  For instance, the sun4m machines have an onboard SCSI
HBA (bus=0), and have always rejected bus>0.  Other machines with an
onboard SCSI HBA don't.

Commit a66c9dc7 made all orphans trigger a warning, and the previous
commit turned this into an error.  The checks "here and there" are now
redundant.  Drop them.

Note that the one in mips_jazz.c was wrong: it rejected bus > MAX_FD,
but MAX_FD is the number of floppy drives per bus.

Error messages change from

    $ qemu-system-x86_64 -drive if=ide,bus=2
    qemu-system-x86_64: Too many IDE buses defined (3 > 2)
    $ qemu-system-mips64 -M magnum,accel=qtest -drive if=floppy,bus=2,id=fd1
    qemu: too many floppy drives
    $ qemu-system-sparc -M LX -drive if=scsi,bus=1
    qemu: too many SCSI bus

to

    $ qemu-system-x86_64 -drive if=ide,bus=2
    qemu-system-x86_64: -drive if=ide,bus=2: machine type does not support if=ide,bus=2,unit=0
    $ qemu-system-mips64 -M magnum,accel=qtest -drive if=floppy,bus=2,id=fd1
    qemu-system-mips64: -drive if=floppy,bus=2,id=fd1: machine type does not support if=floppy,bus=2,unit=0
    $ qemu-system-sparc -M LX -drive if=scsi,bus=1
    qemu-system-sparc: -drive if=scsi,bus=1: machine type does not support if=scsi,bus=1,unit=0

Cc: John Snow <jsnow@redhat.com>
Cc: "Hervé Poussineau" <hpoussin@reactos.org>
Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1487153147-11530-9-git-send-email-armbru@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>

Block backends defined with "-drive if=T" with T other than "none" are
meant to be picked up by machine initialization code: a suitable
frontend gets created and wired up automatically.

If machine initialization code doesn't comply, the block backend
remains unused.  This triggers a warning since commit a66c9dc7, v2.2.0.
Drives created by default are exempted; use -nodefaults to get rid of
them.

Turn this warning into an error.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1487153147-11530-8-git-send-email-armbru@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>

We warn when a -drive isn't supported by the machine type (commit
a66c9dc7):

    $ qemu-system-x86_64 -S -display none -drive if=mtd
    Warning: Orphaned drive without device: id=mtd0,file=,if=mtd,bus=0,unit=0

Improve this to point to the offending bit of configuration:

    qemu-system-x86_64: -drive if=mtd: warning: machine type does not support if=mtd,bus=0,unit=0

Especially nice when it's hidden behind -readconfig foo.cfg:

    qemu-system-x86_64:foo.cfg:140: warning: machine type does not support if=mtd,bus=0,unit=0
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1487153147-11530-7-git-send-email-armbru@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>

These machines have no onboard SCSI HBA, and no way to plug one.
-drive if=scsi therefore cannot work.  They do have an onboard IDE
controller (sysbus-ahci), but fail to honor if=ide.

Change their default to if=ide, and add a TODO comment on what needs
to be done to actually honor -drive if=ide.

Cc: Rob Herring <robh@kernel.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm@nongnu.org
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Message-Id: <1487153147-11530-6-git-send-email-armbru@redhat.com>

Block backends defined with -drive if=scsi are meant to be picked up
by machine initialization code: a suitable frontend gets created and
wired up automatically.

if=scsi drives not picked up that way can still be used with -device
as if they had if=none, but that's unclean and best avoided.  Unused
ones produce an "Orphaned drive without device" warning.

A few machine types default to if=scsi, even though they don't
actually have a SCSI HBA.  This makes no sense.  Change their default
to if=none.  Affected machines:

* aarch64/arm: realview-pbx-a9 vexpress-a9 vexpress-a15 xilinx-zynq-a9

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: qemu-arm@nongnu.org
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Reviewed-by: NAlistair Francis <alistair.francis@xilinx.com>
Message-Id: <1487153147-11530-5-git-send-email-armbru@redhat.com>

Block backends defined with -drive if=ide are meant to be picked up by
machine initialization code: a suitable frontend gets created and
wired up automatically.

if=ide drives not picked up that way can still be used with -device as
if they had if=none, but that's unclean and best avoided.  Unused ones
produce an "Orphaned drive without device" warning.

-drive parameter "if" is optional, and the default depends on the
machine type.  If a machine type doesn't specify a default, the
default is "ide".

Many machine types implicitly default to if=ide that way, even though
they don't actually have an IDE controller.  This makes no sense.

Change the implicit default to if=none.  Affected machines:

* all targets: none
* aarch64/arm: akita ast2500 canon cheetah collie connex imx25
  integratorcp kzm lm3s6965evb lm3s811evb mainstone musicpal n800 n810
  netduino2 nuri palmetto realview romulus sabrelite smdkc210 sx1 sx1
  verdex z2
* cris: axis-dev88
* i386/x86_64: xenpv
* lm32: lm32-evr lm32-uclinux milkymist
* m68k: an5206 dummy mcf5208evb
* microblaze/microblazeel: petalogix-ml605 petalogix-s3adsp1800
* mips/mips64/mips64el/mipsel: mipssim
* moxie: moxiesim
* or32: or32-sim
* ppc/ppc64/ppcemb: bamboo ref405ep taihu virtex-ml507
* ppc/ppc64: mpc8544ds ppce500
* sh4/sh4eb: shix
* sparc: leon3_generic
* sparc64: niagara
* tricore: tricore_testboard
* unicore32: puv3
* xtensa/xtensaeb: kc705 lx200 lx60 ml605 sim

None of these machines have an IDE controller, let alone code to
honor if=ide.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm@nongnu.org
Cc: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: xen-devel@lists.xensource.com
Cc: Michael Walle <michael@walle.cc>
Cc: Laurent Vivier <laurent@vivier.eu>
Cc: Anthony Green <green@moxielogic.com>
Cc: Jia Liu <proljc@gmail.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: qemu-ppc@nongnu.org
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Fabien Chouteau <chouteau@adacore.com>
Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Cc: Artyom Tarasenko <atar4qemu@gmail.com>
Cc: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Acked-By: NArtyom Tarasenko <atar4qemu@gmail.com>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Message-Id: <1487153147-11530-4-git-send-email-armbru@redhat.com>

Machine types cubieboard, xlnx-ep108, xlnx-zcu102 have an onboard AHCI
controller, but neglect to set their MachineClass member
units_per_default_bus = 1.  This permits -drive if=ide,unit=1, which
makes no sense for AHCI.  It also screws up index=N for odd N, because
it gets desugared to unit=1,bus=N/2

Doesn't really matter, because these machine types fail to honor
-drive if=ide.  Add the missing units_per_default_bus = 1 anyway,
along with a TODO comment on what needs to be done for -drive if=ide.

Also set block_default_type = IF_IDE explicitly.  It's currently the
default, but the next commit will change it to something more
sensible, and we want to keep the IF_IDE default for these three
machines.  See also the previous commit.

Cc: Beniamino Galvani <b.galvani@gmail.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm@nongnu.org
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Acked-by: NAlistair Francis <alistair.francis@xilinx.com>
Message-Id: <1487153147-11530-3-git-send-email-armbru@redhat.com>

Block backends defined with -drive if=ide are meant to be picked up by
machine initialization code: a suitable frontend gets created and
wired up automatically.

if=ide drives not picked up that way can still be used with -device as
if they had if=none, but that's unclean and best avoided.  Unused ones
produce an "Orphaned drive without device" warning.

-drive parameter "if" is optional, and the default depends on the
machine type.  If a machine type doesn't specify a default, the
default is "ide".

Many machine types default to if=ide, even though they don't actually
have an IDE controller.  A future patch will change these defaults to
something more sensible.  To prepare for it, this patch makes default
"ide" explicit for the machines that actually pick up if=ide drives:

* alpha: clipper
* arm/aarch64: spitz borzoi terrier tosa
* i386/x86_64: generic-pc-machine (with concrete subtypes pc-q35-*
  pc-i440fx-* pc-* isapc xenfv)
* mips64el: fulong2e
* mips/mipsel/mips64el: malta mips
* ppc/ppc64: mac99 g3beige prep
* sh4/sh4eb: r2d
* sparc64: sun4u sun4v

Note that ppc64 machine powernv already sets an "ide" default
explicitly.  Its IDE controller isn't implemented, yet.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Message-Id: <1487153147-11530-2-git-send-email-armbru@redhat.com>

Pull request

v2:
 * Rebased to resolve scsi conflicts

# gpg: Signature made Tue 21 Feb 2017 11:56:24 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: (24 commits)
  coroutine-lock: make CoRwlock thread-safe and fair
  coroutine-lock: add mutex argument to CoQueue APIs
  coroutine-lock: place CoMutex before CoQueue in header
  test-aio-multithread: add performance comparison with thread-based mutexes
  coroutine-lock: add limited spinning to CoMutex
  coroutine-lock: make CoMutex thread-safe
  block: document fields protected by AioContext lock
  async: remove unnecessary inc/dec pairs
  aio-posix: partially inline aio_dispatch into aio_poll
  block: explicitly acquire aiocontext in aio callbacks that need it
  block: explicitly acquire aiocontext in bottom halves that need it
  block: explicitly acquire aiocontext in callbacks that need it
  block: explicitly acquire aiocontext in timers that need it
  aio: push aio_context_acquire/release down to dispatching
  qed: introduce qed_aio_start_io and qed_aio_next_io_cb
  blkdebug: reschedule coroutine on the AioContext it is running on
  coroutine-lock: reschedule coroutine on the AioContext it was running on
  nbd: convert to use qio_channel_yield
  io: make qio_channel_yield aware of AioContexts
  io: add methods to set I/O handlers on AioContext
  ...
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

This adds a CoMutex around the existing CoQueue.  Because the write-side
can just take CoMutex, the old "writer" field is not necessary anymore.
Instead of removing it altogether, count the number of pending writers
during a read-side critical section and forbid further readers from
entering.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 20170213181244.16297-7-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

All that CoQueue needs in order to become thread-safe is help
from an external mutex.  Add this to the API.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 20170213181244.16297-6-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

This will avoid forward references in the next patch.  It is also
more logical because CoQueue is not anymore the basic primitive.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 20170213181244.16297-5-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Add two implementations of the same benchmark as the previous patch,
but using pthreads.  One uses a normal QemuMutex, the other is Linux
only and implements a fair mutex based on MCS locks and futexes.
This shows that the slower performance of the 5-thread case is due to
the fairness of CoMutex, rather than to coroutines.  If fairness does
not matter, as is the case with two threads, CoMutex can actually be
faster than pthreads.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 20170213181244.16297-4-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Running a very small critical section on pthread_mutex_t and CoMutex
shows that pthread_mutex_t is much faster because it doesn't actually
go to sleep.  What happens is that the critical section is shorter
than the latency of entering the kernel and thus FUTEX_WAIT always
fails.  With CoMutex there is no such latency but you still want to
avoid wait and wakeup.  So introduce it artificially.

This only works with one waiters; because CoMutex is fair, it will
always have more waits and wakeups than a pthread_mutex_t.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 20170213181244.16297-3-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

This uses the lock-free mutex described in the paper '"Blocking without
Locking", or LFTHREADS: A lock-free thread library' by Gidenstam and
Papatriantafilou.  The same technique is used in OSv, and in fact
the code is essentially a conversion to C of OSv's code.

[Added missing coroutine_fn in tests/test-aio-multithread.c.
--Stefan]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Message-id: 20170213181244.16297-2-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-19-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Pull the increment/decrement pair out of aio_bh_poll and into the
callers.
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-18-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

This patch prepares for the removal of unnecessary lockcnt inc/dec pairs.
Extract the dispatching loop for file descriptor handlers into a new
function aio_dispatch_handlers, and then inline aio_dispatch into
aio_poll.

aio_dispatch can now become void.
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-17-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-16-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-15-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

This covers both file descriptor callbacks and polling callbacks,
since they execute related code.
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-14-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-13-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

The AioContext data structures are now protected by list_lock and/or
they are walked with FOREACH_RCU primitives.  There is no need anymore
to acquire the AioContext for the entire duration of aio_dispatch.
Instead, just acquire it before and after invoking the callbacks.
The next step is then to push it further down.
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-12-pbonzini@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>