Temporarily modify hw/Makefile.objs to cherrypick ef4929fb3c25e03deca76c7f5d22fba08edf864f
dataplane: use linux-headers/ for virtio includes

The hw/dataplane/vring.c code includes linux/virtio_ring.h.  Ensure that
we use linux-headers/ instead of the system-wide headers, which may be
out-of-date on older distros.

This resolves the following build error on Debian 6:

  CC    hw/dataplane/vring.o
cc1: warnings being treated as errors
hw/dataplane/vring.c: In function 'vring_enable_notification':
hw/dataplane/vring.c:71: error: implicit declaration of function 'vring_avail_event'
hw/dataplane/vring.c:71: error: nested extern declaration of 'vring_avail_event'
hw/dataplane/vring.c:71: error: lvalue required as left operand of assignment

Note that we now build dataplane/ for each target instead of only once.
There is no way around this since linux-headers/ is only available for
per-target objects - and it's how virtio, vfio, kvm, and friends are
built.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit ef4929fb3c25e03deca76c7f5d22fba08edf864f)
Manually revert 374a479d79cc624722523aca71c17fd5fc53a4ac
dataplane: extract virtio-blk read/write processing into do_rdwr_cmd()

Extract code for read/write command processing into do_rdwr_cmd().  This
brings together pieces that are spread across process_request().

The real motivation is to set the stage for handling misaligned
requests, which the next patch tackles.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit b5ef1aab945c1b04740574064b13eb93f1572587)
dataplane: handle misaligned virtio-blk requests

O_DIRECT on Linux has alignment requirements on I/O buffers and
misaligned requests result in -EINVAL.  The Linux virtio_blk guest
driver usually submits aligned requests so I forgot to handle misaligned
requests.

It turns out that virtio-win guest drivers submit misaligned requests.
Handle them using a bounce buffer that meets alignment requirements.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit de0161c0d553f2aaf6118ca87f978a5e6b4a9732)
dataplane: fix build breakage on set_guest_notifiers()

virtio_pci_set_guest_notifiers() now takes an additional argument to
specify the number of virtqueues to assign a guest notifier for. This
causes a build breakage for CONFIG_VIRTIO_BLK_DATA_PLANE builds:

/home/mdroth/w/qemu2.git/hw/dataplane/virtio-blk.c: In function
‘virtio_blk_data_plane_start’:
/home/mdroth/w/qemu2.git/hw/dataplane/virtio-blk.c:451:47: error: too
few arguments to function ‘s->vdev->binding->set_guest_notifiers’
/home/mdroth/w/qemu2.git/hw/dataplane/virtio-blk.c: In function
‘virtio_blk_data_plane_stop’:
/home/mdroth/w/qemu2.git/hw/dataplane/virtio-blk.c:511:5: error: too few
arguments to function ‘s->vdev->binding->set_guest_notifiers’
make[1]: *** [hw/dataplane/virtio-blk.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [subdir-x86_64-softmmu] Error 2

Fix this by passing 1 as the number of virtqueues to assign notifiers
for.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit b8bec49cccbf8e34558371df60e7e64419c4fde9)
dataplane: avoid reentrancy during virtio_blk_data_plane_stop()

When dataplane is stopping, the s->vdev->binding->set_host_notifier(...,
false) call can invoke the virtqueue handler if an ioeventfd
notification is pending.  This causes hw/virtio-blk.c to invoke
virtio_blk_data_plane_start() before virtio_blk_data_plane_stop()
returns!

The result is that we try to restart dataplane while trying to stop it
and the following assertion is raised:

  msix_set_mask_notifier: Assertion `!dev->msix_mask_notifier' failed.

Although the code was intended to prevent this scenario, the s->started
boolean isn't enough.  Add s->stopping so that we can postpone clearing
s->started until we've completely stopped dataplane.

This way, virtqueue handler calls during virtio_blk_data_plane_stop()
are ignored.  When dataplane is legitimately started again later we
already self-kick ourselves to resume processing.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit cd7fdfe59f4f965665dcd9868fe3764f5256d6aa)
dataplane: support viostor virtio-pci status bit setting

The viostor virtio-blk driver for Windows does not use the
VIRTIO_CONFIG_S_DRIVER bit.  It only sets the VIRTIO_CONFIG_S_DRIVER_OK
bit.

The viostor driver refreshes the virtio-pci status byte sometimes while
the guest is running.  We misinterpret 0x4 (VIRTIO_CONFIG_S_DRIVER_OK)
as an indication that virtio-blk-data-plane should be stopped since 0x2
(VIRTIO_CONFIG_S_DRIVER) is missing.  The result is that the device
becomes unresponsive.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit cf139388ad5b39228793f34eea99e0ea9a2924aa)