tests: Functions bus_foreach and device_find from libqos virtio API

Virtio header has been changed to compile and work with a real device.
Functions bus_foreach and device_find have been implemented for PCI.
Virtio-blk test case now opens a fake device.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
tests: Add virtio device initialization

Add functions to read and write virtio header fields.
Add status bit setting in virtio-blk-device.

Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
libqos: Added basic virtqueue support to virtio implementation

Add status changing and feature negotiation.
Add basic virtqueue support for adding and sending virtqueue requests.
Add ISR checking.

[Squashed request endianness fix by Greg Kurz <gkurz@linux.vnet.ibm.com>
--Stefan]

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
libqos: Added indirect descriptor support to virtio implementation

Add functions necessary for working with indirect descriptors.
Add test using new functions.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
libqos: Added test case for configuration changes in virtio-blk test

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
libqos: Added MSI-X support

Added MSI-X support for qtest PCI.
Added MSI-X support for virtio-pci.
Added MSI-X test case in virtio-blk-test.

Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
libqos: Added EVENT_IDX support

Added avail_event and NO_NOTIFY check before notifying.
Added used_event setting.

Signed-off-by: Marc Marí <marc.mari.barcelo@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>