At the moment the following QEMU command line triggers an assertion
failure (minimal reproducer by Cole):

  qemu-system-aarch64 \
    -machine virt-2.6,accel=tcg \
    -nodefaults \
    -no-user-config \
    -nographic -monitor stdio \
    -device virtio-scsi-device,id=scsi0 \
    -device virtio-scsi-device,id=scsi1 \
    -drive file=foo.img,format=raw,if=none,id=d0 \
    -device scsi-hd,bus=scsi0.0,drive=d0 \
    -drive file=foo.img,format=raw,if=none,id=d1 \
    -device scsi-hd,bus=scsi1.0,drive=d1

  qemu-system-aarch64: migration/savevm.c:615:
  vmstate_register_with_alias_id:
  Assertion `!se->compat || se->instance_id == 0' failed.

The reason is that the vmstate sections for the two scsi-hd devices are
not uniquely identifiable by name.

The direct parent buses of the scsi-hd devices -- scsi0.0 and scsi1.0 --
support the BusClass.get_dev_path member function. scsibus_get_dev_path()
formats a device path prefix with the help of its topologically parent
bus, and then appends the chan:id:lun triplet to it. For both scsi-hd
devices, this triplet is 0:0:0.

(Here we use "device path" in the QEMU migration sense, for vmstate
section identification, not in the OFW or UEFI device path senses.)

The virtio-scsi HBA is plugged into the virtio-mmio bus (implemented by
the internal VirtIOMMIOProxy device). This bus class
(TYPE_VIRTIO_MMIO_BUS) inherits, as its get_dev_path() member function,
the virtio_bus_get_dev_path() method from its parent class
(TYPE_VIRTIO_BUS).

virtio_bus_get_dev_path() does not format any kind of device address on
its own; "virtio addresses" are transport-specific. Therefore
virtio_bus_get_dev_path() asks the topologically parent bus of the proxy
object (implementing the specific virtio transport) to format the address
of the proxy object.

(For virtio-pci devices (where the proxy is an instance of VirtIOPCIProxy,
plugged into a PCI bus), this ends up in pcibus_get_dev_path().)

However, VirtIOMMIOProxy is usually (in practice: always) plugged into
"main-system-bus", the singleton TYPE_SYSTEM_BUS object. This BusClass
does not support formatting QEMU vmstate device paths at all (as
SysBusDevice objects can have zero or more IO ports and zero or more MMIO
regions). Hence the formatting request delegated from
virtio_bus_get_dev_path() gets answered with NULL.

The end result is that the two scsi-hd devices end up with the same device
path "0:0:0", which triggers the assert.

We can solve this by recognizing that virtio-mmio transports are
distinguished from each other by their base addresses in MMIO address
space. Implement virtio_mmio_bus_get_dev_path() as follows:

(1) The virtio device whose devpath is to be formatted resides on a
    virtio-mmio bus that is implemented by a VirtIOMMIOProxy object. Ask
    the parent bus of VirtIOMMIOProxy to format the device path of
    VirtIOMMIOProxy, as a path prefix. (This is identical to what
    virtio_bus_get_dev_path() does.)

(2) Append the base address of VirtIOMMIOProxy to the device path, such
    as:
    - virtio-mmio@000000000a003e00,
    - virtio-mmio@000000000a003c00.

Given that these device paths are placed in the migration stream, step (2)
above, if done unconditionally, would break migration. So make that step
conditional on a new VirtIOMMIOProxy property, which is enabled for 2.7
machine types and later.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Cole Robinson <crobinso@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Kevin Zhao <kevin.zhao@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Tom Hanson <thomas.hanson@linaro.org>
Reported-by: NKevin Zhao <kevin.zhao@linaro.org>
Reviewed-by: NAndrew Jones <drjones@redhat.com>
Signed-off-by: NLaszlo Ersek <lersek@redhat.com>
Message-id: 1467739394-28357-1-git-send-email-lersek@redhat.com
Fixes: https://bugs.launchpad.net/qemu/+bug/1594239Signed-off-by: NLaszlo Ersek <lersek@redhat.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Convert to the new interface.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1453832250-766-15-git-send-email-peter.maydell@linaro.org

For virtio-1 devices, we allow a more complex queue layout that doesn't
require descriptor table and rings on a physically-contigous memory area:
add virtio_queue_set_rings() to allow transports to set this up.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>

set_host_notifier and set_guest_notifiers supported by virtio-mmio now.
Most code copied from virtio-pci.

This makes it possible to use vhost-net with virtio-mmio,
improving performance by about 30%.

The kvm-arm does not yet support irqfd, need to fix the hard-coded part after
kvm-arm gets irqfd support.
Signed-off-by: NYing-Shiuan Pan <yingshiuan.pan@gmail.com>
Signed-off-by: NPavel Fedin <p.fedin@samsung.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

VIRTIO_PCI_QUEUE_MAX is not only used for pci, so rename it be generic.

Cc: Amit Shah <amit.shah@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.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>

Nearly all transports have been offering VIRTIO_F_NOTIFY_ON_EMPTY,
s390-virtio being the exception. There's no reason why it shouldn't
offer it as well, though (handling is done in core anyway), so let's
move it to the common virtio features.

While we're changing it anyway, fix the indentation for the
DEFINE_VIRTIO_COMMON_FEATURES macro.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

Move host_features from the individual transport proxies into
the virtio device. Transports may continue to add feature bits
during device plugging.

This should it make easier to offer different sets of host features
for virtio-1/transitional support.
Tested-by: NShannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

Add virtio_{add,clear}_feature helper functions for manipulating a
feature bits variable. This has some benefits over open coding:
- add check that the bit is in a sane range
- make it obvious at a glance what is going on
- have a central point to change when we want to extend feature bits

Convert existing code manipulating features to use the new helpers.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

Bus by default is not hotpluggable.
virtio-mmio-bus and its parent types do not set allow_hotplug
anywhere explicitly, so remove not needed field access
and wrapper along with it.
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>

Both 'indirect_desc' and 'event_idx' are bus independent features,
and they should be enabled for mmio devices too.

On arm64 quad core VM(qemu-kvm), the patch can increase block I/O
performance a lot with latest linux tree:
        - without the patch: 14K IOPS
        - with the patch: 34K IOPS

fio script:
        [global]
        direct=1
        bsrange=4k-4k
        timeout=10
        numjobs=4
        ioengine=libaio
        iodepth=64

        filename=/dev/vdc
        group_reporting=1

        [f1]
        rw=randread

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: NMing Lei <ming.lei@canonical.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

The vdev field is complicated to synchronize.  Just access the
BusState's list of children.

Cc: qemu-stable@nongnu.org
Acked-by: NAndreas Faerber <afaerber@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

To be passed to object_initialize().

Since commit 39355c38 the argument is
void*, so drop some superfluous (BusState *) casts or direct parent
field usages.
Signed-off-by: NAndreas Färber <afaerber@suse.de>

To be passed to qbus_create_initialize().
Reviewed-by: NWenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>

The virtio-mmio spec says that QueueNumMax must read zero for queues
which are unavailable; implement this, rather than always returning
VIRTQUEUE_MAX_SIZE.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1374853288-9912-3-git-send-email-peter.maydell@linaro.org
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>

The category will be used to sort the devices displayed in
the command line help.
Signed-off-by: NMarcel Apfelbaum <marcel.a@redhat.com>
Message-id: 1375107465-25767-4-git-send-email-marcel.a@redhat.com
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Add support for the generic MMIO based virtio transport.

This patch includes some fixes for bugs spotted by
Ying-Shiuan Pan <yspan@itri.org.tw>.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NKONRAD Frederic <fred.konrad@greensocs.com>
Message-id: 1373977512-28932-6-git-send-email-peter.maydell@linaro.org
[Fred changes: updated to new virtio-bus mechanisms]
Signed-off-by: NKONRAD Frederic <fred.konrad@greensocs.com>
[PMM changes:
 * fixed trivial makefile conflict
 * removed unused int_enable
 * host_features doesn't need migrating
 * reset guest accessible state in the reset function
 * minor style fixes like extra blank lines
 * RAZ/WI if there's no backend
 * made transport size 0x200, in line with kvmtool
 * set has_variable_vring_alignment
]