[Qemu-devel] Assigning a new virtio block device (-drive)

[Qemu-devel] Assigning a new virtio block device (-drive)

[Leib, David]

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Hi,
I am trying to assign a new virtio block device in addition to a normal virtio block device who are accessing exactly the same cdrom drive ("/dev/sr0") because I additionaly want to access the block device in my way by manually calling the virtqueue_pop and virtqueue_push and not the normal way they are called.
At the kvm startup I am assigning this additional qemu rblock device in the vm_config_groups by adding a new QemuOptsList:

static QemuOptsList qemu_ablock_opts = {
    .name = "ablock",
    .head = QTAILQ_HEAD_INITIALIZER(qemu_ablock_opts.head),
    .desc = {
                        ..... normal options like the original virtio block device .....
        { /* end of list */ }
    },
};

and insert the same data like the normal virtio block device ("file=/dev/sr0" and "if=virtio") in qemu_config.c.
After that I am calling the normal drive_init_func  ("vl.c") with this command :

qemu_opts_foreach(qemu_find_opts("ablock"), drive_init_func, &machine->use_scsi, 1);

I also added PCIDeviceInfo to the virtio_info array who looks like this:
    {
                .qdev.name = "additional_blk_pci",
                .qdev.alias = "additional-blk",
                .qdev.size = sizeof(VirtIOPCIProxy),
                .init      = virtio_blk_init_pci_additional,
                .exit      = virtio_blk_exit_pci,
                .vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET,
                .device_id = PCI_DEVICE_ID_VIRTIO_BLOCK,
                .revision  = VIRTIO_PCI_ABI_VERSION,
                .class_id  = PCI_CLASS_STORAGE_SCSI,
                .qdev.props = (Property[]) {
                        DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
                        DEFINE_BLOCK_PROPERTIES(VirtIOPCIProxy, block),
                        DEFINE_PROP_STRING("serial", VirtIOPCIProxy, block_serial),
                        DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
                                                        VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
                        DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
                        DEFINE_VIRTIO_BLK_FEATURES(VirtIOPCIProxy, host_features),
                        DEFINE_PROP_END_OF_LIST(),
                },
                .qdev.reset = virtio_pci_reset,
        },
It is completely the same like the normal "virtio-blk-pci" except the .init function that I replaced with my own init-function.
My problem now is that this init-function is never called when I am starting up the kvm. It only calling the the init-function of "virtio-blk-pci" two times and my PCIDeviceInfo init-function is completely ignored.
The initialisation of all virtio_info's in "virtio-pci.c" works fine but my init-function is never used.
I tried to initialise only my "additional-virtio-blk-pci" device but is still calling the init-function from "virtio-blk-pci".
I hope somebody can give me idea where the problem is.
Many thanks,


David Leib
SAP Research Belfast
SAP (UK) Limited   I   The Concourse   I   Queen's Road   I   Queen's Island   I   Belfast BT3 9DT

mailto: david.leib@sap.com<mailto:mary.clarke@sap.com>  I   www.sap.com/research<http://www.sap.com/research>

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Re: [Qemu-devel] Assigning a new virtio block device (-drive)

[Paolo Bonzini]

On 10/27/2011 02:47 PM, Leib, David wrote:
> and insert the same data like the normal virtio block device
> (“file=/dev/sr0” and “if=virtio”) in qemu_config.c.

I'm not sure what you are doing wrong exactly, but try using if=none and 
creating the device separately with -device.  You shouldn't need the new 
"ablock" QemuOpts.

Paolo

Re: [Qemu-devel] Assigning a new virtio block device (-drive)

[Markus Armbruster]

"Leib, David" <david.leib@sap.com> writes:

> Hi,
> I am trying to assign a new virtio block device in addition to a normal virtio block device who are accessing exactly the same cdrom drive ("/dev/sr0") because I additionaly want to access the block device in my way by manually calling the virtqueue_pop and virtqueue_push and not the normal way they are called.
> At the kvm startup I am assigning this additional qemu rblock device in the vm_config_groups by adding a new QemuOptsList:
>
> static QemuOptsList qemu_ablock_opts = {
>     .name = "ablock",
>     .head = QTAILQ_HEAD_INITIALIZER(qemu_ablock_opts.head),
>     .desc = {
>                         ..... normal options like the original virtio block device .....
>         { /* end of list */ }
>     },
> };
>
> and insert the same data like the normal virtio block device ("file=/dev/sr0" and "if=virtio") in qemu_config.c.
> After that I am calling the normal drive_init_func  ("vl.c") with this command :
>
> qemu_opts_foreach(qemu_find_opts("ablock"), drive_init_func, &machine->use_scsi, 1);

Your new qemu_ablock_opts won't do a thing without something that writes
configuration data to it.  For qemu_drive_opts, that's drive_def(),
which runs on behalf of -drive and drive hot plug.

> I also added PCIDeviceInfo to the virtio_info array who looks like this:
>     {
>                 .qdev.name = "additional_blk_pci",
>                 .qdev.alias = "additional-blk",
>                 .qdev.size = sizeof(VirtIOPCIProxy),
>                 .init      = virtio_blk_init_pci_additional,
>                 .exit      = virtio_blk_exit_pci,
>                 .vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET,
>                 .device_id = PCI_DEVICE_ID_VIRTIO_BLOCK,
>                 .revision  = VIRTIO_PCI_ABI_VERSION,
>                 .class_id  = PCI_CLASS_STORAGE_SCSI,
>                 .qdev.props = (Property[]) {
>                         DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
>                         DEFINE_BLOCK_PROPERTIES(VirtIOPCIProxy, block),
>                         DEFINE_PROP_STRING("serial", VirtIOPCIProxy, block_serial),
>                         DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
>                                                         VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
>                         DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
>                         DEFINE_VIRTIO_BLK_FEATURES(VirtIOPCIProxy, host_features),
>                         DEFINE_PROP_END_OF_LIST(),
>                 },
>                 .qdev.reset = virtio_pci_reset,
>         },
> It is completely the same like the normal "virtio-blk-pci" except the .init function that I replaced with my own init-function.
> My problem now is that this init-function is never called when I am starting up the kvm. It only calling the the init-function of "virtio-blk-pci" two times and my PCIDeviceInfo init-function is completely ignored.
> The initialisation of all virtio_info's in "virtio-pci.c" works fine but my init-function is never used.
> I tried to initialise only my "additional-virtio-blk-pci" device but is still calling the init-function from "virtio-blk-pci".
> I hope somebody can give me idea where the problem is.

Try -device additional_blk_pci.  Check out docs/qdev-device-use.txt for
how to go from -drive if=virtio (which doesn't use your device) to
-device (which should be able to use your device).