Re: [PATCH v2 7/7] libqos: add VIRTIO PCI 1.0 support

[Thomas Huth]

On 11/10/2019 10.56, Stefan Hajnoczi wrote:
> Implement the VIRTIO 1.0 virtio-pci interface.  The main change here is
> that the register layout is no longer a fixed layout in BAR 0.  Instead
> we have to iterate of PCI Capabilities to find descriptions of where
> various registers are located.  The vring registers are also more
> fine-grained, allowing for more flexible vring layouts, but we don't
> take advantage of that.
> 
> Note that test cases do not negotiate VIRTIO_F_VERSION_1 yet and are
> therefore not running in VIRTIO 1.0 mode.
> 
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
>  tests/Makefile.include           |   1 +
>  tests/libqos/virtio-pci-modern.h |  17 ++
>  tests/libqos/virtio-pci.h        |  10 +
>  tests/libqos/virtio-pci-modern.c | 412 +++++++++++++++++++++++++++++++
>  tests/libqos/virtio-pci.c        |   6 +-
>  5 files changed, 445 insertions(+), 1 deletion(-)
>  create mode 100644 tests/libqos/virtio-pci-modern.h
>  create mode 100644 tests/libqos/virtio-pci-modern.c
[...]
> +static bool probe_device_type(QVirtioPCIDevice *dev)
> +{
> +    uint16_t vendor_id;
> +    uint16_t device_id;
> +
> +    /* "Drivers MUST match devices with the PCI Vendor ID 0x1AF4" */
> +    vendor_id = qpci_config_readw(dev->pdev, PCI_VENDOR_ID);
> +    if (vendor_id != 0x1af4) {
> +        return false;
> +    }
> +
> +    /*
> +     * "Any PCI device with ... PCI Device ID 0x1000 through 0x107F inclusive
> +     * is a virtio device"
> +     */
> +    device_id = qpci_config_readw(dev->pdev, PCI_DEVICE_ID);
> +    if (device_id < 0x1000 || device_id > 0x107f) {
> +        return false;
> +    }
> +
> +    /*
> +     * "Devices MAY utilize a Transitional PCI Device ID range, 0x1000 to
> +     * 0x103F depending on the device type"
> +     */
> +    if (device_id < 0x1040) {
> +        /*
> +         * "Transitional devices MUST have the PCI Subsystem Device ID 
> matching
> +         * the Virtio Device ID"
> +         */
> +        dev->vdev.device_type = qpci_config_readw(dev->pdev, 
> PCI_SUBSYSTEM_ID);

Shouldn't you return "false" here in case the device_type is 0 ? Which
likely means that it is a legacy or broken device ...?

> +    } else {
> +        /*
> +         * "The PCI Device ID is calculated by adding 0x1040 to the Virtio
> +         * Device ID"
> +         */
> +        dev->vdev.device_type = device_id - 0x1040;
> +    }
> +
> +    return true;
> +}

 Thomas