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

[Thomas Huth <thuth@redhat.com>]

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On 17/10/2019 18.07, Stefan Hajnoczi wrote:
> On Thu, Oct 17, 2019 at 04:52:54PM +0200, Thomas Huth wrote:
>> 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 <stefanha@redhat.com>
>>> ---
>>>  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 ...?
> 
> The real decision whether to use this PCI device or not happens in
> probe_device_layout().  If it's broken or a legacy device then that
> function will fail.

Ok, fair.

I've added the patches to my qtest-next branch:

https://gitlab.com/huth/qemu/tree/qtest-next

 Thomas




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