Re: [PATCH V2 2/4] vDPA/ifcvf: enable Intel C5000X-PL virtio-net for vDPA

Zhu, Lingshan
2021-03-09T05:51:36Z

On 3/9/2021 10:42 AM, Jason Wang wrote:
>
> On 2021/3/9 10:28 上午, Zhu, Lingshan wrote:
>>
>>
>> On 3/9/2021 10:23 AM, Jason Wang wrote:
>>>
>>> On 2021/3/8 4:35 下午, Zhu Lingshan wrote:
>>>> This commit enabled Intel FPGA SmartNIC C5000X-PL virtio-net
>>>> for vDPA
>>>>
>>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>>> ---
>>>>   drivers/vdpa/ifcvf/ifcvf_base.h | 5 +++++
>>>>   drivers/vdpa/ifcvf/ifcvf_main.c | 5 +++++
>>>>   2 files changed, 10 insertions(+)
>>>>
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> index 64696d63fe07..75d9a8052039 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>>>> @@ -23,6 +23,11 @@
>>>>   #define IFCVF_SUBSYS_VENDOR_ID    0x8086
>>>>   #define IFCVF_SUBSYS_DEVICE_ID    0x001A
>>>>   +#define C5000X_PL_VENDOR_ID        0x1AF4
>>>> +#define C5000X_PL_DEVICE_ID        0x1000
>>>> +#define C5000X_PL_SUBSYS_VENDOR_ID    0x8086
>>>> +#define C5000X_PL_SUBSYS_DEVICE_ID    0x0001
>>>
>>>
>>> I just notice that the device is a transtitional one. Any reason for
>>> doing this?
>>>
>>> Note that IFCVF is a moden device anyhow (0x1041). Supporting legacy
>>> drive may bring many issues (e.g the definition is non-nomartive).
>>> One example is the support of VIRTIO_F_IOMMU_PLATFORM, legacy driver
>>> may assume the device can bypass IOMMU.
>>>
>>> Thanks
>> Hi Jason,
>>
>> This device will support virtio1.0 by default, so has
>> VIRTIO_F_IOMMU_PLATFORM by default.
>
>
> If you device want to force VIRTIO_F_IOMMU_PLATFORM you probably need
> to do what has been done by mlx5 (verify_min_features).
>
> According to the spec, if VIRTIO_F_IOMMU_PLATFORM is not mandatory,
> when it's not negotiated, device needs to disable or bypass IOMMU:
>
>
> "
>
> If this feature bit is set to 0, then the device has same access to
> memory addresses supplied to it as the driver has. In particular, the
> device will always use physical addresses matching addresses used by
> the driver (typically meaning physical addresses used by the CPU) and
> not translated further, and can access any address supplied to it by
> the driver.
>
> "
sure, I can implement code to check the feature bits.
>
>
>> Transitional device gives the software a chance to fall back to
>> virtio 0.95.
>
>
> This only applies if you want to passthrough the card to guest
> directly without the help of vDPA.
>
> If we go with vDPA, it doesn't hlep. For virtio-vdpa, we know it will
> negotiated IOMMU_PLATFORM. For vhost-vdpa, Qemu can provide a legacy
> or transitional device on top of a modern vDPA device.
>
> Thanks
For some cases, users may run quite out of date OS does not have vDPA
nor virtio 1.0 support, transitional characters give them a chance to
use the devices.

Thanks
Zhu Lingshan
>
>
>> ifcvf drives this device in virtio 1.0 mode, set features
>> VIRTIO_F_IOMMU_PLATFORM successfully.
>>
>> Thanks,
>> Zhu Lingshan
>>>
>>>
>>>> +
>>>>   #define IFCVF_SUPPORTED_FEATURES \
>>>>           ((1ULL << VIRTIO_NET_F_MAC)            | \
>>>>            (1ULL << VIRTIO_F_ANY_LAYOUT) | \
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> index e501ee07de17..26a2dab7ca66 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> @@ -484,6 +484,11 @@ static struct pci_device_id ifcvf_pci_ids[] = {
>>>>           IFCVF_DEVICE_ID,
>>>>           IFCVF_SUBSYS_VENDOR_ID,
>>>>           IFCVF_SUBSYS_DEVICE_ID) },
>>>> +    { PCI_DEVICE_SUB(C5000X_PL_VENDOR_ID,
>>>> +             C5000X_PL_DEVICE_ID,
>>>> +             C5000X_PL_SUBSYS_VENDOR_ID,
>>>> +             C5000X_PL_SUBSYS_DEVICE_ID) },
>>>> +
>>>>       { 0 },
>>>>   };
>>>>   MODULE_DEVICE_TABLE(pci, ifcvf_pci_ids);
>>>
>>
>