Re: [dpdk-dev] [PATCH v5 3/3] PCI: don't use vfio ioctl call to access PIO resource

["谢华伟(此时此刻）" <huawei.xhw@alibaba-inc.com>]

On 2021/1/26 20:35, Maxime Coquelin wrote:
>
> On 1/26/21 1:30 PM, 谢华伟(此时此刻） wrote:
>> On 2021/1/22 15:25, chris wrote:
>>> On 2021/1/21 23:38, Maxime Coquelin wrote:
>>>>> Do you mean we apply or abandon patch 3? I am both OK. The first
>>>>> priority to me is to enable MMIO bar support.
>>>> OK, so yes, I think we should abandon patch 2 and patch 3.
>>>> For patch 1, it looks valid to me, but I'll let Ferruh decide.
>>>>
>>>> For your device, if my understanding is correct, what we need to do is
>>>> to support MMIO for legacy devices. Correct?
>>> yes.
>>>> If so, the change should be in virtio_pci.c. In vtpci_init(), after
>>>> modern detection has failed, we should check the the BAR is PIO or MMIO
>>>> based on the flag. the result can be saved in struct virtio_pci_dev.
>>>>
>>>>
>>>> We would introduce new wrappers like vtpci_legacy_read,
>>>> vtpci_legacy_write that would either call rte_pci_ioport_read,
>>>> rte_pci_ioport_read in case of PIO, or rte_read32, rte_write32 in case
>>>> of MMIO.
>>> There are two choices.
>>>
>>> 1, apply patch 2.
>>>
>>>      IO/MMIO port are mapped and accessed using the same API. Kernel is
>>> doing in the same way like the following.
>>>
>>>              io_addr = pci_iomap
>>>
>>>                  get PIO directly or ioremap
>>>
>>>              iowrite16/32(val, io_addr + offset)
>>>
>>> I think applying patch 2 is a correct choice. It is a fix. Driver had
>>> better not know if bar is PIO or MMIO.  ioport in ioport_xx API means
>>> IO, not PIO.
>>>
>>> Btw, it only affects virtio PMD,  not that intrusive.
>>>
>>>   2, virtio specific change to enable MMIO support.
>>>
>>> Comparing with choice 1, i feels it is not that clean and pretty.
>>>
>>>> It is not too late for this release, as the change will not be that
>>>> intrusive. But if you prepare such patch, please base it on top of my
>>>> virtio rework series; To make it easier to you, I added it to the dpdk-
>>>> next-virtio tree:
>>>> https://git.dpdk.org/next/dpdk-next-virtio/log/?h=virtio_pmd_rework_v2
>>>>
>> Hi Maxime:
>>
>> Decision on patch 2?
>>
>> I still think current patch 2 is cleaner.
> Hi,
>
> I actually replied one hour ago:
> "
> OK, that makes sense. I am OK with keeping patch 2, but would like
> Ferruh's ACK.
>
> Could you please post v6?
> "
Sorry, missed it. would do it.
>
> Thanks,
> Maxime
>
>
>> Thanks,  huawei
>>
>>
>>>> Maxime
>>>>