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

[Maxime Coquelin]

On 1/22/21 8:25 AM, 谢华伟(此时此刻） 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.

OK, that makes sense. I am OK with keeping patch 2, but would like
Ferruh's ACK.

Could you please post v6?

Thanks,
Maxime

>>
>> 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
>>
>> Thanks,
>> Maxime
>>
>