Re: [dpdk-dev] [PATCH v4] pci: support both PIO and MMIO BAR for legacy virtio on x86

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

Hi Ferruh:

Comments to this patch? Customers are urging us to run DPDK with virtio 
mmio support.

@david


Though this patch is to support MMIO bar, it is the right thing to do.

Previous code with virtio (IO/MMIO) port map/RW under different driver 
is too complicated.

This patch also fixes the performance issue with VFIO port write(virtio 
only).

Besides, next thing we could do is to move some of those PCI codes to 
virtio PMD as they are for virtio

PMD only.

/huawei


On 2020/10/13 16:41, 谢华伟(此时此刻） wrote:
> From: "huawei.xhw" <huawei.xhw@alibaba-inc.com>
>
> Legacy virtio-pci only supports PIO BAR resource. As we need to create lots of
> virtio devices and PIO resource on x86 is very limited, we expose MMIO BAR.
>
> Kernel supports both PIO  and MMIO BAR for legacy virtio-pci device. We handles
> different type of BAR in the similar way.
>
> In previous implementation, with igb_uio we get PIO address from igb_uio
> sysfs entry; with uio_pci_generic, we get PIO address from
> /proc/ioports.
> For PIO/MMIO RW, there is different path for different drivers and arch.
> For VFIO, PIO/MMIO RW is through syscall, which has big performance
> issue.
> On X86, it assumes only PIO is supported.
>
> All of the above is too much twisted.
> This patch unifies the way to get both PIO and MMIO address for different driver
> and arch, all from standard resource attr under pci sysfs.
>
> We distinguish PIO and MMIO by their address like how kernel does. It is ugly but works.
>
> Signed-off-by: huawei.xhw <huawei.xhw@alibaba-inc.com>
> ---
>   drivers/bus/pci/linux/pci.c     |  89 +--------------------
>   drivers/bus/pci/linux/pci_uio.c | 167 +++++++++++++++++++++++++++-------------
>   2 files changed, 119 insertions(+), 137 deletions(-)
>
> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> index bf27594..885e54e 100644
> --- a/drivers/bus/pci/linux/pci.c
> +++ b/drivers/bus/pci/linux/pci.c
> @@ -687,71 +687,6 @@ int rte_pci_write_config(const struct rte_pci_device *device,
>   	}
>   }
>   
>