On 2021/1/13 1:37, Maxime Coquelin wrote:

On 10/22/20 5:51 PM, 谢华伟(此时此刻） wrote:

quoted

From: "huawei.xhw" <redacted>

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.

Regarding the performance issue, do you have some numbers to share?
AFAICS, it can only have an impact on performance when interrupt mode is
used or queue notification is enabled.

I didn't have performance number, but would do it when have time.

Yes, it is not needed when virtio backend/device is working in polling mode.

But anyway, ioctl isn't needed at all.

/huawei

Does your HW Virtio implementation requires notification?

Is performance the only issue to have your HW working with Virtio PMD,
or is this series also fixing some functionnal issues?

There is two purpose with this patch. One is to support MMIO, and the 
other is to

unify/simplify the way to get IO/MMIO resource and read/write IO/MMIO 
port for virtio PMD.

Current implementation is too complicated.

/huawei

Best regards,
Maxime

quoted

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.

v2 changes:
	 - add more explanation in the commit message

v3 changes:
	 - fix patch format issues

v4 changes:
	 - fixes for RTE_KDRV_UIO_GENERIC -> RTE_PCI_KDRV_UIO_GENERIC

v5 changes:
	 - split into three seperate patches

huawei.xhw (3):
   PCI: use PCI standard sysfs entry to get PIO address
   PCI: support MMIO in rte_pci_ioport_map/unap/read/write
   PCI: don't use vfio ioctl call to access PIO resource

  drivers/bus/pci/linux/pci.c     |  89 +-------------------
  drivers/bus/pci/linux/pci_uio.c | 177 ++++++++++++++++++++++++++++------------
  2 files changed, 128 insertions(+), 138 deletions(-)