[dpdk-dev] [PATCH 2/2] igb_uio: fix interrupt enablement after FLR in VM

Ferruh Yigit ferruh.yigit at intel.com
Fri Oct 13 22:54:57 CEST 2017


On 10/9/2017 9:31 PM, Jingjing Wu wrote:
> If pass-through a VF by vfio-pci to a Qemu VM, after FLR
> in VM, the interrupt setting is not recoverd correctly
> to host as below:
>  in VM guest:
>         Capabilities: [70] MSI-X: Enable+ Count=5 Masked-
>  in Host:
>         Capabilities: [70] MSI-X: Enable+ Count=5 Masked-
> 
> That was because in pci_reset_function, it first reads the
> PCI configure and set FLR reset, and then writes PCI configure
> as restoration. But not all the writing are successful to Host.
> Becuase vfio-pci driver doesn't allow directly write PCI MSI-X
> Cap.
> 
> To fix this issue, we need to move the interrupt enablement from
> igb_uio probe to open device file. While is also the similar as
> the behaviour in vfio_pci kernel module code.

So I guess this also explains why pci_reset in open() cause the problem,
when this is called for VF, interrupts stays disable for both VF and PF?

> 
> Fixes: b58eedfc7dd5 ("igb_uio: issue FLR during open and release of device file")
> 
> Cc: stable at dpdk.org
> 
> Signed-off-by: Jingjing Wu <jingjing.wu at intel.com>
> Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>

Acked-by: Ferruh Yigit <ferruh.yigit at intel.com>


We have two options, getting this patch or revert the original patch,
Thomas already has a patch for reverting.

The original patch is to make igb_uio safer. To not leave device in
unwanted stated. Problem related to this has been reported a few times,
I believe it is good to fix this problem. And since we already have some
movement towards fix, I say lets continue instead of revert.

Only problem is the scope of the patch is wide, and in previous release
it already break some uses cases, this is a little scary, please support
on testing this more.

I suggest getting this fix for rc1 and let it to be tested properly, and
if we hit some problem, we can always revert and work on problem for
next release.

Thanks,
ferruh


More information about the dev mailing list