quoted

"

I think that using inb/outb in the case of VFIO with IOMMU enabled won't
work without cap_sys_rawio, and using it in the case of VFIO with IOMMU
disabled just bypasses VFIO and so is not correct.

Get your concern.

PIO bar:

    HW virtio on HW machine: any vendor implements hardware virtio 
using PIO bar? I think this isn't right. And i dout if vfio doesn't 
check rawio perssion in the syscall in this case.

    Para virtio:  you have no choice to enable unsafe no-iommu mode.  
You must have RAWIO permission.

Sorry. typo.  "you have no choice but to enable unsafe no-iommu mode. "

so with PIO bar, the regression doesn't exist in real world.

Btw, our virtio device is basically MMIO bar, either in hardware 
machine or in pass-throughed virtual machine.


Do you mean we apply or abandon patch 3? I am both OK. The first 
priority to me is to enable MMIO bar support.