Questions about the VFIO BAR region

[Li Qiang]

Hello Alex, Auger and all,

 

I have a question about the VFIO virtual device BAR.

 

In vfio_region_setup, it initialize a ‘region->mem’ MR and set its ops to ‘vfio_regions_ops’.

In ‘vfio_region_mmap’, it maps the physical device’s MMIO to QEMU’s virtual address space

as a raw MR ‘region->mmaps[i].mem’.

And also it set the latter MR as a subregion of the first one.

 

So when the guest accesses the BAR, it will direct go to the physical device’s BAR.

My question is here:

When the qemu will use the ‘vfio_regions_ops’ to read/write the BAR?

Also whey in the last of ‘vfio_region_write/read’ we need to call ‘vbasedev->ops->vfio_eoi(vbasedev);’?

 

 

Thanks,

Li Qiang