Re: [Qemu-devel] [PATCHv2] virtio-pci: add MMIO property

[Paul Brook]

> @@ -682,10 +733,18 @@ void virtio_init_pci(VirtIOPCIProxy *proxy,
> VirtIODevice *vdev) if (size & (size-1))
>          size = 1 << qemu_fls(size);
>  
> +    proxy->bar0_mask = size - 1;

You'll get better performance if you use page-sized mappings.  You're already 
creating a mapping bigger than the actual data (rounding up to power-of-two), 
so you may as well pick a value that's convenient for qemu to map into the 
address space.

Paul