Errors showing while booting 16.04: "AMD-Vi: Event logged [IO_PAGE_FAULT..."

While this doesn't seem to affect performance or function in any ways, I get these errors when booting 16.04, but only when I have the proprietary Nvidia drivers installed (or possibly the AMD CPU microcode proprietary driver). The error is:

AMD-Vi: Event logged [IO_PAGE_FAULT device=02:00.0 domain=0x0011...

and then continues to show some additional numbers in sequence. See image below.

How can I make these messages go away during boot?

Running Ubuntu 16.04 x64 (Kernel 4.4.0-31-generic), Unity 7.4.0 desktop environment, AMD FX-8150 8x core CPU, 32GB RAM, 2x Nvidia GTX660 graphics cards, Nvidia 361.42 proprietary diver and microcode firmware for AMD CPU's from amd64-microcode proprietary driver.

Relevant portion of lspci:

02:00.0 USB controller: VIA Technologies, Inc. VL805 USB 3.0 Host Controller (rev 01) 

1. gksudo gedit /etc/default/grub

2. edit the line that says GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" and add iommu=soft Resulting in something like

   GRUB_CMDLINE_LINUX_DEFAULT="quiet iommu=soft splash"  
   

   if you haven't changed kernel parameters previously

The order of the parameters doesn't matter, the spaces between them are however important.

3. save the file

4. Issue the command sudo update-grub

5. Reboot

Props to @Zanna who confirmed the required kernel parameter in chat.

For a complete list of kernel parameters check https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html