Hiding usb controllers from dom0

I was following these instructions:

But the section for EFI is blank for me, there is nothing in /boot/efi/EFI/qubes/xen.cfg in dom0.

Is that normal?

For the GRUB2 instructions, it says there should just be one line that begins with GRUB_CMDLINE_LINUX in /etc/default/grub, but I have two different lines.

The first line already has something after the = sign, something to do with luks.

The second one is: GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX and I added a space and rd.qubes.hide_all_usb, followed by running the command grub2-mkconfig -o /boot/grub2/grub.cfg as instructed.

Am I doing that correctly?

Is there a way to hide usb controllers from the bios, or only dom0?