This can not be fixed on the QEMU side. If you want to have virtio-input support in seabios or grub for example, you've got to ask the seabios or grub project to add it.
** Changed in: qemu Status: New => Invalid -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1618265 Title: Loading virtio-input-host-pci drivers before boot? To allow using passthrough devices in grub and other preboot menus? Status in QEMU: Invalid Bug description: Currently virtio-input devices cannot be used before the kernel loads. This is not really a full bug but it would be much more useful if you can use the keyboard+mouse this way. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1618265/+subscriptions