I've installed the hotfix for Windows, but when I run the PowerShell script to determine whether mitigation is active, the script tells me that it's not active, due to lack of hardware support. The script then goes on to give the recommendation to "Install BIOS/firmware update provided by your device OEM that enables hardware support for the branch target injection mitigation."
It's a 1-year-old ASUS laptop and I would be surprised if they even give a sane response to my question to their technical support (I doubt they will even know what I'm talking about).