Comment # 3 on bug 107898 from Felix Kühling

I'm not seeing this problem on my Raven system with 4.19-rc3+ ($ git describe
v4.19-rc3-21-g5e335542de83).

The most likely explanation is that on your system IOMMUv2 is not enabled. That
may be a BIOS setting. If your system BIOS setup doesn't allow you to enable
the IOMMUv2, then you may be out of luck. I'll attach a patch that adds some
extra error messages that should confirm that or point to a different source of
the problem.