"dma-mapping: remove CONFIG_DMA_REMAP" causes AMD SME boot fail

[Alex Xu (Hello71)]

Hi,

After a recent kernel update, booting one of my machines causes it to 
hang on a black screen. Pressing Lock keys on the USB keyboard does not 
turn on the indicators, and the machine does not appear on the Ethernet 
network. I don't have a serial port on this machine. I didn't try 
netconsole, but I suspect it won't work.

Setting mem_encrypt=0 seems to resolve the issue. Reverting f5ff79fddf0e 
("dma-mapping: remove CONFIG_DMA_REMAP") also appears to resolve the 
issue.

The machine in question has an AMD Ryzen 5 1600 and ASRock B450 Pro4.

Cheers,
Alex.