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Date:   Wed, 30 Mar 2022 13:51:07 -0400
From:   "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Subject: "dma-mapping: remove CONFIG_DMA_REMAP" causes AMD SME boot fail
To:     Christoph Hellwig <hch@infradead.org>, regressions@lists.linux.dev
Cc:     linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org
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Hi,

After a recent kernel update, booting one of my machines causes it to=20
hang on a black screen. Pressing Lock keys on the USB keyboard does not=20
turn on the indicators, and the machine does not appear on the Ethernet=20
network. I don't have a serial port on this machine. I didn't try=20
netconsole, but I suspect it won't work.

Setting mem_encrypt=3D0 seems to resolve the issue. Reverting f5ff79fddf0e=20
("dma-mapping: remove CONFIG_DMA_REMAP") also appears to resolve the=20
issue.

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

Cheers,
Alex.