linux-kernel - Re: "dma-mapping: remove CONFIG_DMA

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Date:   Wed, 30 Mar 2022 11:01:25 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     "Alex Xu (Hello71)" <alex_y_xu@...oo.ca>
Cc:     Christoph Hellwig <hch@...radead.org>, regressions@...ts.linux.dev,
        linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Subject: Re: "dma-mapping: remove CONFIG_DMA_REMAP" causes AMD SME boot fail

Can you try this patch, which is a bit of a hack?

diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 50d209939c66c..61997c2ee0a17 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -28,7 +28,8 @@ bool force_dma_unencrypted(struct device *dev)
 	 * device does not support DMA to addresses that include the
 	 * encryption mask.
 	 */
-	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
+	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT) &&
+	    !get_dma_ops(dev)) {
 		u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
 		u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
 						dev->bus_dma_limit);