linux-kernel - [patch for-5.8 2/4] dma-direct: re-encrypt memory if dma_direct_alloc

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Message-ID: <alpine.DEB.2.22.394.2006111219200.153880@chino.kir.corp.google.com>
Date:   Thu, 11 Jun 2020 12:20:29 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Christoph Hellwig <hch@....de>
cc:     Thomas Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [patch for-5.8 2/4] dma-direct: re-encrypt memory if dma_direct_alloc_pages()
 fails

If arch_dma_set_uncached() fails after memory has been decrypted, it needs
to be re-encrypted before freeing.

Fixes: fa7e2247c572 ("dma-direct: make uncached_kernel_address more
general")
Cc: stable@...r.kernel.org # 5.7
Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 kernel/dma/direct.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -220,7 +220,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
 		arch_dma_prep_coherent(page, size);
 		ret = arch_dma_set_uncached(ret, size);
 		if (IS_ERR(ret))
-			goto out_free_pages;
+			goto out_encrypt_pages;
 	}
 done:
 	if (force_dma_unencrypted(dev))
@@ -228,6 +228,10 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
 	else
 		*dma_handle = phys_to_dma(dev, page_to_phys(page));
 	return ret;
+out_encrypt_pages:
+	if (force_dma_unencrypted(dev))
+		set_memory_encrypted((unsigned long)page_address(page),
+				     1 << get_order(size));
 out_free_pages:
 	dma_free_contiguous(dev, page, size);
 	return NULL;