From: Thomas Hellstrom thellstrom@vmware.com
[ Upstream commit 17c4a2ae15a7aaefe84bdb271952678c5c9cd8e1 ]
When dma_mmap_coherent() sets up a mapping to unencrypted coherent memory under SEV encryption and sometimes under SME encryption, it will actually set up an encrypted mapping rather than an unencrypted, causing devices that DMAs from that memory to read encrypted contents. Fix this.
When force_dma_unencrypted() returns true, the linear kernel map of the coherent pages have had the encryption bit explicitly cleared and the page content is unencrypted. Make sure that any additional PTEs we set up to these pages also have the encryption bit cleared by having dma_pgprot() return a protection with the encryption bit cleared in this case.
Signed-off-by: Thomas Hellstrom thellstrom@vmware.com Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Christoph Hellwig hch@lst.de Acked-by: Tom Lendacky thomas.lendacky@amd.com Link: https://lkml.kernel.org/r/20200304114527.3636-3-thomas_os@shipmail.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/dma/mapping.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index d9334f31a5afb..8682a5305cb36 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -169,6 +169,8 @@ EXPORT_SYMBOL(dma_get_sgtable_attrs); */ pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs) { + if (force_dma_unencrypted(dev)) + prot = pgprot_decrypted(prot); if (dev_is_dma_coherent(dev) || (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) && (attrs & DMA_ATTR_NON_CONSISTENT)))