6.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Suzuki K Poulose suzuki.poulose@arm.com
[ Upstream commit 7d953a06241624ee2efb172d037a4168978f4147 ]
When a device performs DMA to a shared buffer using physical addresses, (without Stage1 translation), the device must use the "{I}PA address" with the top bit set in Realm. This is to make sure that a trusted device will be able to write to shared buffers as well as the protected buffers. Thus, a Realm must always program the full address including the "protection" bit, like AMD SME encryption bits.
Enable this by providing arm64 specific dma_addr_{encrypted, canonical} helpers for Realms. Please note that the VMM needs to similarly make sure that the SMMU Stage2 in the Non-secure world is setup accordingly to map IPA at the unprotected alias.
Cc: Will Deacon will@kernel.org Cc: Jean-Philippe Brucker jean-philippe@linaro.org Cc: Robin Murphy robin.murphy@arm.com Cc: Steven Price steven.price@arm.com Cc: Christoph Hellwig hch@lst.de Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Aneesh Kumar K.V aneesh.kumar@kernel.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com Reviewed-by: Gavin Shan gshan@redhat.com Acked-by: Catalin Marinas catalin.marinas@arm.com Reviewed-by: Robin Murphy robin.murphy@arm.com Acked-by: Marek Szyprowski m.szyprowski@samsung.com Fixes: 42be24a4178f ("arm64: Enable memory encrypt for Realms") Acked-by: Will Deacon will@kernel.org Link: https://lore.kernel.org/r/20250227144150.1667735-4-suzuki.poulose@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/include/asm/mem_encrypt.h | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/arch/arm64/include/asm/mem_encrypt.h b/arch/arm64/include/asm/mem_encrypt.h index f8f78f622dd2c..a2a1eeb36d4b5 100644 --- a/arch/arm64/include/asm/mem_encrypt.h +++ b/arch/arm64/include/asm/mem_encrypt.h @@ -21,4 +21,15 @@ static inline bool force_dma_unencrypted(struct device *dev) return is_realm_world(); }
+/* + * For Arm CCA guests, canonical addresses are "encrypted", so no changes + * required for dma_addr_encrypted(). + * The unencrypted DMA buffers must be accessed via the unprotected IPA, + * "top IPA bit" set. + */ +#define dma_addr_unencrypted(x) ((x) | PROT_NS_SHARED) + +/* Clear the "top" IPA bit while converting back */ +#define dma_addr_canonical(x) ((x) & ~PROT_NS_SHARED) + #endif /* __ASM_MEM_ENCRYPT_H */