[PATCH, RFC 52/62] x86/mm: introduce common code for mem encryption

[Kirill A. Shutemov]

From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>

Both Intel MKTME and AMD SME have needs to support DMA address
translation with encryption related bits. Common functions are
introduced in this patch to keep DMA generic code abstracted.

Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/Kconfig                 |  4 ++++
 arch/x86/mm/Makefile             |  1 +
 arch/x86/mm/mem_encrypt_common.c | 28 ++++++++++++++++++++++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 arch/x86/mm/mem_encrypt_common.c

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 62cfb381fee3..ce9642e2c31b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1505,11 +1505,15 @@ config X86_CPA_STATISTICS
 config ARCH_HAS_MEM_ENCRYPT
 	def_bool y
 
+config X86_MEM_ENCRYPT_COMMON
+	def_bool n
+
 config AMD_MEM_ENCRYPT
 	bool "AMD Secure Memory Encryption (SME) support"
 	depends on X86_64 && CPU_SUP_AMD
 	select DYNAMIC_PHYSICAL_MASK
 	select ARCH_USE_MEMREMAP_PROT
+	select X86_MEM_ENCRYPT_COMMON
 	---help---
 	  Say yes to enable support for the encryption of system memory.
 	  This requires an AMD processor that supports Secure Memory
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 4ebee899c363..89dddbc01b1b 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_identity.o
 obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_boot.o
 
 obj-$(CONFIG_X86_INTEL_MKTME)	+= mktme.o
+obj-$(CONFIG_X86_MEM_ENCRYPT_COMMON)	+= mem_encrypt_common.o
diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c
new file mode 100644
index 000000000000..2adee65eec46
--- /dev/null
+++ b/arch/x86/mm/mem_encrypt_common.c
@@ -0,0 +1,28 @@
+#include <linux/mm.h>
+#include <linux/mem_encrypt.h>
+#include <asm/mktme.h>
+
+/*
+ * Encryption bits need to be set and cleared for both Intel MKTME and
+ * AMD SME when converting between DMA address and physical address.
+ */
+dma_addr_t __mem_encrypt_dma_set(dma_addr_t daddr, phys_addr_t paddr)
+{
+	unsigned long keyid;
+
+	if (sme_active())
+		return __sme_set(daddr);
+	keyid = page_keyid(pfn_to_page(__phys_to_pfn(paddr)));
+
+	return (daddr & ~mktme_keyid_mask) | (keyid << mktme_keyid_shift);
+}
+EXPORT_SYMBOL_GPL(__mem_encrypt_dma_set);
+
+phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr)
+{
+	if (sme_active())
+		return __sme_clr(paddr);
+
+	return paddr & ~mktme_keyid_mask;
+}
+EXPORT_SYMBOL_GPL(__mem_encrypt_dma_clear);
-- 
2.20.1