[RFC 01/16] x86/mm: Move force_dma_unencrypted() to common code

[Kirill A. Shutemov]

force_dma_unencrypted() has to return true for KVM guest with the memory
protected enabled. Move it out of AMD SME code.

Introduce new config option X86_MEM_ENCRYPT_COMMON that has to be
selected by all x86 memory encryption features.

This is preparation for the following patches.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/Kconfig                 |  8 +++++--
 arch/x86/include/asm/io.h        |  4 +++-
 arch/x86/mm/Makefile             |  2 ++
 arch/x86/mm/mem_encrypt.c        | 30 -------------------------
 arch/x86/mm/mem_encrypt_common.c | 38 ++++++++++++++++++++++++++++++++
 5 files changed, 49 insertions(+), 33 deletions(-)
 create mode 100644 arch/x86/mm/mem_encrypt_common.c

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2d3f963fd6f1..bc72bfd89bcf 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1518,12 +1518,16 @@ config X86_CPA_STATISTICS
 	  helps to determine the effectiveness of preserving large and huge
 	  page mappings when mapping protections are changed.
 
+config X86_MEM_ENCRYPT_COMMON
+	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
+	select DYNAMIC_PHYSICAL_MASK
+	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 ARCH_HAS_FORCE_DMA_UNENCRYPTED
+	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/include/asm/io.h b/arch/x86/include/asm/io.h
index e1aa17a468a8..c58d52fd7bf2 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -256,10 +256,12 @@ static inline void slow_down_io(void)
 
 #endif
 
-#ifdef CONFIG_AMD_MEM_ENCRYPT
 #include <linux/jump_label.h>
 
 extern struct static_key_false sev_enable_key;
+
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+
 static inline bool sev_key_active(void)
 {
 	return static_branch_unlikely(&sev_enable_key);
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index 98f7c6fa2eaa..af8683c053a3 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -49,6 +49,8 @@ obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS)	+= pkeys.o
 obj-$(CONFIG_RANDOMIZE_MEMORY)			+= kaslr.o
 obj-$(CONFIG_PAGE_TABLE_ISOLATION)		+= pti.o
 
+obj-$(CONFIG_X86_MEM_ENCRYPT_COMMON)	+= mem_encrypt_common.o
+
 obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt.o
 obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_identity.o
 obj-$(CONFIG_AMD_MEM_ENCRYPT)	+= mem_encrypt_boot.o
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index a03614bd3e1a..112304a706f3 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -15,10 +15,6 @@
 #include <linux/dma-direct.h>
 #include <linux/swiotlb.h>
 #include <linux/mem_encrypt.h>
-#include <linux/device.h>
-#include <linux/kernel.h>
-#include <linux/bitops.h>
-#include <linux/dma-mapping.h>
 
 #include <asm/tlbflush.h>
 #include <asm/fixmap.h>
@@ -350,32 +346,6 @@ bool sev_active(void)
 	return sme_me_mask && sev_enabled;
 }
 
-/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
-bool force_dma_unencrypted(struct device *dev)
-{
-	/*
-	 * For SEV, all DMA must be to unencrypted addresses.
-	 */
-	if (sev_active())
-		return true;
-
-	/*
-	 * For SME, all DMA must be to unencrypted addresses if the
-	 * device does not support DMA to addresses that include the
-	 * encryption mask.
-	 */
-	if (sme_active()) {
-		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);
-
-		if (dma_dev_mask <= dma_enc_mask)
-			return true;
-	}
-
-	return false;
-}
-
 /* Architecture __weak replacement functions */
 void __init mem_encrypt_free_decrypted_mem(void)
 {
diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c
new file mode 100644
index 000000000000..964e04152417
--- /dev/null
+++ b/arch/x86/mm/mem_encrypt_common.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Memory Encryption Support
+ *
+ * Copyright (C) 2016 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@xxxxxxx>
+ */
+
+#include <linux/mm.h>
+#include <linux/mem_encrypt.h>
+#include <linux/dma-mapping.h>
+
+/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
+bool force_dma_unencrypted(struct device *dev)
+{
+	/*
+	 * For SEV, all DMA must be to unencrypted/shared addresses.
+	 */
+	if (sev_active())
+		return true;
+
+	/*
+	 * For SME, all DMA must be to unencrypted addresses if the
+	 * device does not support DMA to addresses that include the
+	 * encryption mask.
+	 */
+	if (sme_active()) {
+		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);
+
+		if (dma_dev_mask <= dma_enc_mask)
+			return true;
+	}
+
+	return false;
+}
-- 
2.26.2