linux-kernel - [PATCH, RFC 53/62] x86/mm: Use common code for DMA memory encryption

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Date:   Wed,  8 May 2019 17:44:13 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        David Howells <dhowells@...hat.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Alison Schofield <alison.schofield@...el.com>,
        linux-mm@...ck.org, kvm@...r.kernel.org, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH, RFC 53/62] x86/mm: Use common code for DMA memory encryption

From: Jacob Pan <jacob.jun.pan@...ux.intel.com>

Replace sme_ code with x86 memory encryption common code such that
Intel MKTME can be supported underneath generic DMA code.
dma_to_phys() & phys_to_dma() results will be runtime modified by
memory encryption code.

Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 arch/x86/include/asm/mem_encrypt.h | 29 +++++++++++++++++++++++++++++
 arch/x86/mm/mem_encrypt_common.c   |  2 +-
 include/linux/dma-direct.h         |  4 ++--
 include/linux/mem_encrypt.h        | 23 ++++++++++-------------
 4 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 616f8e637bc3..a2b69cbb0e41 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -55,8 +55,19 @@ bool sev_active(void);
 
 #define __bss_decrypted __attribute__((__section__(".bss..decrypted")))
 
+/*
+ * The __sme_set() and __sme_clr() macros are useful for adding or removing
+ * the encryption mask from a value (e.g. when dealing with pagetable
+ * entries).
+ */
+#define __sme_set(x)		((x) | sme_me_mask)
+#define __sme_clr(x)		((x) & ~sme_me_mask)
+
 #else	/* !CONFIG_AMD_MEM_ENCRYPT */
 
+#define __sme_set(x)		(x)
+#define __sme_clr(x)		(x)
+
 #define sme_me_mask	0ULL
 
 static inline void __init sme_early_encrypt(resource_size_t paddr,
@@ -97,4 +108,22 @@ extern char __start_bss_decrypted[], __end_bss_decrypted[], __start_bss_decrypte
 
 #endif	/* __ASSEMBLY__ */
 
+#ifdef CONFIG_X86_MEM_ENCRYPT_COMMON
+
+extern dma_addr_t __mem_encrypt_dma_set(dma_addr_t daddr, phys_addr_t paddr);
+extern phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr);
+
+#else
+static inline dma_addr_t __mem_encrypt_dma_set(dma_addr_t daddr, phys_addr_t paddr)
+{
+	return daddr;
+}
+
+static inline phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr)
+{
+	return paddr;
+}
+#endif /* CONFIG_X86_MEM_ENCRYPT_COMMON */
+
+
 #endif	/* __X86_MEM_ENCRYPT_H__ */
diff --git a/arch/x86/mm/mem_encrypt_common.c b/arch/x86/mm/mem_encrypt_common.c
index 2adee65eec46..dcc5c710a235 100644
--- a/arch/x86/mm/mem_encrypt_common.c
+++ b/arch/x86/mm/mem_encrypt_common.c
@@ -1,5 +1,5 @@
 #include <linux/mm.h>
-#include <linux/mem_encrypt.h>
+#include <asm/mem_encrypt.h>
 #include <asm/mktme.h>
 
 /*
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index b7338702592a..a949adeb6558 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -40,12 +40,12 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
  */
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
-	return __sme_set(__phys_to_dma(dev, paddr));
+	return __mem_encrypt_dma_set(__phys_to_dma(dev, paddr), paddr);
 }
 
 static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 {
-	return __sme_clr(__dma_to_phys(dev, daddr));
+	return __mem_encrypt_dma_clear(__dma_to_phys(dev, daddr));
 }
 
 u64 dma_direct_get_required_mask(struct device *dev);
diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h
index b310a9c18113..ce8ff0ead16c 100644
--- a/include/linux/mem_encrypt.h
+++ b/include/linux/mem_encrypt.h
@@ -26,6 +26,16 @@
 static inline bool sme_active(void) { return false; }
 static inline bool sev_active(void) { return false; }
 
+static inline dma_addr_t __mem_encrypt_dma_set(dma_addr_t daddr, phys_addr_t paddr)
+{
+	return daddr;
+}
+
+static inline phys_addr_t __mem_encrypt_dma_clear(phys_addr_t paddr)
+{
+	return paddr;
+}
+
 #endif	/* CONFIG_ARCH_HAS_MEM_ENCRYPT */
 
 static inline bool mem_encrypt_active(void)
@@ -38,19 +48,6 @@ static inline u64 sme_get_me_mask(void)
 	return sme_me_mask;
 }
 
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-/*
- * The __sme_set() and __sme_clr() macros are useful for adding or removing
- * the encryption mask from a value (e.g. when dealing with pagetable
- * entries).
- */
-#define __sme_set(x)		((x) | sme_me_mask)
-#define __sme_clr(x)		((x) & ~sme_me_mask)
-#else
-#define __sme_set(x)		(x)
-#define __sme_clr(x)		(x)
-#endif
-
 #endif	/* __ASSEMBLY__ */
 
 #endif	/* __MEM_ENCRYPT_H__ */
-- 
2.20.1