linux-kernel - [tip:x86/urgent] x86/mm: Make the SME mask a u64

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Date:   Thu, 7 Sep 2017 03:34:21 -0700
From:   tip-bot for Borislav Petkov <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, hpa@...or.com, bp@...e.de,
        linux-kernel@...r.kernel.org, boris.ostrovsky@...cle.com,
        brijesh.singh@....com, peterz@...radead.org, mingo@...nel.org,
        Thomas.Lendacky@....com, torvalds@...ux-foundation.org
Subject: [tip:x86/urgent] x86/mm: Make the SME mask a u64

Commit-ID:  21d9bb4a05bac50fb4f850517af4030baecd00f6
Gitweb:     http://git.kernel.org/tip/21d9bb4a05bac50fb4f850517af4030baecd00f6
Author:     Borislav Petkov <bp@...e.de>
AuthorDate: Thu, 7 Sep 2017 11:38:37 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 7 Sep 2017 11:53:11 +0200

x86/mm: Make the SME mask a u64

The SME encryption mask is for masking 64-bit pagetable entries. It
being an unsigned long works fine on X86_64 but on 32-bit builds in
truncates bits leading to Xen guests crashing very early.

And regardless, the whole SME mask handling shouldnt've leaked into
32-bit because SME is X86_64-only feature. So, first make the mask u64.
And then, add trivial 32-bit versions of the __sme_* macros so that
nothing happens there.

Reported-and-tested-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Tested-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Tom Lendacky <Thomas.Lendacky@....com>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas <Thomas.Lendacky@....com>
Fixes: 21729f81ce8a ("x86/mm: Provide general kernel support for memory encryption")
Link: http://lkml.kernel.org/r/20170907093837.76zojtkgebwtqc74@pd.tnic
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/mem_encrypt.h |  4 ++--
 arch/x86/mm/mem_encrypt.c          |  2 +-
 include/linux/mem_encrypt.h        | 13 +++++++++----
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 8e618fc..6a77c63 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -21,7 +21,7 @@
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 
-extern unsigned long sme_me_mask;
+extern u64 sme_me_mask;
 
 void sme_encrypt_execute(unsigned long encrypted_kernel_vaddr,
 			 unsigned long decrypted_kernel_vaddr,
@@ -49,7 +49,7 @@ void swiotlb_set_mem_attributes(void *vaddr, unsigned long size);
 
 #else	/* !CONFIG_AMD_MEM_ENCRYPT */
 
-#define sme_me_mask	0UL
+#define sme_me_mask	0ULL
 
 static inline void __init sme_early_encrypt(resource_size_t paddr,
 					    unsigned long size) { }
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 0fbd092..3fcc8e0 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -37,7 +37,7 @@ static char sme_cmdline_off[] __initdata = "off";
  * reside in the .data section so as not to be zeroed out when the .bss
  * section is later cleared.
  */
-unsigned long sme_me_mask __section(.data) = 0;
+u64 sme_me_mask __section(.data) = 0;
 EXPORT_SYMBOL_GPL(sme_me_mask);
 
 /* Buffer used for early in-place encryption by BSP, no locking needed */
diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h
index 1255f09..265a9cd 100644
--- a/include/linux/mem_encrypt.h
+++ b/include/linux/mem_encrypt.h
@@ -21,7 +21,7 @@
 
 #else	/* !CONFIG_ARCH_HAS_MEM_ENCRYPT */
 
-#define sme_me_mask	0UL
+#define sme_me_mask	0ULL
 
 #endif	/* CONFIG_ARCH_HAS_MEM_ENCRYPT */
 
@@ -30,18 +30,23 @@ static inline bool sme_active(void)
 	return !!sme_me_mask;
 }
 
-static inline unsigned long sme_get_me_mask(void)
+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)		((unsigned long)(x) | sme_me_mask)
-#define __sme_clr(x)		((unsigned long)(x) & ~sme_me_mask)
+#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__ */