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: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: NBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: NTom Lendacky <Thomas.Lendacky@amd.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas <Thomas.Lendacky@amd.com>
Fixes: 21729f81 ("x86/mm: Provide general kernel support for memory encryption")
Link: http://lkml.kernel.org/r/20170907093837.76zojtkgebwtqc74@pd.tnicSigned-off-by: NIngo Molnar <mingo@kernel.org>

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) { }

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 */

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__ */