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@oracle.com>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tom Lendacky <Thomas.Lendacky@amd.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas <Thomas.Lendacky@amd.com>
Fixes: 21729f81ce ("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@kernel.org>

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 */