acpi, x86/mm: Remove encryption mask from ACPI page protection type

The arch_apei_get_mem_attributes() function is used to set the page
protection type for ACPI physical addresses. When SME is active, the
associated protection type cannot have the encryption mask set since the
ACPI tables live in un-encrypted memory - the kernel will see corrupted
data.

To fix this, create a new protection type, PAGE_KERNEL_NOENC, that is a
'no encryption' version of PAGE_KERNEL, and return that from
arch_apei_get_mem_attributes().

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/e1cb9395b2f061cd96f1e59c3cbbe5ff5d4ec26e.1501186516.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/acpi.h

@@ -160,12 +160,13 @@ static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
 	 * you call efi_mem_attributes() during boot and at runtime,
 	 * you could theoretically see different attributes.
 	 *
-	 * Since we are yet to see any x86 platforms that require
-	 * anything other than PAGE_KERNEL (some arm64 platforms
-	 * require the equivalent of PAGE_KERNEL_NOCACHE), return that
-	 * until we know differently.
+	 * We are yet to see any x86 platforms that require anything
+	 * other than PAGE_KERNEL (some ARM64 platforms require the
+	 * equivalent of PAGE_KERNEL_NOCACHE). Additionally, if SME
+	 * is active, the ACPI information will not be encrypted,
+	 * so return PAGE_KERNEL_NOENC until we know differently.
 	 */
-	 return PAGE_KERNEL;
+	return PAGE_KERNEL_NOENC;
 }
 #endif
 

arch/x86/include/asm/pgtable_types.h

@@ -211,6 +211,7 @@ enum page_cache_mode {
 #define __PAGE_KERNEL_NOENC_WP	(__PAGE_KERNEL_WP)
 
 #define PAGE_KERNEL		__pgprot(__PAGE_KERNEL | _PAGE_ENC)
+#define PAGE_KERNEL_NOENC	__pgprot(__PAGE_KERNEL)
 #define PAGE_KERNEL_RO		__pgprot(__PAGE_KERNEL_RO | _PAGE_ENC)
 #define PAGE_KERNEL_EXEC	__pgprot(__PAGE_KERNEL_EXEC | _PAGE_ENC)
 #define PAGE_KERNEL_EXEC_NOENC	__pgprot(__PAGE_KERNEL_EXEC)