efi: Update efi_mem_type() to return an error rather than 0

The efi_mem_type() function currently returns a 0, which maps to
EFI_RESERVED_TYPE, if the function is unable to find a memmap entry for
the supplied physical address. Returning EFI_RESERVED_TYPE implies that
a memmap entry exists, when it doesn't.  Instead of returning 0, change
the function to return a negative error value when no memmap entry is
found.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/7fbf40a9dc414d5da849e1ddcd7f7c1285e4e181.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/ia64/kernel/efi.c

@@ -757,14 +757,14 @@ efi_memmap_intersects (unsigned long phys_addr, unsigned long size)
 	return 0;
 }
 
-u32
+int
 efi_mem_type (unsigned long phys_addr)
 {
 	efi_memory_desc_t *md = efi_memory_descriptor(phys_addr);
 
 	if (md)
 		return md->type;
-	return 0;
+	return -EINVAL;
 }
 
 u64

arch/x86/platform/efi/efi.c

@@ -1035,12 +1035,12 @@ void __init efi_enter_virtual_mode(void)
 /*
  * Convenience functions to obtain memory types and attributes
  */
-u32 efi_mem_type(unsigned long phys_addr)
+int efi_mem_type(unsigned long phys_addr)
 {
 	efi_memory_desc_t *md;
 
 	if (!efi_enabled(EFI_MEMMAP))
-		return 0;
+		return -ENOTSUPP;
 
 	for_each_efi_memory_desc(md) {
 		if ((md->phys_addr <= phys_addr) &&
@@ -1048,7 +1048,7 @@ u32 efi_mem_type(unsigned long phys_addr)
 				  (md->num_pages << EFI_PAGE_SHIFT))))
 			return md->type;
 	}
-	return 0;
+	return -EINVAL;
 }
 
 static int __init arch_parse_efi_cmdline(char *str)

include/linux/efi.h

@@ -985,7 +985,7 @@ static inline void efi_esrt_init(void) { }
 extern int efi_config_parse_tables(void *config_tables, int count, int sz,
 				   efi_config_table_type_t *arch_tables);
 extern u64 efi_get_iobase (void);
-extern u32 efi_mem_type (unsigned long phys_addr);
+extern int efi_mem_type(unsigned long phys_addr);
 extern u64 efi_mem_attributes (unsigned long phys_addr);
 extern u64 efi_mem_attribute (unsigned long phys_addr, unsigned long size);
 extern int __init efi_uart_console_only (void);