[Saucy][PATCH 1/1] efivars: check for EFI_RUNTIME_SERVICES

[joseph.salisbury at canonical.com]

From: Matt Fleming <matt.fleming at intel.com>

BugLink: http://bugs.launchpad.net/bugs/1200570

The efivars code requires EFI runtime services to function, so check
that they are enabled.

This fixes a crash when booting with the "noefi" kernel parameter, and
also when mixing kernel and firmware "bitness", e.g. 32-bit kernel with
64-bit firmware.

Tested-by: Dave Young <dyoung at redhat.com>
Signed-off-by: Matt Fleming <matt.fleming at intel.com>
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>

(cherry picked from commit d320c079efd46db1be0640d00bd6723d9e738f9f)
---
 drivers/firmware/efi/efivars.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/efivars.c b/drivers/firmware/efi/efivars.c
index 8bd1bb6..8a7432a 100644
--- a/drivers/firmware/efi/efivars.c
+++ b/drivers/firmware/efi/efivars.c
@@ -583,6 +583,9 @@ int efivars_sysfs_init(void)
 	struct kobject *parent_kobj = efivars_kobject();
 	int error = 0;
 
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		return -ENODEV;
+
 	/* No efivars has been registered yet */
 	if (!parent_kobj)
 		return 0;
-- 
1.7.9.5