efi: fix userspace infinite retry read efivars after EFI runtime serv…

…ices page fault

commit e006ac3 upstream.

After [1][2], if we catch exceptions due to EFI runtime service, we will
clear EFI_RUNTIME_SERVICES bit to disable EFI runtime service, then the
subsequent routine which invoke the EFI runtime service should fail.

But the userspace cat efivars through /sys/firmware/efi/efivars/ will stuck
and infinite loop calling read() due to efivarfs_file_read() return -EINTR.

The -EINTR is converted from EFI_ABORTED by efi_status_to_err(), and is
an improper return value in this situation, so let virt_efi_xxx() return
EFI_DEVICE_ERROR and converted to -EIO to invoker.

Cc: <stable@vger.kernel.org>
Fixes: 3425d93 ("efi/x86: Handle page faults occurring while running EFI runtime services")
Fixes: 23715a2 ("arm64: efi: Recover from synchronous exceptions occurring in firmware")
Signed-off-by: Ding Hui <dinghui@sangfor.com.cn>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/firmware/efi/runtime-wrappers.c

@@ -62,6 +62,7 @@ struct efi_runtime_work efi_rts_work;
 									\
 	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {			\
 		pr_warn_once("EFI Runtime Services are disabled!\n");	\
+		efi_rts_work.status = EFI_DEVICE_ERROR;			\
 		goto exit;						\
 	}								\
 									\