Merge tag 'efi-urgent-for-v5.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull EFI fix from Borislav Petkov:
"Ensure that the EFI bootloader control module only probes successfully
on systems that support the EFI SetVariable runtime service"

[ Tag and commit from Ard Biesheuvel, forwarded by Borislav ]

* tag 'efi-urgent-for-v5.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
efi: efibc: check for efivars write capability

drivers/firmware/efi/efibc.c

···
 {
 	int ret;
 
-	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+	if (!efivars_kobject() || !efivar_supports_writes())
 		return -ENODEV;
 
 	ret = register_reboot_notifier(&efibc_reboot_notifier);