Single EFI fix for v5.9-rc:

- ensure that the EFI bootloader control module only probes successfully
   on systems that support the EFI SetVariable runtime service
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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

@@ -84,7 +84,7 @@ static int __init efibc_init(void)
 {
 	int ret;
 
-	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+	if (!efivars_kobject() || !efivar_supports_writes())
 		return -ENODEV;
 
 	ret = register_reboot_notifier(&efibc_reboot_notifier);