From 46908326c6b801201f1e46f5ed0db6e85bef74ae Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 15 Sep 2020 18:12:09 +0300 Subject: [PATCH] efi: efibc: check for efivars write capability Branden reports that commit f88814cc2578c1 ("efi/efivars: Expose RT service availability via efivars abstraction") regresses UEFI platforms that implement GetVariable but not SetVariable when booting kernels that have EFIBC (bootloader control) enabled. The reason is that EFIBC is a user of the efivars abstraction, which was updated to permit users that rely only on the read capability, but not on the write capability. EFIBC is in the latter category, so it has to check explicitly whether efivars supports writes. Fixes: f88814cc2578c1 ("efi/efivars: Expose RT service availability via efivars abstraction") Tested-by: Branden Sherrell Link: https://lore.kernel.org/linux-efi/AE217103-C96F-4AFC-8417-83EC11962004@gmail.com/ Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/efibc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/efi/efibc.c b/drivers/firmware/efi/efibc.c index 35dccc8..15a4753 100644 --- a/drivers/firmware/efi/efibc.c +++ b/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); -- 2.7.4