From 46908326c6b801201f1e46f5ed0db6e85bef74ae Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Tue, 15 Sep 2020 18:12:09 +0300
Subject: [PATCH] efi: efibc: check for efivars write capability
Git-commit: 46908326c6b801201f1e46f5ed0db6e85bef74ae
Patch-mainline: v5.9-rc6
References: git-fixes
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 <sherrellbc@gmail.com>
Link: https://lore.kernel.org/linux-efi/AE217103-C96F-4AFC-8417-83EC11962004@gmail.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 35dccc88ac0a..15a47539dc56 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);
--
2.26.2