linux-kernel - [PATCH] x86/reboot: Avoid EFI reboot when not running on EFI

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Date:   Thu, 29 Aug 2019 11:11:18 +0100
From:   Rob Bradford <robert.bradford@...el.com>
To:     x86@...nel.org
Cc:     Rob Bradford <robert.bradford@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, Rik van Riel <riel@...riel.com>,
        Juergen Gross <jgross@...e.com>,
        Jian-Hong Pan <jian-hong@...lessm.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86/reboot: Avoid EFI reboot when not running on EFI

Replace the check using efi_runtime_disabled() which only checks if EFI
runtime was disabled on the kernel command line with a call to
efi_enabled(EFI_RUNTIME_SERVICES) to check if EFI runtime services are
available.

In the situation where the kernel was booted without an EFI environment
then only efi_enabled(EFI_RUNTIME_SERVICES) correctly represents that no
EFI is available. Setting "noefi" or "efi=noruntime" on the commandline
continue to have the same effect as efi_enabled(EFI_RUNTIME_SERVICES)
will return false.

Signed-off-by: Rob Bradford <robert.bradford@...el.com>
---
 arch/x86/kernel/reboot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 09d6bded3c1e..0b0a7fccdb00 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -500,7 +500,7 @@ static int __init reboot_init(void)
 	 */
 	rv = dmi_check_system(reboot_dmi_table);

-	if (!rv && efi_reboot_required() && !efi_runtime_disabled())
+	if (!rv && efi_reboot_required() && efi_enabled(EFI_RUNTIME_SERVICES))
 		reboot_type = BOOT_EFI;

 	return 0;
-- 
2.21.0