Commit ca01c0d8 authored by Breno Leitao's avatar Breno Leitao Committed by Borislav Petkov (AMD)
Browse files

x86/bugs: Add a separate config for Spectre v1 



Currently, the CONFIG_SPECULATION_MITIGATIONS is halfway populated,
where some mitigations have entries in Kconfig, and they could be
modified, while others mitigations do not have Kconfig entries, and
could not be controlled at build time.

Create an entry for the Spectre v1 CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-7-leitao@debian.org
parent 894e2885

arch/x86/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -2705,6 +2705,16 @@ config MITIGATION_RETBLEED 
	  unprivileged attacker can use these flaws to bypass conventional

	  memory security restrictions to gain read access to privileged memory

	  that would otherwise be inaccessible.



config MITIGATION_SPECTRE_V1

	bool "Mitigate SPECTRE V1 hardware bug"

	default y

	help

	  Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a

	  class of side channel attacks that takes advantage of speculative

	  execution that bypasses conditional branch instructions used for

	  memory access bounds check.

	  See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>

endif



config ARCH_HAS_ADD_PAGES

arch/x86/kernel/cpu/bugs.c

+2 −1
Original line number Diff line number Diff line
@@ -874,7 +874,8 @@ enum spectre_v1_mitigation { 
};



static enum spectre_v1_mitigation spectre_v1_mitigation __ro_after_init =

	SPECTRE_V1_MITIGATION_AUTO;

	IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V1) ?

		SPECTRE_V1_MITIGATION_AUTO : SPECTRE_V1_MITIGATION_NONE;



static const char * const spectre_v1_strings[] = {

	[SPECTRE_V1_MITIGATION_NONE] = "Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers",