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x86/bugs: Add a separate config for MDS

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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 MDS CPU mitigation under
CONFIG_SPECULATION_MITIGATIONS. This allow users to enable or disable
it at compilation time.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240729164105.554296-2-leitao@debian.org
This commit is contained in:
Breno Leitao
2024-07-29 09:40:49 -07:00
committed by Borislav Petkov (AMD)
parent 8400291e28
commit 940455681d
2 changed files with 11 additions and 1 deletions
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9
arch/x86/Kconfig
View File

@@ -2650,6 +2650,15 @@ config MITIGATION_SPECTRE_BHI
indirect branches.
See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
config MITIGATION_MDS
bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
depends on CPU_SUP_INTEL
default y
help
Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
a hardware vulnerability which allows unprivileged speculative access
to data which is available in various CPU internal buffers.
See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
endif
config ARCH_HAS_ADD_PAGES

3
arch/x86/kernel/cpu/bugs.c
View File

@@ -233,7 +233,8 @@ static void x86_amd_ssb_disable(void)
#define pr_fmt(fmt) "MDS: " fmt
/* Default mitigation for MDS-affected CPUs */
static enum mds_mitigations mds_mitigation __ro_after_init = MDS_MITIGATION_FULL;
static enum mds_mitigations mds_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_MDS) ? MDS_MITIGATION_FULL : MDS_MITIGATION_OFF;
static bool mds_nosmt __ro_after_init = false;
static const char * const mds_strings[] = {