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x86/bugs: Add a separate config for SRBDS

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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 SRBDS 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/20240729164105.554296-8-leitao@debian.org
This commit is contained in:
Breno Leitao 2024-07-29 09:40:55 -07:00 committed by Borislav Petkov (AMD)
parent ca01c0d8d0
commit a0b02e3fe3
2 changed files with 16 additions and 1 deletions
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14
arch/x86/Kconfig
View File

@ -2715,6 +2715,20 @@ config MITIGATION_SPECTRE_V1
execution that bypasses conditional branch instructions used for
memory access bounds check.
See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
config MITIGATION_SRBDS
bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
depends on CPU_SUP_INTEL
default y
help
Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
SRBDS is a hardware vulnerability that allows Microarchitectural Data
Sampling (MDS) techniques to infer values returned from special
register accesses. An unprivileged user can extract values returned
from RDRAND and RDSEED executed on another core or sibling thread
using MDS techniques.
See also
<file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
endif
config ARCH_HAS_ADD_PAGES

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

@ -608,7 +608,8 @@ enum srbds_mitigations {
SRBDS_MITIGATION_HYPERVISOR,
};
static enum srbds_mitigations srbds_mitigation __ro_after_init = SRBDS_MITIGATION_FULL;
static enum srbds_mitigations srbds_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_SRBDS) ? SRBDS_MITIGATION_FULL : SRBDS_MITIGATION_OFF;
static const char * const srbds_strings[] = {
[SRBDS_MITIGATION_OFF] = "Vulnerable",