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x86/bugs: Add a separate config for MMIO Stable Data

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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 MMIO Stale data 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/20240729164105.554296-4-leitao@debian.org
This commit is contained in:
Breno Leitao 2024-07-29 09:40:51 -07:00 committed by Borislav Petkov (AMD)
parent b8da0b33d3
commit 163f9fe6b6
2 changed files with 14 additions and 1 deletions
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12
arch/x86/Kconfig
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@ -2670,6 +2670,18 @@ config MITIGATION_TAA
which is available in various CPU internal buffers by using
asynchronous aborts within an Intel TSX transactional region.
See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
config MITIGATION_MMIO_STALE_DATA
bool "Mitigate MMIO Stale Data hardware bug"
depends on CPU_SUP_INTEL
default y
help
Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO
Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
vulnerabilities that can expose data. The vulnerabilities require the
attacker to have access to MMIO.
See also
<file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
endif
config ARCH_HAS_ADD_PAGES

3
arch/x86/kernel/cpu/bugs.c
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@ -393,7 +393,8 @@ enum mmio_mitigations {
};
/* Default mitigation for Processor MMIO Stale Data vulnerabilities */
static enum mmio_mitigations mmio_mitigation __ro_after_init = MMIO_MITIGATION_VERW;
static enum mmio_mitigations mmio_mitigation __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_MMIO_STALE_DATA) ? MMIO_MITIGATION_VERW : MMIO_MITIGATION_OFF;
static bool mmio_nosmt __ro_after_init = false;
static const char * const mmio_strings[] = {