Commit 163f9fe6 authored by Breno Leitao's avatar Breno Leitao Committed by Borislav Petkov (AMD)
Browse files

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



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: 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/20240729164105.554296-4-leitao@debian.org
parent b8da0b33

arch/x86/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/cpu/bugs.c

+2 −1
Original line number Diff line number Diff line
@@ -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[] = {