5.10-stable review patch. If anyone has any objections, please let me know.
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From: Sean Christopherson seanjc@google.com
commit fe42754b94a42d08cf9501790afc25c4f6a5f631 upstream.
Rename x86's to CPU_MITIGATIONS, define it in generic code, and force it on for all architectures exception x86. A recent commit to turn mitigations off by default if SPECULATION_MITIGATIONS=n kinda sorta missed that "cpu_mitigations" is completely generic, whereas SPECULATION_MITIGATIONS is x86-specific.
Rename x86's SPECULATIVE_MITIGATIONS instead of keeping both and have it select CPU_MITIGATIONS, as having two configs for the same thing is unnecessary and confusing. This will also allow x86 to use the knob to manage mitigations that aren't strictly related to speculative execution.
Use another Kconfig to communicate to common code that CPU_MITIGATIONS is already defined instead of having x86's menu depend on the common CPU_MITIGATIONS. This allows keeping a single point of contact for all of x86's mitigations, and it's not clear that other architectures *want* to allow disabling mitigations at compile-time.
Fixes: f337a6a21e2f ("x86/cpu: Actually turn off mitigations by default for SPECULATION_MITIGATIONS=n") Closes: https://lkml.kernel.org/r/20240413115324.53303a68%40canb.auug.org.au Reported-by: Stephen Rothwell sfr@canb.auug.org.au Reported-by: Michael Ellerman mpe@ellerman.id.au Reported-by: Geert Uytterhoeven geert@linux-m68k.org Signed-off-by: Sean Christopherson seanjc@google.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Acked-by: Josh Poimboeuf jpoimboe@kernel.org Acked-by: Borislav Petkov (AMD) bp@alien8.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240420000556.2645001-2-seanjc@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/Kconfig | 8 ++++++++ arch/x86/Kconfig | 11 ++++++----- kernel/cpu.c | 4 ++-- 3 files changed, 16 insertions(+), 7 deletions(-)
--- a/arch/Kconfig +++ b/arch/Kconfig @@ -9,6 +9,14 @@ # source "arch/$(SRCARCH)/Kconfig"
+config ARCH_CONFIGURES_CPU_MITIGATIONS + bool + +if !ARCH_CONFIGURES_CPU_MITIGATIONS +config CPU_MITIGATIONS + def_bool y +endif + menu "General architecture-dependent options"
config CRASH_CORE --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -57,6 +57,7 @@ config X86 select ACPI_LEGACY_TABLES_LOOKUP if ACPI select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI select ARCH_32BIT_OFF_T if X86_32 + select ARCH_CONFIGURES_CPU_MITIGATIONS select ARCH_CLOCKSOURCE_INIT select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI select ARCH_HAS_CPU_FINALIZE_INIT @@ -2408,17 +2409,17 @@ config CC_HAS_SLS config CC_HAS_RETURN_THUNK def_bool $(cc-option,-mfunction-return=thunk-extern)
-menuconfig SPECULATION_MITIGATIONS - bool "Mitigations for speculative execution vulnerabilities" +menuconfig CPU_MITIGATIONS + bool "Mitigations for CPU vulnerabilities" default y help - Say Y here to enable options which enable mitigations for - speculative execution hardware vulnerabilities. + Say Y here to enable options which enable mitigations for hardware + vulnerabilities (usually related to speculative execution).
If you say N, all mitigations will be disabled. You really should know what you are doing to say so.
-if SPECULATION_MITIGATIONS +if CPU_MITIGATIONS
config PAGE_TABLE_ISOLATION bool "Remove the kernel mapping in user mode" --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2600,8 +2600,8 @@ enum cpu_mitigations { };
static enum cpu_mitigations cpu_mitigations __ro_after_init = - IS_ENABLED(CONFIG_SPECULATION_MITIGATIONS) ? CPU_MITIGATIONS_AUTO : - CPU_MITIGATIONS_OFF; + IS_ENABLED(CONFIG_CPU_MITIGATIONS) ? CPU_MITIGATIONS_AUTO : + CPU_MITIGATIONS_OFF;
static int __init mitigations_parse_cmdline(char *arg) {