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authorSean Christopherson <seanjc@google.com>2024-04-20 03:05:54 +0300
committerBorislav Petkov (AMD) <bp@alien8.de>2024-04-25 16:47:35 +0300
commitfe42754b94a42d08cf9501790afc25c4f6a5f631 (patch)
tree08268547fb378c1b23675d4e760a9ba9f4e08e84
parenta0a8d15a798be4b8f20aca2ba91bf6b688c6a640 (diff)
downloadlinux-fe42754b94a42d08cf9501790afc25c4f6a5f631.tar.xz
cpu: Re-enable CPU mitigations by default for !X86 architectures
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
-rw-r--r--arch/Kconfig8
-rw-r--r--arch/x86/Kconfig11
-rw-r--r--kernel/cpu.c4
3 files changed, 16 insertions, 7 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 65afb1de48b3..30f7930275d8 100644
--- 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 ARCH_HAS_SUBPAGE_FAULTS
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4474bf32d0a4..619a04d5c131 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -62,6 +62,7 @@ config X86
select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
select ARCH_32BIT_OFF_T if X86_32
select ARCH_CLOCKSOURCE_INIT
+ select ARCH_CONFIGURES_CPU_MITIGATIONS
select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
@@ -2488,17 +2489,17 @@ config PREFIX_SYMBOLS
def_bool y
depends on CALL_PADDING && !CFI_CLANG
-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 MITIGATION_PAGE_TABLE_ISOLATION
bool "Remove the kernel mapping in user mode"
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 07ad53b7f119..bb0ff275fb46 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -3207,8 +3207,8 @@ 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)
{