[tip: x86/cpu] x86/cpufeatures: Add {REQUIRED,DISABLED} feature configs

From: tip-bot2 for H. Peter Anvin (Intel)
Date: Mon Mar 10 2025 - 04:18:51 EST

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID: dc6e8bfc0c9e27cbfed27c7ed50c71205a7c9551
Gitweb: https://git.kernel.org/tip/dc6e8bfc0c9e27cbfed27c7ed50c71205a7c9551
Author: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
AuthorDate: Fri, 28 Feb 2025 00:23:35 -08:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Mon, 10 Mar 2025 09:02:30 +01:00

x86/cpufeatures: Add {REQUIRED,DISABLED} feature configs

Required and disabled feature masks completely rely on build configs,
i.e., once a build config is fixed, so are the feature masks.

To prepare for auto-generating the <asm/cpufeaturemasks.h> header
with required and disabled feature masks based on a build config,
add feature Kconfig items:

- X86_REQUIRED_FEATURE_x
- X86_DISABLED_FEATURE_x

each of which may be set to "y" if and only if its preconditions from
current build config are met.

Signed-off-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250228082338.73859-3-xin@xxxxxxxxx
---
arch/x86/Kconfig | 2 +-
arch/x86/Kconfig.cpufeatures | 201 ++++++++++++++++++++++++++++++++++-
2 files changed, 203 insertions(+)
create mode 100644 arch/x86/Kconfig.cpufeatures

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 017035f..7caf2fd 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -3128,4 +3128,6 @@ config HAVE_ATOMIC_IOMAP

source "arch/x86/kvm/Kconfig"

+source "arch/x86/Kconfig.cpufeatures"
+
source "arch/x86/Kconfig.assembler"
diff --git a/arch/x86/Kconfig.cpufeatures b/arch/x86/Kconfig.cpufeatures
new file mode 100644
index 0000000..e12d5b7
--- /dev/null
+++ b/arch/x86/Kconfig.cpufeatures
@@ -0,0 +1,201 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# x86 feature bits (see arch/x86/include/asm/cpufeatures.h) that are
+# either REQUIRED to be enabled, or DISABLED (always ignored) for this
+# particular compile-time configuration. The tests for these features
+# are turned into compile-time constants via the generated
+# <asm/cpufeaturemasks.h>.
+#
+# The naming of these variables *must* match asm/cpufeatures.h, e.g.,
+# X86_FEATURE_ALWAYS <==> X86_REQUIRED_FEATURE_ALWAYS
+# X86_FEATURE_FRED <==> X86_DISABLED_FEATURE_FRED
+#
+# And these REQUIRED and DISABLED config options are manipulated in an
+# AWK script as the following example:
+#
+# +----------------------+
+# | X86_FRED = y ? |
+# +----------------------+
+# / \
+# Y / \ N
+# +-------------------------------------+ +-------------------------------+
+# | X86_DISABLED_FEATURE_FRED undefined | | X86_DISABLED_FEATURE_FRED = y |
+# +-------------------------------------+ +-------------------------------+
+# |
+# |
+# +-------------------------------------------+ |
+# | X86_FEATURE_FRED: feature word 12, bit 17 | ---->|
+# +-------------------------------------------+ |
+# |
+# |
+# +-------------------------------+
+# | set bit 17 of DISABLED_MASK12 |
+# +-------------------------------+
+#
+
+config X86_REQUIRED_FEATURE_ALWAYS
+ def_bool y
+
+config X86_REQUIRED_FEATURE_NOPL
+ def_bool y
+ depends on X86_64 || X86_P6_NOP
+
+config X86_REQUIRED_FEATURE_CX8
+ def_bool y
+ depends on X86_CX8
+
+# this should be set for all -march=.. options where the compiler
+# generates cmov.
+config X86_REQUIRED_FEATURE_CMOV
+ def_bool y
+ depends on X86_CMOV
+
+# this should be set for all -march= options where the compiler
+# generates movbe.
+config X86_REQUIRED_FEATURE_MOVBE
+ def_bool y
+ depends on MATOM
+
+config X86_REQUIRED_FEATURE_CPUID
+ def_bool y
+ depends on X86_64
+
+config X86_REQUIRED_FEATURE_UP
+ def_bool y
+ depends on !SMP
+
+config X86_REQUIRED_FEATURE_FPU
+ def_bool y
+ depends on !MATH_EMULATION
+
+config X86_REQUIRED_FEATURE_PAE
+ def_bool y
+ depends on X86_64 || X86_PAE
+
+config X86_REQUIRED_FEATURE_PSE
+ def_bool y
+ depends on X86_64 && !PARAVIRT_XXL
+
+config X86_REQUIRED_FEATURE_PGE
+ def_bool y
+ depends on X86_64 && !PARAVIRT_XXL
+
+config X86_REQUIRED_FEATURE_MSR
+ def_bool y
+ depends on X86_64
+
+config X86_REQUIRED_FEATURE_FXSR
+ def_bool y
+ depends on X86_64
+
+config X86_REQUIRED_FEATURE_XMM
+ def_bool y
+ depends on X86_64
+
+config X86_REQUIRED_FEATURE_XMM2
+ def_bool y
+ depends on X86_64
+
+config X86_REQUIRED_FEATURE_LM
+ def_bool y
+ depends on X86_64
+
+config X86_DISABLED_FEATURE_UMIP
+ def_bool y
+ depends on !X86_UMIP
+
+config X86_DISABLED_FEATURE_VME
+ def_bool y
+ depends on X86_64
+
+config X86_DISABLED_FEATURE_K6_MTRR
+ def_bool y
+ depends on X86_64
+
+config X86_DISABLED_FEATURE_CYRIX_ARR
+ def_bool y
+ depends on X86_64
+
+config X86_DISABLED_FEATURE_CENTAUR_MCR
+ def_bool y
+ depends on X86_64
+
+config X86_DISABLED_FEATURE_PCID
+ def_bool y
+ depends on !X86_64
+
+config X86_DISABLED_FEATURE_PKU
+ def_bool y
+ depends on !X86_INTEL_MEMORY_PROTECTION_KEYS
+
+config X86_DISABLED_FEATURE_OSPKE
+ def_bool y
+ depends on !X86_INTEL_MEMORY_PROTECTION_KEYS
+
+config X86_DISABLED_FEATURE_LA57
+ def_bool y
+ depends on !X86_5LEVEL
+
+config X86_DISABLED_FEATURE_PTI
+ def_bool y
+ depends on !MITIGATION_PAGE_TABLE_ISOLATION
+
+config X86_DISABLED_FEATURE_RETPOLINE
+ def_bool y
+ depends on !MITIGATION_RETPOLINE
+
+config X86_DISABLED_FEATURE_RETPOLINE_LFENCE
+ def_bool y
+ depends on !MITIGATION_RETPOLINE
+
+config X86_DISABLED_FEATURE_RETHUNK
+ def_bool y
+ depends on !MITIGATION_RETHUNK
+
+config X86_DISABLED_FEATURE_UNRET
+ def_bool y
+ depends on !MITIGATION_UNRET_ENTRY
+
+config X86_DISABLED_FEATURE_CALL_DEPTH
+ def_bool y
+ depends on !MITIGATION_CALL_DEPTH_TRACKING
+
+config X86_DISABLED_FEATURE_LAM
+ def_bool y
+ depends on !ADDRESS_MASKING
+
+config X86_DISABLED_FEATURE_ENQCMD
+ def_bool y
+ depends on !INTEL_IOMMU_SVM
+
+config X86_DISABLED_FEATURE_SGX
+ def_bool y
+ depends on !X86_SGX
+
+config X86_DISABLED_FEATURE_XENPV
+ def_bool y
+ depends on !XEN_PV
+
+config X86_DISABLED_FEATURE_TDX_GUEST
+ def_bool y
+ depends on !INTEL_TDX_GUEST
+
+config X86_DISABLED_FEATURE_USER_SHSTK
+ def_bool y
+ depends on !X86_USER_SHADOW_STACK
+
+config X86_DISABLED_FEATURE_IBT
+ def_bool y
+ depends on !X86_KERNEL_IBT
+
+config X86_DISABLED_FEATURE_FRED
+ def_bool y
+ depends on !X86_FRED
+
+config X86_DISABLED_FEATURE_SEV_SNP
+ def_bool y
+ depends on !KVM_AMD_SEV
+
+config X86_DISABLED_FEATURE_INVLPGB
+ def_bool y
+ depends on !BROADCAST_TLB_FLUSH