arm64: kconfig: group the v8.1 features together

ARMv8 CPUs do not support any of the v8.1 features, so group them
together in Kconfig to make it clear that they're part of 8.1 and not
relevant to older cores.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/Kconfig

@@ -481,23 +481,6 @@ config ARM64_VA_BITS
 	default 42 if ARM64_VA_BITS_42
 	default 48 if ARM64_VA_BITS_48
 
-config ARM64_HW_AFDBM
-	bool "Support for hardware updates of the Access and Dirty page flags"
-	default y
-	help
-	  The ARMv8.1 architecture extensions introduce support for
-	  hardware updates of the access and dirty information in page
-	  table entries. When enabled in TCR_EL1 (HA and HD bits) on
-	  capable processors, accesses to pages with PTE_AF cleared will
-	  set this bit instead of raising an access flag fault.
-	  Similarly, writes to read-only pages with the DBM bit set will
-	  clear the read-only bit (AP[2]) instead of raising a
-	  permission fault.
-
-	  Kernels built with this configuration option enabled continue
-	  to work on pre-ARMv8.1 hardware and the performance impact is
-	  minimal. If unsure, say Y.
-
 config CPU_BIG_ENDIAN
        bool "Build big-endian kernel"
        help
@@ -605,32 +588,6 @@ config FORCE_MAX_ZONEORDER
 	default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)
 	default "11"
 
-config ARM64_PAN
-	bool "Enable support for Privileged Access Never (PAN)"
-	default y
-	help
-	 Privileged Access Never (PAN; part of the ARMv8.1 Extensions)
-	 prevents the kernel or hypervisor from accessing user-space (EL0)
-	 memory directly.
-
-	 Choosing this option will cause any unprotected (not using
-	 copy_to_user et al) memory access to fail with a permission fault.
-
-	 The feature is detected at runtime, and will remain as a 'nop'
-	 instruction if the cpu does not implement the feature.
-
-config ARM64_LSE_ATOMICS
-	bool "ARMv8.1 atomic instructions"
-	help
-	  As part of the Large System Extensions, ARMv8.1 introduces new
-	  atomic instructions that are designed specifically to scale in
-	  very large systems.
-
-	  Say Y here to make use of these instructions for the in-kernel
-	  atomic routines. This incurs a small overhead on CPUs that do
-	  not support these instructions and requires the kernel to be
-	  built with binutils >= 2.25.
-
 menuconfig ARMV8_DEPRECATED
 	bool "Emulate deprecated/obsolete ARMv8 instructions"
 	depends on COMPAT
@@ -698,6 +655,53 @@ config SETEND_EMULATION
 	  If unsure, say Y
 endif
 
+menu "ARMv8.1 architectural features"
+
+config ARM64_HW_AFDBM
+	bool "Support for hardware updates of the Access and Dirty page flags"
+	default y
+	help
+	  The ARMv8.1 architecture extensions introduce support for
+	  hardware updates of the access and dirty information in page
+	  table entries. When enabled in TCR_EL1 (HA and HD bits) on
+	  capable processors, accesses to pages with PTE_AF cleared will
+	  set this bit instead of raising an access flag fault.
+	  Similarly, writes to read-only pages with the DBM bit set will
+	  clear the read-only bit (AP[2]) instead of raising a
+	  permission fault.
+
+	  Kernels built with this configuration option enabled continue
+	  to work on pre-ARMv8.1 hardware and the performance impact is
+	  minimal. If unsure, say Y.
+
+config ARM64_PAN
+	bool "Enable support for Privileged Access Never (PAN)"
+	default y
+	help
+	 Privileged Access Never (PAN; part of the ARMv8.1 Extensions)
+	 prevents the kernel or hypervisor from accessing user-space (EL0)
+	 memory directly.
+
+	 Choosing this option will cause any unprotected (not using
+	 copy_to_user et al) memory access to fail with a permission fault.
+
+	 The feature is detected at runtime, and will remain as a 'nop'
+	 instruction if the cpu does not implement the feature.
+
+config ARM64_LSE_ATOMICS
+	bool "Atomic instructions"
+	help
+	  As part of the Large System Extensions, ARMv8.1 introduces new
+	  atomic instructions that are designed specifically to scale in
+	  very large systems.
+
+	  Say Y here to make use of these instructions for the in-kernel
+	  atomic routines. This incurs a small overhead on CPUs that do
+	  not support these instructions and requires the kernel to be
+	  built with binutils >= 2.25.
+
+endmenu
+
 endmenu
 
 menu "Boot options"