[PATCH v2.5 2/2] x86/Kconfig: Introduce CONFIG_{AMD,INTEL} and conditionalise ucode

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

We eventually want to be able to build a stripped down Xen for a single
platform.  Make a start with CONFIG_{AMD,INTEL} (hidden behind EXPERT, but
available to randconfig), and adjust the microcode logic.

No practical change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Alejandro Vallejo <alejandro.vallejo@xxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxx>
CC: Xenia Ragiadakou <xenia.ragiadakou@xxxxxxx>

I've intentionally ignored the other vendors for now.  They can be put into
Kconfig by whomever figures out the actual dependencies between their init
routines.

v2:
 * Tweak text
v2.5:
 * Fix indentation
 * Rename with _CPU suffixes as requested
---
 xen/arch/x86/Kconfig                 |  2 ++
 xen/arch/x86/Kconfig.cpu             | 22 ++++++++++++++++++++++
 xen/arch/x86/cpu/microcode/Makefile  |  4 ++--
 xen/arch/x86/cpu/microcode/private.h |  9 +++++++++
 4 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100644 xen/arch/x86/Kconfig.cpu

diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index eac77573bd75..d9eacdd7e0fa 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -49,6 +49,8 @@ config HAS_CC_CET_IBT
 
 menu "Architecture Features"
 
+source "arch/x86/Kconfig.cpu"
+
 source "arch/Kconfig"
 
 config PV
diff --git a/xen/arch/x86/Kconfig.cpu b/xen/arch/x86/Kconfig.cpu
new file mode 100644
index 000000000000..b68c41977a3b
--- /dev/null
+++ b/xen/arch/x86/Kconfig.cpu
@@ -0,0 +1,22 @@
+menu "Supported CPU vendors"
+       visible if EXPERT
+
+config AMD_CPU
+       bool "AMD"
+       default y
+       help
+         Detection, tunings and quirks for AMD platforms.
+
+         May be turned off in builds targetting other vendors.  Otherwise,
+         must be enabled for Xen to work suitably on AMD platforms.
+
+config INTEL_CPU
+       bool "Intel"
+       default y
+       help
+         Detection, tunings and quirks for Intel platforms.
+
+         May be turned off in builds targetting other vendors.  Otherwise,
+         must be enabled for Xen to work suitably on Intel platforms.
+
+endmenu
diff --git a/xen/arch/x86/cpu/microcode/Makefile 
b/xen/arch/x86/cpu/microcode/Makefile
index aae235245b06..194ddc239ee3 100644
--- a/xen/arch/x86/cpu/microcode/Makefile
+++ b/xen/arch/x86/cpu/microcode/Makefile
@@ -1,3 +1,3 @@
-obj-y += amd.o
+obj-$(CONFIG_AMD_CPU) += amd.o
 obj-y += core.o
-obj-y += intel.o
+obj-$(CONFIG_INTEL_CPU) += intel.o
diff --git a/xen/arch/x86/cpu/microcode/private.h 
b/xen/arch/x86/cpu/microcode/private.h
index b58611e908aa..bb329933ac89 100644
--- a/xen/arch/x86/cpu/microcode/private.h
+++ b/xen/arch/x86/cpu/microcode/private.h
@@ -70,7 +70,16 @@ struct microcode_ops {
  * support available) and (not) ops->apply_microcode (i.e. read only).
  * Otherwise, all hooks must be filled in.
  */
+#ifdef CONFIG_AMD_CPU
 void ucode_probe_amd(struct microcode_ops *ops);
+#else
+static inline void ucode_probe_amd(struct microcode_ops *ops) {}
+#endif
+
+#ifdef CONFIG_INTEL_CPU
 void ucode_probe_intel(struct microcode_ops *ops);
+#else
+static inline void ucode_probe_intel(struct microcode_ops *ops) {}
+#endif
 
 #endif /* ASM_X86_MICROCODE_PRIVATE_H */
-- 
2.30.2