[XEN PATCH V1] x86/ucode: optional amd/intel ucode build & load

[Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>]

Introduce configuration variables to make it possible to selectively turn
on/off CPU microcode management code in the build for AMD and Intel CPUs.

This is to allow build configuration for a specific CPU, not compile and
load what will not be used anyway.

Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@xxxxxxxx>
---
 xen/arch/x86/Kconfig                | 12 ++++++++++++
 xen/arch/x86/cpu/microcode/Makefile |  4 ++--
 xen/arch/x86/cpu/microcode/core.c   |  5 ++++-
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index d6f3128588..1ee5ae793d 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -350,6 +350,18 @@ config REQUIRE_NX
          was unavailable. However, if enabled, Xen will no longer boot on
          any CPU which is lacking NX support.
 
+config MICROCODE_INTEL
+       bool "Build with Intel CPU ucode support" if EXPERT
+        default y
+       help
+         Support microcode management for Intel processors. If unsure, say Y.
+
+config MICROCODE_AMD
+       bool "Build with AMD CPU ucode support" if EXPERT
+        default y
+       help
+         Support microcode management for AMD K10 family of processors
+         and later. If unsure, say Y.
 endmenu
 
 source "common/Kconfig"
diff --git a/xen/arch/x86/cpu/microcode/Makefile 
b/xen/arch/x86/cpu/microcode/Makefile
index aae235245b..abd0afe8c5 100644
--- a/xen/arch/x86/cpu/microcode/Makefile
+++ b/xen/arch/x86/cpu/microcode/Makefile
@@ -1,3 +1,3 @@
-obj-y += amd.o
 obj-y += core.o
-obj-y += intel.o
+obj-$(CONFIG_MICROCODE_AMD) += amd.o
+obj-$(CONFIG_MICROCODE_INTEL) += intel.o
diff --git a/xen/arch/x86/cpu/microcode/core.c 
b/xen/arch/x86/cpu/microcode/core.c
index 1c9f66ea8a..b7c108f68b 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -865,6 +865,7 @@ int __init early_microcode_init(unsigned long *module_map,
 
     switch ( c->x86_vendor )
     {
+#ifdef CONFIG_MICROCODE_AMD
     case X86_VENDOR_AMD:
         if ( c->x86 >= 0x10 )
         {
@@ -872,11 +873,13 @@ int __init early_microcode_init(unsigned long *module_map,
             can_load = true;
         }
         break;
-
+#endif
+#ifdef CONFIG_MICROCODE_INTEL
     case X86_VENDOR_INTEL:
         ucode_ops = intel_ucode_ops;
         can_load = intel_can_load_microcode();
         break;
+#endif
     }
 
     if ( !ucode_ops.apply_microcode )
-- 
2.25.1