x86/mtrr: Remove the mtrr_bp_init() stub

Add an IS_ENABLED() check in setup_arch() and call pat_disable()
directly if MTRRs are not supported. This allows to remove the
<asm/memtype.h> include in <asm/mtrr.h>, which pull in lowlevel x86
headers that should not be included for UML builds and will cause build
warnings with a following patch.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211215165612.554426-2-hch@lst.de

arch/x86/include/asm/mtrr.h

@@ -24,8 +24,8 @@
 #define _ASM_X86_MTRR_H
 
 #include <uapi/asm/mtrr.h>
-#include <asm/memtype.h>
 
+void mtrr_bp_init(void);
 
 /*
  * The following functions are for use by other drivers that cannot use
@@ -43,7 +43,6 @@ extern int mtrr_del(int reg, unsigned long base, unsigned long size);
 extern int mtrr_del_page(int reg, unsigned long base, unsigned long size);
 extern void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi);
 extern void mtrr_ap_init(void);
-extern void mtrr_bp_init(void);
 extern void set_mtrr_aps_delayed_init(void);
 extern void mtrr_aps_init(void);
 extern void mtrr_bp_restore(void);
@@ -84,11 +83,6 @@ static inline int mtrr_trim_uncached_memory(unsigned long end_pfn)
 static inline void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi)
 {
 }
-static inline void mtrr_bp_init(void)
-{
-	pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel.");
-}
-
 #define mtrr_ap_init() do {} while (0)
 #define set_mtrr_aps_delayed_init() do {} while (0)
 #define mtrr_aps_init() do {} while (0)

arch/x86/kernel/setup.c

@@ -40,6 +40,7 @@
 #include <asm/kasan.h>
 #include <asm/kaslr.h>
 #include <asm/mce.h>
+#include <asm/memtype.h>
 #include <asm/mtrr.h>
 #include <asm/realmode.h>
 #include <asm/olpc_ofw.h>
@@ -979,7 +980,11 @@ void __init setup_arch(char **cmdline_p)
 	max_pfn = e820__end_of_ram_pfn();
 
 	/* update e820 for memory not covered by WB MTRRs */
-	mtrr_bp_init();
+	if (IS_ENABLED(CONFIG_MTRR))
+		mtrr_bp_init();
+	else
+		pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel.");
+
 	if (mtrr_trim_uncached_memory(max_pfn))
 		max_pfn = e820__end_of_ram_pfn();
 

arch/x86/kvm/mmu/spte.c

@@ -16,6 +16,7 @@
 #include "spte.h"
 
 #include <asm/e820/api.h>
+#include <asm/memtype.h>
 #include <asm/vmx.h>
 
 static bool __read_mostly enable_mmio_caching = true;