x86/resctrl: Move pseudo lock prototypes to include/linux/resctrl.h

The resctrl pseudo-lock feature allows an architecture to allocate data
into particular cache portions, which are then treated as reserved to
avoid that data ever being evicted. Setting this up is deeply architecture
specific as it involves disabling prefetchers etc. It is not possible
to support this kind of feature on arm64. Risc-V is assumed to be the
same.

The prototypes for the architecture code were added to x86's asm/resctrl.h,
with other architectures able to provide stubs for their architecture. This
forces other architectures to provide identical stubs.

Move the prototypes and stubs to linux/resctrl.h, and switch between them
using the existing Kconfig symbol.

Signed-off-by: James Morse <[e-mail]>
Signed-off-by: Borislav Petkov (AMD) <[e-mail]>
Reviewed-by: Reinette Chatre <[e-mail]>
Reviewed-by: Fenghua Yu <[e-mail]>
Tested-by: Fenghua Yu <[e-mail]>
Tested-by: Babu Moger <[e-mail]>
Tested-by: Shaopeng Tan <[e-mail]>
Tested-by: Tony Luck <[e-mail]>
Link: https://lore.kernel.org/[e-mail]

arch/x86/include/asm/resctrl.h

···
 					     enum resctrl_event_id evtid,
 					     void *ctx) { }
 
-u64 resctrl_arch_get_prefetch_disable_bits(void);
-int resctrl_arch_pseudo_lock_fn(void *_plr);
-int resctrl_arch_measure_cycles_lat_fn(void *_plr);
-int resctrl_arch_measure_l2_residency(void *_plr);
-int resctrl_arch_measure_l3_residency(void *_plr);
 void resctrl_cpu_detect(struct cpuinfo_x86 *c);
 
 #else

include/linux/resctrl.h

···
 int resctrl_init(void);
 void resctrl_exit(void);
 
+#ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
+u64 resctrl_arch_get_prefetch_disable_bits(void);
+int resctrl_arch_pseudo_lock_fn(void *_plr);
+int resctrl_arch_measure_cycles_lat_fn(void *_plr);
+int resctrl_arch_measure_l2_residency(void *_plr);
+int resctrl_arch_measure_l3_residency(void *_plr);
+#else
+static inline u64 resctrl_arch_get_prefetch_disable_bits(void) { return 0; }
+static inline int resctrl_arch_pseudo_lock_fn(void *_plr) { return 0; }
+static inline int resctrl_arch_measure_cycles_lat_fn(void *_plr) { return 0; }
+static inline int resctrl_arch_measure_l2_residency(void *_plr) { return 0; }
+static inline int resctrl_arch_measure_l3_residency(void *_plr) { return 0; }
+#endif /* CONFIG_RESCTRL_FS_PSEUDO_LOCK */
 #endif /* _RESCTRL_H */