cpuidle, intel_idle: Fix CPUIDLE_FLAG_INIT_XSTATE

Fix instrumentation bugs objtool found:

vmlinux.o: warning: objtool: intel_idle_s2idle+0xd5: call to fpu_idle_fpregs() leaves .noinstr.text section
vmlinux.o: warning: objtool: intel_idle_xstate+0x11: call to fpu_idle_fpregs() leaves .noinstr.text section
vmlinux.o: warning: objtool: fpu_idle_fpregs+0x9: call to xfeatures_in_use() leaves .noinstr.text section

Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Tested-by: Tony Lindgren <[e-mail]>
Tested-by: Ulf Hansson <[e-mail]>
Acked-by: Rafael J. Wysocki <[e-mail]>
Acked-by: Frederic Weisbecker <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/x86/include/asm/fpu/xcr.h

···
 #define XCR_XFEATURE_ENABLED_MASK	0x00000000
 #define XCR_XFEATURE_IN_USE_MASK	0x00000001
 
-static inline u64 xgetbv(u32 index)
+static __always_inline u64 xgetbv(u32 index)
 {
 	u32 eax, edx;
 
···
  *
  * Callers should check X86_FEATURE_XGETBV1.
  */
-static inline u64 xfeatures_in_use(void)
+static __always_inline u64 xfeatures_in_use(void)
 {
 	return xgetbv(XCR_XFEATURE_IN_USE_MASK);
 }

arch/x86/include/asm/special_insns.h

···
 	return 0;
 }
 
-static inline void tile_release(void)
+static __always_inline void tile_release(void)
 {
 	/*
 	 * Instruction opcode for TILERELEASE; supported in binutils

arch/x86/kernel/fpu/core.c

···
  * Initialize register state that may prevent from entering low-power idle.
  * This function will be invoked from the cpuidle driver only when needed.
  */
-void fpu_idle_fpregs(void)
+noinstr void fpu_idle_fpregs(void)
 {
 	/* Note: AMX_TILE being enabled implies XGETBV1 support */
 	if (cpu_feature_enabled(X86_FEATURE_AMX_TILE) &&
 	    (xfeatures_in_use() & XFEATURE_MASK_XTILE)) {
 		tile_release();
-		fpregs_deactivate(&current->thread.fpu);
+		__this_cpu_write(fpu_fpregs_owner_ctx, NULL);
 	}
 }