cpuidle, intel_idle: Fix CPUIDLE_FLAG_IBRS

objtool to the rescue:

  vmlinux.o: warning: objtool: intel_idle_ibrs+0x17: call to spec_ctrl_current() leaves .noinstr.text section
  vmlinux.o: warning: objtool: intel_idle_ibrs+0x27: call to wrmsrl.constprop.0() leaves .noinstr.text section
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195540.556912863@infradead.org

arch/x86/kernel/cpu/bugs.c

@@ -86,7 +86,7 @@ void update_spec_ctrl_cond(u64 val)
 		wrmsrl(MSR_IA32_SPEC_CTRL, val);
 }
 
-u64 spec_ctrl_current(void)
+noinstr u64 spec_ctrl_current(void)
 {
 	return this_cpu_read(x86_spec_ctrl_current);
 }

drivers/idle/intel_idle.c

@@ -181,12 +181,12 @@ static __cpuidle int intel_idle_ibrs(struct cpuidle_device *dev,
 	int ret;
 
 	if (smt_active)
-		wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+		native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
 	ret = __intel_idle(dev, drv, index);
 
 	if (smt_active)
-		wrmsrl(MSR_IA32_SPEC_CTRL, spec_ctrl);
+		native_wrmsrl(MSR_IA32_SPEC_CTRL, spec_ctrl);
 
 	return ret;
 }