Set IA32_TSC_AUX if present.

src/arch/x86_64/misc.rs

 use x86::controlregs::Cr4;
 use x86::cpuid::ExtendedFeatures;
 
-pub unsafe fn init() {
-    let has_ext_feat = |feat: fn(ExtendedFeatures) -> bool| crate::cpuid::cpuid_always().get_extended_feature_info().map_or(false, feat);
+use crate::cpuid::cpuid_always;
+
+pub unsafe fn init(cpu_id: usize) {
+    let has_ext_feat = |feat: fn(ExtendedFeatures) -> bool| {
+        cpuid_always()
+            .get_extended_feature_info()
+            .map_or(false, feat)
+    };
 
     if has_ext_feat(|feat| feat.has_umip()) {
         // UMIP (UserMode Instruction Prevention) forbids userspace from calling SGDT, SIDT, SLDT,
@@ -25,4 +31,8 @@ pub unsafe fn init() {
         // Clear CLAC in (the probably unlikely) case the bootloader set it earlier.
         x86::bits64::rflags::clac();
     }
+
+    if let Some(feats) = cpuid_always().get_extended_processor_and_feature_identifiers() && feats.has_rdtscp() {
+        x86::msr::wrmsr(x86::msr::IA32_TSC_AUX, cpu_id as u64);
+    }
 }

src/arch/x86_64/start.rs

@@ -155,7 +155,7 @@ pub unsafe extern fn kstart(args_ptr: *const KernelArgs) -> ! {
         log::init();
 
         // Initialize miscellaneous processor features
-        misc::init();
+        misc::init(0);
 
         // Initialize devices
         device::init();
@@ -234,7 +234,7 @@ pub unsafe extern fn kstart_ap(args_ptr: *const KernelArgsAp) -> ! {
         interrupt::syscall::init();
 
         // Initialize miscellaneous processor features
-        misc::init();
+        misc::init(cpu_id);
 
         // Initialize devices (for AP)
         device::init_ap();