x86: Reload cpuid after loading microcode for the BSP

Right now, we're doing very early init - then parsing boot modules - and only then doing the microcode load for the BSP. This results in having possibly stale cpuid info that doesn't correspond to the current microcode. Fix that by reloading if cpu 0. Signed-off-by: Pedro Falcato <[email protected]>
heatd · Nov 30, 2024 · cb8f96b · cb8f96b
1 parent 5337062
commit cb8f96b
Showing 1 changed file with 10 additions and 1 deletion.
diff --git a/kernel/arch/x86_64/cpu.cpp b/kernel/arch/x86_64/cpu.cpp
@@ -84,13 +84,22 @@ uint64_t x86_get_tsc_rate(void)
 
 extern "C" void intel_ucode_load(void);
 
+static void __cpu_identify(void);
+
 void x86_load_ucode(void)
 {
     if (bootcpu_info.manufacturer == X86_CPU_MANUFACTURER_INTEL)
         intel_ucode_load();
+
+    if (get_cpu_nr() == 0)
+    {
+        /* If we're cpu 0, try to reload cpuid bits, since we might be loading ucode a little after
+         * the initial cpu_identify. */
+        __cpu_identify();
+    }
 }
 
-void __cpu_identify(void)
+static void __cpu_identify(void)
 {
     uint32_t eax = 0;
     uint32_t ebx = 0;