From d6d40e9ecf2aff5b1e265d26f7651e8633eddabd Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Wed, 19 Nov 2025 19:00:55 -0500
Subject: kern/amd64: mp: Load per-core GDT/IDT

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/amd64/cpu/mp.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'sys/arch/amd64/cpu/mp.c')

diff --git a/sys/arch/amd64/cpu/mp.c b/sys/arch/amd64/cpu/mp.c
index 1fdc9f7..6911a49 100644
--- a/sys/arch/amd64/cpu/mp.c
+++ b/sys/arch/amd64/cpu/mp.c
@@ -105,6 +105,9 @@ struct mtrr_save {
     uintptr_t physmask[256];
 } mtrr_save;
 
+extern struct gdtr GDTR;
+extern void idt_load(void);
+
 static struct cpu_info *cpu_list[MAX_CPUS];
 static struct ap_bootspace bs;
 static volatile size_t ap_sync = 0;
@@ -293,6 +296,18 @@ cpu_lm_entry(void)
     atomic_inc_int(&aps_up);
     cpu_list[aps_up] = ci;
 
+    /* Initialize the GDT */
+    memcpy(ci->ap_gdt, (void *)GDTR.offset, GDTR.limit);
+    ci->ap_gdtr.offset = (uintptr_t)&ci->ap_gdt[0];
+    ci->ap_gdtr.limit = GDTR.limit;
+    __asmv(
+        "lgdt %0"
+        :
+        : "m" (ci->ap_gdtr)
+        : "memory"
+    );
+
+    idt_load();
     cpu_idle();
     __builtin_unreachable();
 }
-- 
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