ptos/amd64: cpu: Add HalKpcrCurrent()

Signed-off-by: Chloe M <chloe@mensia.org>

service/ptos/arch/amd64/cpu/init.c

@@ -7,8 +7,10 @@
  */
 
 #include <hal/kpcr.h>
+#include <ke/bugcheck.h>
 #include <machine/idt.h>
 #include <machine/trap.h>
+#include <machine/msr.h>
 
 /*
  * Initialize interrupts for the current processor
@@ -34,8 +36,28 @@ InitInterrupts(VOID)
     MdIdtLoad();
 }
 
+KPCR *
+HalKpcrCurrent(VOID)
+{
+    KPCR *Kpcr;
+
+    Kpcr = (KPCR *)MdRdmsr(IA32_GS_BASE);
+    if (Kpcr == NULL) {
+        KeBugCheck(
+            BUGCHECK_UNBOUND_RESRC,
+            "KPCR not bound in IA32_GS_BASE\n"
+        );
+    }
+
+    return Kpcr;
+}
+
 VOID
 HalKpcrP1Init(KPCR *Kpcr)
 {
+    /* Initialize interrupts for this core */
     InitInterrupts();
+
+    /* Save the current KPCR */
+    MdWrmsr(IA32_GS_BASE, (UPTR)Kpcr);
 }