Add xgetbv()/xsetbv()

src/hulk/cpu.d

@@ -73,6 +73,19 @@ void wrmsr(uint msr, ulong value)
     __asm(`wrmsr`, "{ecx},{edx},{eax}", msr, value >> 32u, value);
 }
 
+ulong xgetbv(uint xcr)
+{
+    return __asm!ulong(`
+            xgetbv
+            shl $$32, %rdx
+            or %rdx, %rax`, "={rax},{ecx},~{rdx}", xcr);
+}
+
+void xsetbv(uint xcr, ulong value)
+{
+    __asm(`xsetbv`, "{ecx},{edx},{eax}", xcr, value >> 32u, value);
+}
+
 ubyte in8(ushort ioaddr)
 {
     return __asm!ubyte("inb %dx, %al", "={al},{dx}", ioaddr);