implement model specific register calls

1 files changed, 29 insertions, 0 deletions

diff --git a/arch/x86_64/src/memory/cpu/msr.cpp b/arch/x86_64/src/memory/cpu/msr.cpp
new file mode 100644
index 0000000..3a917c9
--- /dev/null
+++ b/arch/x86_64/src/memory/cpu/msr.cpp
@@ -0,0 +1,29 @@
+#include "arch/memory/cpu/msr.hpp"
+
+namespace teachos::arch::memory::cpu
+{
+  uint64_t read_msr(uint32_t msr)
+  {
+    uint32_t low, high;
+    asm volatile("rdmsr" : "=a"(low), "=d"(high) : "c"(msr));
+    return (static_cast<uint64_t>(high) << 32) | low;
+  }
+
+  void write_msr(uint32_t msr, uint64_t value)
+  {
+    uint32_t low = value & 0xFFFFFFFF;
+    uint32_t high = value >> 32;
+    asm volatile("wrmsr"
+                 : /* no output from call */
+                 : "c"(msr), "a"(low), "d"(high));
+  }
+
+  void set_msr_bit(msr_flags flag)
+  {
+    uint64_t efer = read_msr(IA32_EFER);
+    write_msr(IA32_EFER, static_cast<uint64_t>(flag) | efer);
+  }
+
+  void enable_nxe_bit() { set_msr_bit(msr_flags::NXE); }
+
+}  // namespace teachos::arch::memory::cpu