add rdtsc/rdtscp opcode emulation

This might be useful in cases where it's desired to catch rdtsc/rdtscp begin executed only in user-mode.

Disabling rdtsc/rdstcp for user-mode is achieved by setting cr4_t::timestamp_disable flag (it might be needed to set correct value to the shadow CR4 due to patch-guard).

Note: this commit temporarily disables VMWARE_WORKAROUND, until correct solution is implemented.

src/hvpp/hvpp/vcpu.cpp

@@ -47,6 +47,13 @@ vcpu_t::vcpu_t(vmexit_handler& handler) noexcept
   , ept_count_{}
   , ept_index_{}
 
+  //
+  // Initialize timestamp-counter members.
+  //
+  , tsc_entry_{}
+  , tsc_delta_previous_{}
+  , tsc_delta_sum_{}
+
   //
   // Well, this is also not necessary.
   // This member is reset to "false" on each VM-exit in entry_host() method.

src/hvpp/hvpp/vmexit/vmexit_passthrough.cpp

@@ -30,6 +30,18 @@ namespace detail
     static constexpr uint8_t opcode[] = { 0x48, 0x0f, 0x07 };
     return memcmp(address, opcode, sizeof(opcode)) == 0;
   }
+
+  static bool is_rdtsc_instruction(const void* address) noexcept
+  {
+    static constexpr uint8_t opcode[] = { 0x0f, 0x31 };
+    return memcmp(address, opcode, sizeof(opcode)) == 0;
+  }
+
+  static bool is_rdtscp_instruction(const void* address) noexcept
+  {
+    static constexpr uint8_t opcode[] = { 0x0f, 0x01, 0xf9 };
+    return memcmp(address, opcode, sizeof(opcode)) == 0;
+  }
 }
 
 void vmexit_passthrough_handler::setup(vcpu_t& vp) noexcept
@@ -1124,21 +1136,56 @@ void vmexit_passthrough_handler::handle_interrupt(vcpu_t& vp) noexcept
 
         case exception_vector::general_protection:
         {
+          //
+          // 3 bytes are enough to hold either `rdtsc' or `rdtscp'
+          // instruction opcode.
+          //
+          uint8_t buffer[3];
 
-#ifdef HVPP_ENABLE_VMWARE_WORKAROUND
+          auto instruction_length = static_cast<size_t>(vp.exit_instruction_length());
+          auto read_size = std::max(instruction_length, sizeof(buffer));
+
+          if (auto err_va = vp.guest_read_memory(vp.context().rip, buffer, read_size))
+          {
+            hvpp_trace("handle_interrupt (general_protection) - read_guest_memory(%p, %u) failed, injecting #PF",
+                       vp.context().rip,
+                       instruction_length);
+
+            write<cr2_t>({ err_va.value() });
+            vp.interrupt_inject(interrupt::page_fault);
+            vp.suppress_rip_adjust();
+
+            return;
+          }
 
           //
-          // VMWare I/O backdoor (port 0x5658/0x5659) workaround.
+          // Compare copied memory to `rdtsc' & `rdtscp' instructions.
           //
-          cr3_guard _{ vp.guest_cr3() };
-
-          vmx::exit_qualification_io_instruction_t exit_qualification;
-          if (try_decode_io_instruction(vp.context(), exit_qualification))
+          if (detail::is_rdtsc_instruction(buffer))
+          {
+            handle_emulate_rdtsc(vp);
+            return;
+          }
+          else if (detail::is_rdtscp_instruction(buffer))
           {
-            ia32_asm_io_with_context(exit_qualification, vp.context());
+            handle_emulate_rdtscp(vp);
             return;
           }
 
+#ifdef HVPP_ENABLE_VMWARE_WORKAROUND
+
+//           //
+//           // VMWare I/O backdoor (port 0x5658/0x5659) workaround.
+//           //
+//           cr3_guard _{ vp.guest_cr3() };
+//
+//           vmx::exit_qualification_io_instruction_t exit_qualification;
+//           if (try_decode_io_instruction(vp.context(), exit_qualification))
+//           {
+//             ia32_asm_io_with_context(exit_qualification, vp.context());
+//             return;
+//           }
+
 #endif
 
           break;
@@ -1323,4 +1370,14 @@ void vmexit_passthrough_handler::handle_emulate_sysret(vcpu_t& vp) noexcept
   vp.guest_ss(ss);
 }
 
+void vmexit_passthrough_handler::handle_emulate_rdtsc(vcpu_t& vp) noexcept
+{
+  handle_execute_rdtsc(vp);
+}
+
+void vmexit_passthrough_handler::handle_emulate_rdtscp(vcpu_t& vp) noexcept
+{
+  handle_execute_rdtscp(vp);
+}
+
 }

src/hvpp/hvpp/vmexit/vmexit_passthrough.h

@@ -66,6 +66,8 @@ class vmexit_passthrough_handler
 
     virtual void handle_emulate_syscall(vcpu_t& vp) noexcept;
     virtual void handle_emulate_sysret(vcpu_t& vp) noexcept;
+    virtual void handle_emulate_rdtsc(vcpu_t& vp) noexcept;
+    virtual void handle_emulate_rdtscp(vcpu_t& vp) noexcept;
 };
 
 }