void StaticGpaMissingHandler(const uint64_t Gpa) {
  const Gpa_t AlignedGpa = Gpa_t(Gpa).Align();
  BochsHooksDebugPrint("GpaMissingHandler: Mapping GPA {:#x} ({:#x}) ..\n",
                       AlignedGpa, Gpa);

  const void *DmpPage =
      reinterpret_cast<BochscpuBackend_t *>(g_Backend)->GetPhysicalPage(
          AlignedGpa);
  if (DmpPage == nullptr) {
    BochsHooksDebugPrint(
        "GpaMissingHandler: GPA {:#x} is not mapped in the dump.\n",
        AlignedGpa);
  }

  uint8_t *Page = (uint8_t *)aligned_alloc(Page::Size, Page::Size);
  if (Page == nullptr) {
    fmt::print("Failed to allocate memory in GpaMissingHandler.\n");
    __debugbreak();
  }

  if (DmpPage) {

    //
    // Copy the dump page into the new page.
    //

    memcpy(Page, DmpPage, Page::Size);

  } else {

    //
    // Fake it 'till you make it.
    //

    memset(Page, 0, Page::Size);
  }

  //
  // Tell bochscpu that we inserted a page backing the requested GPA.
  //

  bochscpu_mem_page_insert(AlignedGpa.U64(), Page);
}

void BochscpuBackend_t::LoadState(const CpuState_t &State) {
  bochscpu_cpu_state_t Bochs;
  memset(&Bochs, 0, sizeof(Bochs));

  Seed_ = State.Seed;
  Bochs.bochscpu_seed = State.Seed;
  Bochs.rax = State.Rax;
  Bochs.rbx = State.Rbx;
//...
  Bochs.rflags = State.Rflags;
  Bochs.tsc = State.Tsc;
  Bochs.apic_base = State.ApicBase;
  Bochs.sysenter_cs = State.SysenterCs;
  Bochs.sysenter_esp = State.SysenterEsp;
  Bochs.sysenter_eip = State.SysenterEip;
  Bochs.pat = State.Pat;
  Bochs.efer = uint32_t(State.Efer.Flags);
  Bochs.star = State.Star;
  Bochs.lstar = State.Lstar;
  Bochs.cstar = State.Cstar;
  Bochs.sfmask = State.Sfmask;
  Bochs.kernel_gs_base = State.KernelGsBase;
  Bochs.tsc_aux = State.TscAux;
  Bochs.fpcw = State.Fpcw;
  Bochs.fpsw = State.Fpsw;
  Bochs.fptw = State.Fptw;
  Bochs.cr0 = uint32_t(State.Cr0.Flags);
  Bochs.cr2 = State.Cr2;
  Bochs.cr3 = State.Cr3;
  Bochs.cr4 = uint32_t(State.Cr4.Flags);
  Bochs.cr8 = State.Cr8;
  Bochs.xcr0 = State.Xcr0;
  Bochs.dr0 = State.Dr0;
  Bochs.dr1 = State.Dr1;
  Bochs.dr2 = State.Dr2;
  Bochs.dr3 = State.Dr3;
  Bochs.dr6 = State.Dr6;
  Bochs.dr7 = State.Dr7;
  Bochs.mxcsr = State.Mxcsr;
  Bochs.mxcsr_mask = State.MxcsrMask;
  Bochs.fpop = State.Fpop;

#define SEG(_Bochs_, _Whv_)                                                    \
  {                                                                            \
    Bochs._Bochs_.attr = State._Whv_.Attr;                                     \
    Bochs._Bochs_.base = State._Whv_.Base;                                     \
    Bochs._Bochs_.limit = State._Whv_.Limit;                                   \
    Bochs._Bochs_.present = State._Whv_.Present;                               \
    Bochs._Bochs_.selector = State._Whv_.Selector;                             \
  }

  SEG(es, Es);
  SEG(cs, Cs);
  SEG(ss, Ss);
  SEG(ds, Ds);
  SEG(fs, Fs);
  SEG(gs, Gs);
  SEG(tr, Tr);
  SEG(ldtr, Ldtr);

#undef SEG

#define GLOBALSEG(_Bochs_, _Whv_)                                              \
  {                                                                            \
    Bochs._Bochs_.base = State._Whv_.Base;                                     \
    Bochs._Bochs_.limit = State._Whv_.Limit;                                   \
  }

  GLOBALSEG(gdtr, Gdtr);
  GLOBALSEG(idtr, Idtr);

  // ...
  bochscpu_cpu_set_state(Cpu_, &Bochs);
}

//
// Prepare the hooks.
//

Hooks_.ctx = this;
Hooks_.after_execution = StaticAfterExecutionHook;
Hooks_.before_execution = StaticBeforeExecutionHook;
Hooks_.lin_access = StaticLinAccessHook;
Hooks_.interrupt = StaticInterruptHook;
Hooks_.exception = StaticExceptionHook;
Hooks_.phy_access = StaticPhyAccessHook;
Hooks_.tlb_cntrl = StaticTlbControlHook;

void BochscpuBackend_t::BeforeExecutionHook(
        /*void *Context, */ uint32_t, void *) {

  //
  // Grab the rip register off the cpu.
  //

  const Gva_t Rip = Gva_t(bochscpu_cpu_rip(Cpu_));

  //
  // Keep track of new code coverage or log into the trace file.
  //

  const auto &Res = AggregatedCodeCoverage_.emplace(Rip);
  if (Res.second) {
    LastNewCoverage_.emplace(Rip);
  }

  // ...
}

//
// Lift off.
//

bochscpu_cpu_run(Cpu_, HookChain_);

void BochscpuBackend_t::BeforeExecutionHook(
        /*void *Context, */ uint32_t, void *) {

  //
  // Grab the rip register off the cpu.
  //

  const Gva_t Rip = Gva_t(bochscpu_cpu_rip(Cpu_));

  // ...

  //
  // Handle breakpoints.
  //

  if (Breakpoints_.contains(Rip)) {
    Breakpoints_.at(Rip)(this);
  }
}

void BochscpuBackend_t::AfterExecutionHook(/*void *Context, */ uint32_t,
                                           void *) {

  //
  // Keep track of the instructions executed.
  //

  RunStats_.NumberInstructionsExecuted++;

  //
  // Check the instruction limit.
  //

  if (InstructionLimit_ > 0 &&
      RunStats_.NumberInstructionsExecuted > InstructionLimit_) {

    //
    // If we're over the limit, we stop the cpu.
    //

    BochsHooksDebugPrint("Over the instruction limit ({}), stopping cpu.\n",
                         InstructionLimit_);
    TestcaseResult_ = Timedout_t();
    bochscpu_cpu_stop(Cpu_);
  }
}

void BochscpuBackend_t::BeforeExecutionHook(
        /*void *Context, */ uint32_t, void *) {

  //
  // Grab the rip register off the cpu.
  //

  const Gva_t Rip = Gva_t(bochscpu_cpu_rip(Cpu_));

  //
  // Keep track of new code coverage or log into the trace file.
  //

  const auto &Res = AggregatedCodeCoverage_.emplace(Rip);
  if (Res.second) {
    LastNewCoverage_.emplace(Rip);
  }

void BochscpuBackend_t::LinAccessHook(/*void *Context, */ uint32_t,
                                      uint64_t VirtualAddress,
                                      uint64_t PhysicalAddress, uintptr_t Len,
                                      uint32_t, uint32_t MemAccess) {

  // ...

  //
  // If this is not a write access, we don't care to go further.
  //

  if (MemAccess != BOCHSCPU_HOOK_MEM_WRITE &&
      MemAccess != BOCHSCPU_HOOK_MEM_RW) {
    return;
  }

  //
  // Adding the physical address the set of dirty GPAs.
  // We don't use DirtyVirtualMemoryRange here as we need to
  // do a GVA->GPA translation which is a bit costly.
  //

  DirtyGpa(Gpa_t(PhysicalAddress));
}

bool BochscpuBackend_t::Restore(const CpuState_t &CpuState) {
  // ...
  //
  // Restore physical memory.
  //

  uint8_t ZeroPage[Page::Size];
  memset(ZeroPage, 0, sizeof(ZeroPage));
  for (const auto DirtyGpa : DirtyGpas_) {
    const uint8_t *Hva = DmpParser_.GetPhysicalPage(DirtyGpa.U64());

    //
    // As we allocate physical memory pages full of zeros when
    // the guest tries to access a GPA that isn't present in the dump,
    // we need to be able to restore those. It's easy, if the Hva is nullptr,
    // we point it to a zero page.
    //

    if (Hva == nullptr) {
      Hva = ZeroPage;
    }

    bochscpu_mem_phy_write(DirtyGpa.U64(), Hva, Page::Size);
  }

  //
  // Empty the set.
  //

  DirtyGpas_.clear();

  // ...
  return true;
}

class LibfuzzerMutator_t {
  using CustomMutatorFunc_t =
      decltype(fuzzer::ExternalFunctions::LLVMFuzzerCustomMutator);
  fuzzer::Random Rand_;
  fuzzer::MutationDispatcher Mut_;
  std::unique_ptr<fuzzer::Unit> CrossOverWith_;

public:
  explicit LibfuzzerMutator_t(std::mt19937_64 &Rng);

  size_t Mutate(uint8_t *Data, const size_t DataLen, const size_t MaxSize);
  void RegisterCustomMutator(const CustomMutatorFunc_t F);
  void SetCrossOverWith(const Testcase_t &Testcase);
};

class HonggfuzzMutator_t {
  honggfuzz::dynfile_t DynFile_;
  honggfuzz::honggfuzz_t Global_;
  std::mt19937_64 &Rng_;
  honggfuzz::run_t Run_;

public:
  explicit HonggfuzzMutator_t(std::mt19937_64 &Rng);
  size_t Mutate(uint8_t *Data, const size_t DataLen, const size_t MaxSize);
  void SetCrossOverWith(const Testcase_t &Testcase);
};

//
    // If the coverage size has changed, it means that this testcase
    // provided new coverage indeed.
    //

    const bool NewCoverage = Coverage_.size() > SizeBefore;
    if (NewCoverage) {

      //
      // Allocate a test that will get moved into the corpus and maybe
      // saved on disk.
      //

      Testcase_t Testcase((uint8_t *)ReceivedTestcase.data(),
                          ReceivedTestcase.size());

      //
      // Before moving the buffer into the corpus, set up cross over with
      // it.
      //

      Mutator_->SetCrossOverWith(Testcase);

      //
      // Ready to move the buffer into the corpus now.
      //

      Corpus_.SaveTestcase(Result, std::move(Testcase));
    }
  }

  // [...]

  //
  // If we get here, it means that we are ready to mutate.
  // First thing we do is to grab a seed.
  //

  const Testcase_t *Testcase = Corpus_.PickTestcase();
  if (!Testcase) {
    fmt::print("The corpus is empty, exiting\n");
    std::abort();
  }

  //
  // If the testcase is too big, abort as this should not happen.
  //

  if (Testcase->BufferSize_ > Opts_.TestcaseBufferMaxSize) {
    fmt::print(
        "The testcase buffer len is bigger than the testcase buffer max "
        "size.\n");
    std::abort();
  }

  //
  // Copy the input in a buffer we're going to mutate.
  //

  memcpy(ScratchBuffer_.data(), Testcase->Buffer_.get(),
          Testcase->BufferSize_);

  //
  // Mutate in the scratch buffer.
  //

  const size_t TestcaseBufferSize =
      Mutator_->Mutate(ScratchBuffer_.data(), Testcase->BufferSize_,
                        Opts_.TestcaseBufferMaxSize);

  //
  // Copy the testcase in its own buffer before sending it to the
  // consumer.
  //

  TestcaseContent.resize(TestcaseBufferSize);
  memcpy(TestcaseContent.data(), ScratchBuffer_.data(), TestcaseBufferSize);

void BochscpuBackend_t::TlbControlHook(/*void *Context, */ uint32_t,
                                       uint32_t What, uint64_t NewCrValue) {

  //
  // We only care about CR3 changes.
  //

  if (What != BOCHSCPU_HOOK_TLB_CR3) {
    return;
  }

  //
  // And we only care about it when the CR3 value is actually different from
  // when we started the testcase.
  //

  if (NewCrValue == InitialCr3_) {
    return;
  }

  //
  // Stop the cpu as we don't want to be context-switching.
  //

  BochsHooksDebugPrint("The cr3 register is getting changed ({:#x})\n",
                       NewCrValue);
  BochsHooksDebugPrint("Stopping cpu.\n");
  TestcaseResult_ = Cr3Change_t();
  bochscpu_cpu_stop(Cpu_);
}

bool Ida64ConfigureFsHandleTable(const fs::path &GuestFilesPath) {

  //
  // Those files are files we want to redirect to host files. When there is
  // a hooked i/o targeted to one of them, we deliver the i/o on the host
  // by calling the appropriate syscalls and proxy back the result to the
  // guest.
  //

  const std::vector<std::u16string> GuestFiles = {
      uR"(\??\C:\Program Files\IDA Pro 7.5\ida.key)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\ida.cfg)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\noret.cfg)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\pe.cfg)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\plugins\plugins.cfg)"};

  for (const auto &GuestFile : GuestFiles) {
    const size_t LastSlash = GuestFile.find_last_of(uR"(\)");
    if (LastSlash == GuestFile.npos) {
      fmt::print("Expected a / in {}\n", u16stringToString(GuestFile));
      return false;
    }

    const std::u16string GuestFilename = GuestFile.substr(LastSlash + 1);
    const fs::path HostFile(GuestFilesPath / GuestFilename);

    size_t BufferSize = 0;
    const auto Buffer = ReadFile(HostFile, BufferSize);
    if (Buffer == nullptr || BufferSize == 0) {
      fmt::print("Expected to find {}.\n", HostFile.string());
      return false;
    }

    g_FsHandleTable.MapExistingGuestFile(GuestFile.c_str(), Buffer.get(),
                                         BufferSize);
  }

  g_FsHandleTable.MapExistingWriteableGuestFile(
      uR"(\??\C:\Users\over\Desktop\wtf_input.id0)");
  g_FsHandleTable.MapNonExistingGuestFile(
      uR"(\??\C:\Users\over\Desktop\wtf_input.id1)");
  g_FsHandleTable.MapNonExistingGuestFile(
      uR"(\??\C:\Users\over\Desktop\wtf_input.nam)");
  g_FsHandleTable.MapNonExistingGuestFile(
      uR"(\??\C:\Users\over\Desktop\wtf_input.id2)");

  //
  // Those files are files we want to pretend that they don't exist in the
  // guest.
  //

  const std::vector<std::u16string> NotFounds = {
      uR"(\??\C:\Program Files\IDA Pro 7.5\ida64.int)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\idsnames)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\epoc.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\epoc6.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\epoc9.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\flirt.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\geos.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\linux.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\os2.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\win.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\win7.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\wince.zip)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\loaders\hppacore.idc)",
      uR"(\??\C:\Users\over\AppData\Roaming\Hex-Rays\IDA Pro\proccache64.lst)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\Latin_1.clt)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\dwarf.cfg)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\ids\)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\atrap.cfg)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\hpux.cfg)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\i960.cfg)",
      uR"(\??\C:\Program Files\IDA Pro 7.5\cfg\goodname.cfg)"};

  for (const std::u16string &NotFound : NotFounds) {
    g_FsHandleTable.MapNonExistingGuestFile(NotFound.c_str());
  }

  g_FsHandleTable.SetBlacklistDecisionHandler([](const std::u16string &Path) {
    // \ids\pc\api-ms-win-core-profile-l1-1-0.idt
    // \ids\api-ms-win-core-profile-l1-1-0.idt
    // \sig\pc\vc64seh.sig
    // \til\pc\gnulnx_x64.til
    // 6ba8075c8f243566350f741c7d6e9318089add.debug
    const bool IsIdt = Path.ends_with(u".idt");
    const bool IsIds = Path.ends_with(u".ids");
    const bool IsSig = Path.ends_with(u".sig");
    const bool IsTil = Path.ends_with(u".til");
    const bool IsDebug = Path.ends_with(u".debug");
    const bool Blacklisted = IsIdt || IsIds || IsSig || IsTil || IsDebug;

    if (Blacklisted) {
      return true;
    }

    //
    // The parser can invoke ida64!import_module to have the user select
    // a file that gets imported by the binary currently analyzed. This is
    // fine if the import directory is well formated, when it's not it
    // potentially uses garbage in the file as a path name. Strategy here
    // is to block the access if the path is not ASCII.
    //

    for (const auto &C : Path) {
      if (isascii(C)) {
        continue;
      }

      DebugPrint("Blocking a weird NtOpenFile: {}\n", u16stringToString(Path));
      return true;
    }

    return false;
  });

  return true;
}

set BASE_DIR=C:\Program Files\IDA Pro 7.5
set PLUGINS_DIR=%BASE_DIR%\plugins
set LOADERS_DIR=%BASE_DIR%\loaders
set PROCS_DIR=%BASE_DIR%\procs
set NTSD=C:\Users\over\Desktop\x64\ntsd.exe

REM Remove a bunch of plugins
del "%PLUGINS_DIR%\python.dll"
del "%PLUGINS_DIR%\python64.dll"
[...]
REM Turning on PH
REM 02000000 Enable page heap (full page heap)
reg.exe add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\ida64.exe" /v "GlobalFlag" /t REG_SZ /d "0x2000000" /f
REM This is useful to disable stack-traces
reg.exe add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\ida64.exe" /v "PageHeapFlags" /t REG_SZ /d "0x0" /f

REM History is stored in the registry and so triggers cr3 change (when attaching to Registry process VA)
set IDA_NO_HISTORY=1
REM Set up headless mode and run IDA
set TVHEADLESS=1
REM https://www.hex-rays.com/products/ida/support/idadoc/417.shtml
start /b %NTSD% -d "%BASE_DIR%\ida64.exe" -B wtf_input

REM bp ida64!init_database
REM Bump suspend count: ~0n
REM Detach: qd
REM Find process, set ba e1 on address from kdbg
REM ntsd -pn ida64.exe ; fix suspend count: ~0m
REM should break.

REM Inject the dlls.
inject.exe ida64.exe "%PLUGINS_DIR%"
inject.exe ida64.exe "%LOADERS_DIR%"
inject.exe ida64.exe "%PROCS_DIR%"
inject.exe ida64.exe "%BASE_DIR%\libdwarf.dll"

REM Lock everything
lockmem.exe ida64.exe

REM You can now reattach; and ~0m to bump down the suspend count
%NTSD% -pn ida64.exe

if (!g_Backend->SetBreakpoint(
        "ntdll!NtQueryAttributesFile", [](Backend_t *Backend) {
          // NTSTATUS NtQueryAttributesFile(
          //  _In_  POBJECT_ATTRIBUTES      ObjectAttributes,
          //  _Out_ PFILE_BASIC_INFORMATION FileInformation
          //);
          // ...
          //
          // Ensure that the GuestFileInformation is faulted-in memory.
          //

          if (GuestFileInformation &&
              Backend->PageFaultsMemoryIfNeeded(
                  GuestFileInformation, sizeof(FILE_BASIC_INFORMATION))) {
            return;
          }

wtf.exe run --name hevd --backend whv --state targets\hevd\state --runs=100000 --input targets\hevd\crashes\crash-0xfffff764b91c0000-0x0-0xffffbf84fb10e780-0x2-0x0

class TimerQ_t {
  HANDLE TimerQueue_ = nullptr;
  HANDLE LastTimer_ = nullptr;

  static void CALLBACK AlarmHandler(PVOID, BOOLEAN) {
    reinterpret_cast<WhvBackend_t *>(g_Backend)->CancelRunVirtualProcessor();
  }

public:
  ~TimerQ_t() {
    if (TimerQueue_) {
      DeleteTimerQueueEx(TimerQueue_, nullptr);
    }
  }

  TimerQ_t() = default;
  TimerQ_t(const TimerQ_t &) = delete;
  TimerQ_t &operator=(const TimerQ_t &) = delete;

  void SetTimer(const uint32_t Seconds) {
    if (Seconds == 0) {
      return;
    }

    if (!TimerQueue_) {
      TimerQueue_ = CreateTimerQueue();
      if (!TimerQueue_) {
        fmt::print("CreateTimerQueue failed.\n");
        exit(1);
      }
    }

    if (!CreateTimerQueueTimer(&LastTimer_, TimerQueue_, AlarmHandler,
                                nullptr, Seconds * 1000, Seconds * 1000, 0)) {
      fmt::print("CreateTimerQueueTimer failed.\n");
      exit(1);
    }
  }

  void TerminateLastTimer() {
    DeleteTimerQueueTimer(TimerQueue_, LastTimer_, nullptr);
  }
};

bool WhvBackend_t::PageFaultsMemoryIfNeeded(const Gva_t Gva,
                                            const uint64_t Size) {
  const Gva_t PageToFault = GetFirstVirtualPageToFault(Gva, Size);

  //
  // If we haven't found any GVA to fault-in then we have no job to do so we
  // return.
  //

  if (PageToFault == Gva_t(0xffffffffffffffff)) {
    return false;
  }

  WhvDebugPrint("Inserting page fault for GVA {:#x}\n", PageToFault);

  // cf 'VM-Entry Controls for Event Injection' in Intel 3C
  WHV_REGISTER_VALUE_t Exception;
  Exception->ExceptionEvent.EventPending = 1;
  Exception->ExceptionEvent.EventType = WHvX64PendingEventException;
  Exception->ExceptionEvent.DeliverErrorCode = 1;
  Exception->ExceptionEvent.Vector = WHvX64ExceptionTypePageFault;
  Exception->ExceptionEvent.ErrorCode = ErrorWrite | ErrorUser;
  Exception->ExceptionEvent.ExceptionParameter = PageToFault.U64();

  if (FAILED(SetRegister(WHvRegisterPendingEvent, &Exception))) {
    __debugbreak();
  }

  return true;
}

//
// Make ExGenRandom deterministic.
//
// kd> ub fffff805`3b8287c4 l1
// nt!ExGenRandom+0xe0:
// fffff805`3b8287c0 480fc7f2        rdrand  rdx
const Gva_t ExGenRandom = Gva_t(g_Dbg.GetSymbol("nt!ExGenRandom") + 0xe4);
if (!g_Backend->SetBreakpoint(ExGenRandom, [](Backend_t *Backend) {
      DebugPrint("Hit ExGenRandom!\n");
      Backend->Rdx(Backend->Rdrand());
    })) {
  return false;
}

//
// Add a breakpoint to a GPA.
//

uint8_t *AddBreakpoint(const Gpa_t Gpa) {
  const Gpa_t AlignedGpa = Gpa.Align();
  uint8_t *Page = nullptr;

  //
  // Grab the page if we have it in the cache
  //

  if (Cache_.contains(Gpa.Align())) {
    Page = Cache_.at(AlignedGpa);
  }

  //
  // Or allocate and initialize one!
  //

  else {
    Page = (uint8_t *)aligned_alloc(Page::Size, Page::Size);
    if (Page == nullptr) {
      fmt::print("Failed to call aligned_alloc.\n");
      return nullptr;
    }

    const uint8_t *Virgin =
        Dmp_.GetPhysicalPage(AlignedGpa.U64()) + AlignedGpa.Offset().U64();
    if (Virgin == nullptr) {
      fmt::print(
          "The dump does not have a page backing GPA {:#x}, exiting.\n",
          AlignedGpa);
      return nullptr;
    }

    memcpy(Page, Virgin, Page::Size);
  }

  //
  // Apply the breakpoint.
  //

  const uint64_t Offset = Gpa.Offset().U64();
  Page[Offset] = 0xcc;
  Cache_.emplace(AlignedGpa, Page);

  //
  // And also update the RAM.
  //

  Ram_[Gpa.U64()] = 0xcc;
  return &Page[Offset];
}

//
// Remove a breakpoint from a GPA.
//

void RemoveBreakpoint(const Gpa_t Gpa) {
  const uint8_t *Virgin = GetHvaFromDump(Gpa);
  uint8_t *Cache = GetHvaFromCache(Gpa);

  //
  // Update the RAM.
  //

  Ram_[Gpa.U64()] = *Virgin;

  //
  // Update the cache. We assume that an entry is available in the cache.
  //

  *Cache = *Virgin;
}

//
// Restore a GPA from the cache or from the dump file if no entry is
// available in the cache.
//

const uint8_t *Restore(const Gpa_t Gpa) {
  //
  // Get the HVA for the page we want to restore.
  //

  const uint8_t *SrcHva = GetHva(Gpa);

  //
  // Get the HVA for the page in RAM.
  //

  uint8_t *DstHva = Ram_ + Gpa.Align().U64();

  //
  // It is possible for a GPA to not exist in our cache and in the dump file.
  // For this to make sense, you have to remember that the crash-dump does not
  // contain the whole amount of RAM. In which case, the guest OS can decide
  // to allocate new memory backed by physical pages that were not dumped
  // because not currently used by the OS.
  //
  // When this happens, we simply zero initialize the page as.. this is
  // basically the best we can do. The hope is that if this behavior is not
  // correct, the rest of the execution simply explodes pretty fast.
  //

  if (!SrcHva) {
    memset(DstHva, 0, Page::Size);
  }

  //
  // Otherwise, this is straight forward, we restore the source into the
  // destination. If we had a copy, then that is what we are writing to the
  // destination, and if we didn't have a copy then we are restoring the
  // content from the crash-dump.
  //

  else {
    memcpy(DstHva, SrcHva, Page::Size);
  }

  //
  // Return the HVA to the user in case it needs to know about it.
  //

  return DstHva;
}

HRESULT
WhvBackend_t::OnExitReasonMemoryAccess(
    const WHV_RUN_VP_EXIT_CONTEXT &Exception) {
  const Gpa_t Gpa = Gpa_t(Exception.MemoryAccess.Gpa);
  const bool WriteAccess =
      Exception.MemoryAccess.AccessInfo.AccessType == WHvMemoryAccessWrite;

  if (!WriteAccess) {
    fmt::print("Dont know how to handle this fault, exiting.\n");
    __debugbreak();
    return E_FAIL;
  }

  //
  // Remap the page as writeable.
  //

  const WHV_MAP_GPA_RANGE_FLAGS Flags = WHvMapGpaRangeFlagWrite |
                                        WHvMapGpaRangeFlagRead |
                                        WHvMapGpaRangeFlagExecute;

  const Gpa_t AlignedGpa = Gpa.Align();
  DirtyGpa(AlignedGpa);

  uint8_t *AlignedHva = PhysTranslate(AlignedGpa);
  return MapGpaRange(AlignedHva, AlignedGpa, Page::Size, Flags);
}

HRESULT
WhvBackend_t::TranslateGva(const Gva_t Gva, const WHV_TRANSLATE_GVA_FLAGS,
                           WHV_TRANSLATE_GVA_RESULT &TranslationResult,
                           Gpa_t &Gpa) const {

  //
  // Stole most of the logic from @yrp604's code so thx bro.
  //

  const VIRTUAL_ADDRESS GuestAddress = Gva.U64();
  const MMPTE_HARDWARE Pml4 = GetReg64(WHvX64RegisterCr3);
  const uint64_t Pml4Base = Pml4.PageFrameNumber * Page::Size;
  const Gpa_t Pml4eGpa = Gpa_t(Pml4Base + GuestAddress.Pml4Index * 8);
  const MMPTE_HARDWARE Pml4e = PhysRead8(Pml4eGpa);
  if (!Pml4e.Present) {
    TranslationResult.ResultCode = WHvTranslateGvaResultPageNotPresent;
    return S_OK;
  }

  const uint64_t PdptBase = Pml4e.PageFrameNumber * Page::Size;
  const Gpa_t PdpteGpa = Gpa_t(PdptBase + GuestAddress.PdPtIndex * 8);
  const MMPTE_HARDWARE Pdpte = PhysRead8(PdpteGpa);
  if (!Pdpte.Present) {
    TranslationResult.ResultCode = WHvTranslateGvaResultPageNotPresent;
    return S_OK;
  }

  //
  // huge pages:
  // 7 (PS) - Page size; must be 1 (otherwise, this entry references a page
  // directory; see Table 4-1
  //

  const uint64_t PdBase = Pdpte.PageFrameNumber * Page::Size;
  if (Pdpte.LargePage) {
    TranslationResult.ResultCode = WHvTranslateGvaResultSuccess;
    Gpa = Gpa_t(PdBase + (Gva.U64() & 0x3fff'ffff));
    return S_OK;
  }

  const Gpa_t PdeGpa = Gpa_t(PdBase + GuestAddress.PdIndex * 8);
  const MMPTE_HARDWARE Pde = PhysRead8(PdeGpa);
  if (!Pde.Present) {
    TranslationResult.ResultCode = WHvTranslateGvaResultPageNotPresent;
    return S_OK;
  }

  //
  // large pages:
  // 7 (PS) - Page size; must be 1 (otherwise, this entry references a page
  // table; see Table 4-18
  //

  const uint64_t PtBase = Pde.PageFrameNumber * Page::Size;
  if (Pde.LargePage) {
    TranslationResult.ResultCode = WHvTranslateGvaResultSuccess;
    Gpa = Gpa_t(PtBase + (Gva.U64() & 0x1f'ffff));
    return S_OK;
  }

  const Gpa_t PteGpa = Gpa_t(PtBase + GuestAddress.PtIndex * 8);
  const MMPTE_HARDWARE Pte = PhysRead8(PteGpa);
  if (!Pte.Present) {
    TranslationResult.ResultCode = WHvTranslateGvaResultPageNotPresent;
    return S_OK;
  }

  TranslationResult.ResultCode = WHvTranslateGvaResultSuccess;
  const uint64_t PageBase = Pte.PageFrameNumber * 0x1000;
  Gpa = Gpa_t(PageBase + GuestAddress.Offset);
  return S_OK;
}

//
// Get the size of the shared kvm run structure.
//

VpMmapSize_ = ioctl(Kvm_, KVM_GET_VCPU_MMAP_SIZE, 0);
if (VpMmapSize_ < 0) {
  perror("Could not get the size of the shared memory region.");
  return false;
}

//
// Man says:
//   there is an implicit parameter block that can be obtained by mmap()'ing
//   the vcpu fd at offset 0, with the size given by KVM_GET_VCPU_MMAP_SIZE.
//

Run_ = (struct kvm_run *)mmap(nullptr, VpMmapSize_, PROT_READ | PROT_WRITE,
                              MAP_SHARED, Vp_, 0);
if (Run_ == nullptr) {
  perror("mmap VCPU_MMAP_SIZE");
  return false;
}

void KvmBackend_t::UffdThreadMain() {
  while (!UffdThreadStop_) {

    //
    // Set up the pool fd with the uffd fd.
    //

    struct pollfd PoolFd = {.fd = Uffd_, .events = POLLIN};

    int Res = poll(&PoolFd, 1, 6000);
    if (Res < 0) {

      //
      // Sometimes poll returns -EINTR when we are trying to kick off the CPU
      // out of KVM_RUN.
      //

      if (errno == EINTR) {
        fmt::print("Poll returned EINTR\n");
        continue;
      }

      perror("poll");
      exit(EXIT_FAILURE);
    }

    //
    // This is the timeout, so we loop around to have a chance to check for
    // UffdThreadStop_.
    //

    if (Res == 0) {
      continue;
    }

    //
    // You get the address of the access that triggered the missing page event
    // out of a struct uffd_msg that you read in the thread from the uffd. You
    // can supply as many pages as you want with UFFDIO_COPY or UFFDIO_ZEROPAGE.
    // Keep in mind that unless you used DONTWAKE then the first of any of those
    // IOCTLs wakes up the faulting thread.
    //

    struct uffd_msg UffdMsg;
    Res = read(Uffd_, &UffdMsg, sizeof(UffdMsg));
    if (Res < 0) {
      perror("read");
      exit(EXIT_FAILURE);
    }

    //
    // Let's ensure we are dealing with what we think we are dealing with.
    //

    if (Res != sizeof(UffdMsg) || UffdMsg.event != UFFD_EVENT_PAGEFAULT) {
      fmt::print("The uffdmsg or the type of event we received is unexpected, "
                 "bailing.");
      exit(EXIT_FAILURE);
    }

    //
    // Grab the HVA off the message.
    //

    const uint64_t Hva = UffdMsg.arg.pagefault.address;

    //
    // Compute the GPA from the HVA.
    //

    const Gpa_t Gpa = Gpa_t(Hva - uint64_t(Ram_.Hva()));

    //
    // Page it in.
    //

    RunStats_.UffdPages++;
    const uint8_t *Src = Ram_.GetHvaFromDump(Gpa);
    if (Src != nullptr) {
      const struct uffdio_copy UffdioCopy = {
          .dst = Hva,
          .src = uint64_t(Src),
          .len = Page::Size,
      };

      //
      // The primary ioctl to resolve userfaults is UFFDIO_COPY. That atomically
      // copies a page into the userfault registered range and wakes up the
      // blocked userfaults (unless uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE
      // is set). Other ioctl works similarly to UFFDIO_COPY. They’re atomic as
      // in guaranteeing that nothing can see an half copied page since it’ll
      // keep userfaulting until the copy has finished.
      //

      Res = ioctl(Uffd_, UFFDIO_COPY, &UffdioCopy);
      if (Res < 0) {
        perror("UFFDIO_COPY");
        exit(EXIT_FAILURE);
      }
    } else {
      const struct uffdio_zeropage UffdioZeroPage = {
          .range = {.start = Hva, .len = Page::Size}};

      Res = ioctl(Uffd_, UFFDIO_ZEROPAGE, &UffdioZeroPage);
      if (Res < 0) {
        perror("UFFDIO_ZEROPAGE");
        exit(EXIT_FAILURE);
      }
    }
  }
}

//
// This is to catch the PMI interrupt if performance counters are used to
// bound execution.
//

if (!g_Backend->SetBreakpoint("hal!HalpPerfInterrupt",
                              [](Backend_t *Backend) {
                                CrashDetectionPrint("Perf interrupt\n");
                                Backend->Stop(Timedout_t());
                              })) {
  fmt::print("Could not set a breakpoint on hal!HalpPerfInterrupt, but "
              "carrying on..\n");
}