// Copyright 2017 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#ifndef ZIRCON_KERNEL_ARCH_X86_INCLUDE_ARCH_HYPERVISOR_H_
#define ZIRCON_KERNEL_ARCH_X86_INCLUDE_ARCH_HYPERVISOR_H_

#include <zircon/compiler.h>
#include <zircon/syscalls/hypervisor.h>
#include <zircon/types.h>

#include <arch/x86/apic.h>
#include <arch/x86/interrupts.h>
#include <arch/x86/vmx_state.h>
#include <fbl/ref_ptr.h>
#include <hypervisor/guest_physical_address_space.h>
#include <hypervisor/id_allocator.h>
#include <hypervisor/interrupt_tracker.h>
#include <hypervisor/page.h>
#include <hypervisor/trap_map.h>
#include <kernel/event.h>
#include <kernel/spinlock.h>
#include <kernel/timer.h>
#include <ktl/unique_ptr.h>

struct VmxInfo;

class VmxPage : public hypervisor::Page {
 public:
  zx_status_t Alloc(const VmxInfo& info, uint8_t fill);

 private:
  using hypervisor::Page::Alloc;
};

// Represents a guest within the hypervisor.
class Guest {
 public:
  static zx_status_t Create(ktl::unique_ptr<Guest>* out);
  ~Guest();
  DISALLOW_COPY_ASSIGN_AND_MOVE(Guest);

  zx_status_t SetTrap(uint32_t kind, zx_vaddr_t addr, size_t len, fbl::RefPtr<PortDispatcher> port,
                      uint64_t key);

  hypervisor::GuestPhysicalAddressSpace* AddressSpace() const { return gpas_.get(); }
  hypervisor::TrapMap* Traps() { return &traps_; }
  zx_paddr_t MsrBitmapsAddress() const { return msr_bitmaps_page_.PhysicalAddress(); }

  zx_status_t AllocVpid(uint16_t* vpid);
  zx_status_t FreeVpid(uint16_t vpid);

 private:
  ktl::unique_ptr<hypervisor::GuestPhysicalAddressSpace> gpas_;
  hypervisor::TrapMap traps_;
  VmxPage msr_bitmaps_page_;

  DECLARE_MUTEX(Guest) vcpu_mutex_;
  // TODO(alexlegg): Find a good place for this constant to live (max VCPUs).
  hypervisor::IdAllocator<uint16_t, 64> TA_GUARDED(vcpu_mutex_) vpid_allocator_;

  Guest() = default;
};

// Stores the local APIC state across VM exits.
struct LocalApicState {
  // Timer for APIC timer.
  Timer timer;
  // Tracks pending interrupts.
  hypervisor::InterruptTracker<X86_INT_COUNT> interrupt_tracker;
  // LVT timer configuration
  uint32_t lvt_timer = LVT_MASKED;  // Initial state is masked (Vol 3 Section 10.12.5.1).
  uint32_t lvt_initial_count;
  uint32_t lvt_divide_config;
};

// System time is time since boot time and boot time is some fixed point in the past. This
// structure keeps track of the state required to update system time in guest.
struct pvclock_system_time;
struct PvClockState {
  bool is_stable = false;
  uint32_t version = 0;
  pvclock_system_time* system_time = nullptr;
  hypervisor::GuestPtr guest_ptr;
};

// Represents a virtual CPU within a guest.
class Vcpu {
 public:
  static zx_status_t Create(Guest* guest, zx_vaddr_t entry, ktl::unique_ptr<Vcpu>* out);
  ~Vcpu();
  DISALLOW_COPY_ASSIGN_AND_MOVE(Vcpu);

  zx_status_t Resume(zx_port_packet_t* packet);
  void Interrupt(uint32_t vector, hypervisor::InterruptType type);
  zx_status_t ReadState(zx_vcpu_state_t* vcpu_state) const;
  zx_status_t WriteState(const zx_vcpu_state_t& vcpu_state);
  zx_status_t WriteState(const zx_vcpu_io_t& io_state);

 private:
  Guest* const guest_;
  const uint16_t vpid_;
  Thread* const thread_;
  ktl::atomic<bool> running_;
  LocalApicState local_apic_state_;
  PvClockState pvclock_state_;
  VmxState vmx_state_;
  VmxPage host_msr_page_;
  VmxPage guest_msr_page_;
  VmxPage vmcs_page_;
  ktl::unique_ptr<uint8_t[]> guest_extended_registers_;

  Vcpu(Guest* guest, uint16_t vpid, Thread* thread);

  void MigrateCpu(Thread::MigrateStage stage);
  void SaveGuestExtendedRegisters(uint64_t cr4);
  void RestoreGuestExtendedRegisters(uint64_t cr4);
};

#endif  // ZIRCON_KERNEL_ARCH_X86_INCLUDE_ARCH_HYPERVISOR_H_