Function virtual_memory_test

tests/system_test/virtual_memory_test.cpp:29–231

// VirtualMemorySingleton is defined in virtual_memory.hpp

auto virtual_memory_test() -> bool {
  klog::Info("virtual_memory_test: start");

  auto& vm = VirtualMemorySingleton::instance();

  // Test 1: 创建用户页表
  void* user_page_dir = aligned_alloc(cpu_io::virtual_memory::kPageSize,
                                      cpu_io::virtual_memory::kPageSize);
  EXPECT_TRUE(user_page_dir != nullptr,
              "virtual_memory_test: failed to create user page directory");
  memset(user_page_dir, 0, cpu_io::virtual_memory::kPageSize);
  klog::Info("virtual_memory_test: user page directory created at {}",
             user_page_dir);

  // Test 2: 映射页面
  void* virt_addr = reinterpret_cast<void*>(0x200000);
  void* phys_addr = reinterpret_cast<void*>(0x90000000);

  auto map_result =
      vm.MapPage(user_page_dir, virt_addr, phys_addr,
                 cpu_io::virtual_memory::GetUserPagePermissions());
  EXPECT_TRUE(map_result.has_value(),
              "virtual_memory_test: failed to map page");
  klog::Info("virtual_memory_test: mapped va={} to pa={}", virt_addr,
             phys_addr);

  // Test 3: 获取映射
  auto mapped = vm.GetMapping(user_page_dir, virt_addr);
  EXPECT_TRUE(mapped.has_value(), "virtual_memory_test: failed to get mapping");
  if (mapped) {
    EXPECT_EQ(*mapped, phys_addr,
              "virtual_memory_test: mapping address mismatch");
    klog::Info("virtual_memory_test: verified mapping pa={}", *mapped);
  }

  // Test 4: 映射多个页面
  constexpr size_t kNumPages = 5;
  for (size_t i = 0; i < kNumPages; ++i) {
    void* va = reinterpret_cast<void*>(0x300000 +
                                       i * cpu_io::virtual_memory::kPageSize);
    void* pa = reinterpret_cast<void*>(0x91000000 +
                                       i * cpu_io::virtual_memory::kPageSize);

    auto result = vm.MapPage(user_page_dir, va, pa,
                             cpu_io::virtual_memory::GetUserPagePermissions());
    EXPECT_TRUE(result.has_value(),
                "virtual_memory_test: failed to map multiple pages");
  }
  klog::Info("virtual_memory_test: mapped {} pages", kNumPages);

  // Test 5: 验证多页映射
  for (size_t i = 0; i < kNumPages; ++i) {
    void* va = reinterpret_cast<void*>(0x300000 +
                                       i * cpu_io::virtual_memory::kPageSize);
    void* pa = reinterpret_cast<void*>(0x91000000 +
                                       i * cpu_io::virtual_memory::kPageSize);

    auto m = vm.GetMapping(user_page_dir, va);