bin/guest/vmm/device/virtio_rng_test.cc

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "garnet/bin/guest/vmm/device/test_with_device.h"
#include "garnet/bin/guest/vmm/device/virtio_queue_fake.h"

static constexpr char kVirtioRngUrl[] =
    "fuchsia-pkg://fuchsia.com/virtio_rng#meta/virtio_rng.cmx";
static constexpr uint16_t kQueueSize = 16;

class VirtioRngTest : public TestWithDevice {
 protected:
  VirtioRngTest() : queue_(phys_mem_, PAGE_SIZE * 1, kQueueSize) {}

  void SetUp() override {
    // Launch device process.
    fuchsia::guest::device::StartInfo start_info;
    zx_status_t status = LaunchDevice(kVirtioRngUrl, queue_.end(), &start_info);
    ASSERT_EQ(ZX_OK, status);

    // Start device execution.
    services.ConnectToService(rng_.NewRequest());
    status = rng_->Start(std::move(start_info));
    ASSERT_EQ(ZX_OK, status);

    // Configure device queues.
    queue_.Configure(PAGE_SIZE * 0, PAGE_SIZE);
    status = rng_->ConfigureQueue(0, queue_.size(), queue_.desc(),
                                  queue_.avail(), queue_.used());
    ASSERT_EQ(ZX_OK, status);
  }

  fuchsia::guest::device::VirtioRngSyncPtr rng_;
  VirtioQueueFake queue_;
};

TEST_F(VirtioRngTest, Entropy) {
  const size_t kEntropyLen = 16;
  void *data[8];

  DescriptorChainBuilder builder(queue_);
  for (auto &it : data) {
    builder.AppendWritableDescriptor(&it, kEntropyLen);
  }
  zx_status_t status = builder.Build();
  ASSERT_EQ(ZX_OK, status);

  status = rng_->NotifyQueue(0);
  ASSERT_EQ(ZX_OK, status);
  status = WaitOnInterrupt();
  ASSERT_EQ(ZX_OK, status);

  // Check if any of our requested entropies are the same by inserting them all
  // in a set and ensuring no duplicates. If our entropy source is truly random,
  // then the probability that we legitimately get duplicate entropy data,
  // and hence a spurious test failure, is 8! / 2^128 ~= 1.1*10^-34.
  std::set<std::vector<char>> entropy_set;
  for (auto it : data) {
    char *raw_entropy = static_cast<char *>(it);
    std::vector<char> entropy(&raw_entropy[0], &raw_entropy[kEntropyLen]);
    bool result = entropy_set.insert(std::move(entropy)).second;
    ASSERT_TRUE(result);
  }
}