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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 #include "host/commands/ivserver/vsocsharedmem.h"
     17 
     18 #include <errno.h>
     19 #include <fcntl.h>
     20 #include <stdio.h>
     21 #include <stdlib.h>
     22 #include <string.h>
     23 #include <sys/eventfd.h>
     24 #include <sys/mman.h>
     25 #include <sys/stat.h>
     26 #include <unistd.h>
     27 #include <algorithm>
     28 #include <tuple>
     29 
     30 #include <glog/logging.h>
     31 
     32 #include "common/vsoc/lib/vsoc_memory.h"
     33 #include "uapi/vsoc_shm.h"
     34 
     35 namespace ivserver {
     36 namespace {
     37 
     38 class VSoCSharedMemoryImpl : public VSoCSharedMemory {
     39  public:
     40   VSoCSharedMemoryImpl(const std::map<std::string, size_t> &name_to_region_idx,
     41                        const std::vector<Region> &regions,
     42                        const std::string &path);
     43 
     44   bool GetEventFdPairForRegion(const std::string &region_name,
     45                                cvd::SharedFD *guest_to_host,
     46                                cvd::SharedFD *host_to_guest) const override;
     47 
     48   const cvd::SharedFD &SharedMemFD() const override;
     49 
     50   const std::vector<Region> &Regions() const override;
     51 
     52  private:
     53   void CreateLayout();
     54 
     55   cvd::SharedFD shared_mem_fd_;
     56   const std::map<std::string, size_t> region_name_to_index_;
     57   const std::vector<Region> region_data_;
     58 
     59   VSoCSharedMemoryImpl(const VSoCSharedMemoryImpl &) = delete;
     60   VSoCSharedMemoryImpl &operator=(const VSoCSharedMemoryImpl &other) = delete;
     61 };
     62 
     63 VSoCSharedMemoryImpl::VSoCSharedMemoryImpl(
     64     const std::map<std::string, size_t> &name_to_region_idx,
     65     const std::vector<Region> &regions, const std::string &path)
     66     : shared_mem_fd_(cvd::SharedFD::Open(path.c_str(), O_RDWR)),
     67       region_name_to_index_{name_to_region_idx},
     68       region_data_{regions} {
     69   LOG_IF(FATAL, !shared_mem_fd_->IsOpen())
     70       << "Error in creating shared_memory file: " << shared_mem_fd_->StrError();
     71 }
     72 
     73 const cvd::SharedFD &VSoCSharedMemoryImpl::SharedMemFD() const {
     74   return shared_mem_fd_;
     75 }
     76 
     77 const std::vector<VSoCSharedMemory::Region> &VSoCSharedMemoryImpl::Regions()
     78     const {
     79   return region_data_;
     80 }
     81 
     82 bool VSoCSharedMemoryImpl::GetEventFdPairForRegion(
     83     const std::string &region_name, cvd::SharedFD *guest_to_host,
     84     cvd::SharedFD *host_to_guest) const {
     85   auto it = region_name_to_index_.find(region_name);
     86   if (it == region_name_to_index_.end()) return false;
     87 
     88   *guest_to_host = region_data_[it->second].host_fd;
     89   *host_to_guest = region_data_[it->second].guest_fd;
     90   return true;
     91 }
     92 
     93 }  // anonymous namespace
     94 
     95 std::unique_ptr<VSoCSharedMemory> VSoCSharedMemory::New(
     96     const std::string &path) {
     97   auto device_layout = vsoc::VSoCMemoryLayout::Get();
     98 
     99   std::map<std::string, size_t> name_to_region_idx;
    100   std::vector<Region> regions;
    101   regions.reserve(device_layout->GetRegions().size());
    102 
    103   for (auto region_spec : device_layout->GetRegions()) {
    104     auto device_name = region_spec->region_name();
    105 
    106     // Create one pair of eventfds for this region. Note that the guest to host
    107     // eventfd is non-blocking, whereas the host to guest eventfd is blocking.
    108     // This is in anticipation of blocking semantics for the host side locks.
    109     auto host_fd = cvd::SharedFD::Event(0, EFD_NONBLOCK);
    110     if (!host_fd->IsOpen()) {
    111       LOG(ERROR) << "Failed to create host eventfd for " << device_name << ": "
    112                  << host_fd->StrError();
    113       return nullptr;
    114     }
    115     auto guest_fd = cvd::SharedFD::Event(0, EFD_NONBLOCK);
    116     if (!guest_fd->IsOpen()) {
    117       LOG(ERROR) << "Failed to create guest eventfd for " << device_name << ": "
    118                  << guest_fd->StrError();
    119       return nullptr;
    120     }
    121 
    122     auto region_idx = regions.size();
    123     name_to_region_idx[device_name] = region_idx;
    124     regions.emplace_back(device_name, host_fd, guest_fd);
    125   }
    126 
    127   return std::unique_ptr<VSoCSharedMemory>(
    128       new VSoCSharedMemoryImpl(name_to_region_idx, regions, path));
    129 }
    130 
    131 }  // namespace ivserver
    132