[Qemu-devel] [Bug 1305400] Re: qmp-version of memsave makes a zero filled dump

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

** Changed in: qemu
       Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/1305400

Title:
  qmp-version of memsave makes a zero filled dump

Status in QEMU:
  Expired

Bug description:
  calling the memsave function through hmp and qmp makes a different
  results. it happened because hmp_memsave calls synchronization of cpu,
  but qmp_marshal_input_memsave does not. so virDomainMemoryPeek
  (libvirt api) does not work correctly

  1) hmp:
  void hmp_memsave(Monitor *mon, const QDict *qdict)
  {
      uint32_t size = qdict_get_int(qdict, "size");
      const char *filename = qdict_get_str(qdict, "filename");
      uint64_t addr = qdict_get_int(qdict, "val");
      Error *errp = NULL;

      qmp_memsave(addr, size, filename, true, <<<< monitor_get_cpu_index() >>>, 
&errp);
      hmp_handle_error(mon, &errp);
  }
  int monitor_get_cpu_index(void)
  {
      CPUState *cpu = ENV_GET_CPU(<<< mon_get_cpu >>>());
      return cpu->cpu_index;
  }
  static CPUArchState *mon_get_cpu(void)
  {
      if (!cur_mon->mon_cpu) {
          monitor_set_cpu(0);
      }
      <<< cpu_synchronize_state(cur_mon->mon_cpu); >>>
      return cur_mon->mon_cpu->env_ptr;
  }

  2) qmp
  int qmp_marshal_input_memsave(Monitor *mon, const QDict *qdict, QObject **ret)
  {
      Error *local_err = NULL;
      Error **errp = &local_err;
      QDict *args = (QDict *)qdict;
      QmpInputVisitor *mi;
      QapiDeallocVisitor *md;
      Visitor *v;
      int64_t val;
      int64_t size;
      char * filename = NULL;
      bool has_cpu_index = false;
      int64_t cpu_index;

      mi = qmp_input_visitor_new_strict(QOBJECT(args));
      v = qmp_input_get_visitor(mi);
      visit_type_int(v, &val, "val", errp);
      visit_type_int(v, &size, "size", errp);
      visit_type_str(v, &filename, "filename", errp);
      visit_start_optional(v, &has_cpu_index, "cpu-index", errp);
      if (has_cpu_index) {
          visit_type_int(v, &cpu_index, "cpu-index", errp);
      }
      visit_end_optional(v, errp);
      qmp_input_visitor_cleanup(mi);

      if (error_is_set(errp)) {
          goto out;
      }
      <<< qmp_memsave(val, size, filename, has_cpu_index, cpu_index, errp); >>>

  out:
      md = qapi_dealloc_visitor_new();
      v = qapi_dealloc_get_visitor(md);
      visit_type_int(v, &val, "val", NULL);
      visit_type_int(v, &size, "size", NULL);
      visit_type_str(v, &filename, "filename", NULL);
      visit_start_optional(v, &has_cpu_index, "cpu-index", NULL);
      if (has_cpu_index) {
          visit_type_int(v, &cpu_index, "cpu-index", NULL);
      }
      visit_end_optional(v, NULL);
      qapi_dealloc_visitor_cleanup(md);

      if (local_err) {
          qerror_report_err(local_err);
          error_free(local_err);
          return -1;
      }
      return 0;
  }

  how to reproduce:

  1) run qemu as it makes a libvirtd
  ./qemu-system-x86_64 -name gentoo -machine pc-i440fx-1.7,accel=kvm,usb=off -m 
1024 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 
135b3e47-43ca-bc68-e23b-354a2f62a023 -no-user-config -nodefaults -chardev 
socket,id=charmonitor,path=./gentoo.monitor,server,nowait -mon 
chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot 
menu=off,strict=on -kernel ./bzImage -append root="/dev/vda2 vga=38f" -device 
piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive 
file=./gentoo.img,if=none,id=drive-virtio-disk0,format=raw -device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1
 -drive 
file=./install-amd64-minimal-20140320.iso,if=none,id=drive-ide0-1-0,readonly=on,format=raw
 -device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0,bootindex=2 
-chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 
-vnc 127.0.0.1:0 -device 
qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,bus=pci.0,addr=0x2 
-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 -vnc 127.0.0.1:2 
-monitor stdio

  2) attach to qemu through qmp-shell (taken from qemu sources)
  python ./qmp-shell ./gentoo.monitor

  3) make some commands in sequence
  (qmp-shell) memsave memsave val=-2130706432 size=100 filename=./test01
  (stdio monitor) memsave 0xffffffff81000000 100 ./test02
  (qmp-shell) memsave memsave val=-2130706432 size=100 filename=./test03

  result:
  test01 - zero filled
  test02 - right
  test03 - right

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