[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v8 21/21] libxl: add support for migrating HVM guests without a device model
El 11/11/15 a les 18.14, Andrew Cooper ha escrit: > On 06/11/15 16:05, Roger Pau Monne wrote: >> diff --git a/tools/libxl/libxl_stream_write.c >> b/tools/libxl/libxl_stream_write.c >> index 52a60d7..0a6eaf9 100644 >> --- a/tools/libxl/libxl_stream_write.c >> +++ b/tools/libxl/libxl_stream_write.c >> @@ -232,6 +232,9 @@ void libxl__stream_write_start(libxl__egc *egc, >> stream->emu_sub_hdr.id = EMULATOR_QEMU_UPSTREAM; >> break; >> >> + case LIBXL_DEVICE_MODEL_VERSION_NONE: >> + break; >> + > > This (in principle) leaves stream->emu_sub_hdr.id uninitialised > (although its value will be zero because of libxl__stream_write_init()). > > I would be tempted to (ab)use EMULATOR_UNKNOWN here and have > setup_emulator_write() assert id != UNKNOWN, to catch calls which slip > through the cracks. This seems fine to me and I've implemented it. > >> default: >> rc = ERROR_FAIL; >> LOG(ERROR, "Unknown emulator for HVM domain"); >> @@ -359,6 +362,12 @@ static void write_emulator_xenstore_record(libxl__egc >> *egc, >> char *buf = NULL; >> uint32_t len = 0; >> >> + if (libxl__device_model_version_running(gc, dss->domid) == >> + LIBXL_DEVICE_MODEL_VERSION_NONE) { >> + emulator_xenstore_record_done(egc, stream); >> + return; >> + } >> + > > libxl__device_model_version_running() performs a xenstore action, which > is a steep overhead for constant information. > > It would be better to introduce a new field in libxl__stream_write_state > and cache libxl__device_model_version_running() once in > libxl__stream_write_start(). You can then also use that for an > assertion in setup_emulator_write() Right, so I've ended up adding two asserts in setup_emulator_write: assert(stream->emu_sub_hdr.id != EMULATOR_UNKNOWN); assert(stream->device_model_version != LIBXL_DEVICE_MODEL_VERSION_NONE); Roger. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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