libxl: add support for migrating HVM guests without a device model

Only some minor libxl changes are needed in order to be able to migrate HVM
guests without a device model, no hypervisor changes are needed.

This change prevents sending the emulator context if the device model
version is set to none.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>

diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index deb3ffa720e580eb320b2a3926063c96acda1acd..47971a96d33dcc865f8dd975069ca9e1fdf1f947 100644 (file)
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1316,6 +1316,9 @@ void libxl__domain_suspend_common_switch_qemu_logdirty
     case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
         domain_suspend_switch_qemu_xen_logdirty(domid, enable, shs);
         break;
+    case LIBXL_DEVICE_MODEL_VERSION_NONE:
+        libxl__xc_domain_saverestore_async_callback_done(egc, shs, 0);
+        break;
     default:
         LOG(ERROR,"logdirty switch failed"
             ", no valid device model version found, abandoning suspend");

diff --git a/tools/libxl/libxl_dom_suspend.c b/tools/libxl/libxl_dom_suspend.c
index 4cc01ad0facc65ded31231a71adcc9f605d2d9f2..3313ad1ce48a97da797f8bb7834cfdd3ca75b753 100644 (file)
--- a/tools/libxl/libxl_dom_suspend.c
+++ b/tools/libxl/libxl_dom_suspend.c
@@ -43,6 +43,8 @@ int libxl__domain_suspend_device_model(libxl__gc *gc,
         if (ret)
             unlink(filename);
         break;
+    case LIBXL_DEVICE_MODEL_VERSION_NONE:
+        break;
     default:
         return ERROR_INVAL;
     }

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 15731a84a34f50e0595f6f6db220decc55b9b2dc..a556a38a422f300fe00a4773b3344691b2f99458 100644 (file)
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -3039,6 +3039,9 @@ struct libxl__stream_write_state {
     libxl__datacopier_state dc;
     sws_record_done_cb record_done_callback;
 
+    /* Cache device model version. */
+    libxl_device_model_version device_model_version;
+
     /* Only used when constructing EMULATOR records. */
     libxl__datacopier_state emu_dc;
     libxl__carefd *emu_carefd;

diff --git a/tools/libxl/libxl_stream_read.c b/tools/libxl/libxl_stream_read.c
index 4ec29da9abe5c15702d82235a01b9257900c2ce8..258dec4c8318b71004cd3801a436b18c361f57d4 100644 (file)
--- a/tools/libxl/libxl_stream_read.c
+++ b/tools/libxl/libxl_stream_read.c
@@ -539,6 +539,14 @@ static bool process_record(libxl__egc *egc,
         break;
 
     case REC_TYPE_EMULATOR_XENSTORE_DATA:
+        if (dcs->guest_config->b_info.device_model_version ==
+            LIBXL_DEVICE_MODEL_VERSION_NONE) {
+            rc = ERROR_FAIL;
+            LOG(ERROR,
+                "Received a xenstore emulator record when none was expected");
+            goto err;
+        }
+
         if (rec->hdr.length < sizeof(libxl__sr_emulator_hdr)) {
             rc = ERROR_FAIL;
             LOG(ERROR,
@@ -560,6 +568,14 @@ static bool process_record(libxl__egc *egc,
         break;
 
     case REC_TYPE_EMULATOR_CONTEXT:
+        if (dcs->guest_config->b_info.device_model_version ==
+            LIBXL_DEVICE_MODEL_VERSION_NONE) {
+            rc = ERROR_FAIL;
+            LOG(ERROR,
+                "Received an emulator context record when none was expected");
+            goto err;
+        }
+
         write_emulator_blob(egc, stream, rec);
         break;
 

diff --git a/tools/libxl/libxl_stream_write.c b/tools/libxl/libxl_stream_write.c
index 52a60d7726fb451761dd6f4187cd2c4afba710ec..80d9208062fc260616c0742854a465dee8190b57 100644 (file)
--- a/tools/libxl/libxl_stream_write.c
+++ b/tools/libxl/libxl_stream_write.c
@@ -167,6 +167,8 @@ static void setup_emulator_write(libxl__egc *egc,
                                  void *body,
                                  sws_record_done_cb cb)
 {
+    assert(stream->emu_sub_hdr.id != EMULATOR_UNKNOWN);
+    assert(stream->device_model_version != LIBXL_DEVICE_MODEL_VERSION_NONE);
     setup_generic_write(egc, stream, what, hdr, emu_hdr, body, cb);
 }
 
@@ -207,6 +209,7 @@ void libxl__stream_write_init(libxl__stream_write_state *stream)
     FILLZERO(stream->emu_rec_hdr);
     FILLZERO(stream->emu_sub_hdr);
     stream->emu_body = NULL;
+    stream->device_model_version = LIBXL_DEVICE_MODEL_VERSION_UNKNOWN;
 }
 
 void libxl__stream_write_start(libxl__egc *egc,
@@ -223,7 +226,9 @@ void libxl__stream_write_start(libxl__egc *egc,
     stream->running = true;
 
     if (dss->type == LIBXL_DOMAIN_TYPE_HVM) {
-        switch (libxl__device_model_version_running(gc, dss->domid)) {
+        stream->device_model_version =
+            libxl__device_model_version_running(gc, dss->domid);
+        switch (stream->device_model_version) {
         case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL:
             stream->emu_sub_hdr.id = EMULATOR_QEMU_TRADITIONAL;
             break;
@@ -232,6 +237,10 @@ void libxl__stream_write_start(libxl__egc *egc,
             stream->emu_sub_hdr.id = EMULATOR_QEMU_UPSTREAM;
             break;
 
+        case LIBXL_DEVICE_MODEL_VERSION_NONE:
+            stream->emu_sub_hdr.id = EMULATOR_UNKNOWN;
+            break;
+
         default:
             rc = ERROR_FAIL;
             LOG(ERROR, "Unknown emulator for HVM domain");
@@ -359,6 +368,11 @@ static void write_emulator_xenstore_record(libxl__egc *egc,
     char *buf = NULL;
     uint32_t len = 0;
 
+    if (stream->device_model_version == LIBXL_DEVICE_MODEL_VERSION_NONE) {
+        emulator_xenstore_record_done(egc, stream);
+        return;
+    }
+
     rc = libxl__save_emulator_xenstore_data(dss, &buf, &len);
     if (rc)
         goto err;
@@ -410,6 +424,11 @@ static void write_emulator_context_record(libxl__egc *egc,
 
     assert(dss->type == LIBXL_DOMAIN_TYPE_HVM);
 
+    if (stream->device_model_version == LIBXL_DEVICE_MODEL_VERSION_NONE) {
+        emulator_context_record_done(egc, stream);
+        return;
+    }
+
     /* Convenience aliases */
     const char *const filename = dss->dm_savefile;