[PATCH v12 0/1] toolstack-assisted approach to PVHVM guest kexec

[PATCH v12 0/1] toolstack-assisted approach to PVHVM guest kexec

[Vitaly Kuznetsov]

This is the only not merged patch from the original 'toolstack-assisted
approach to PVHVM guest kexec' series.

Changes since v11:
- Minor description change in xl.cfg.pod.5 [Wei Liu]
- Goto-style error handling in do_domain_soft_reset() [Wei Liu]

Original description of the series:

The list of currently known issues blocking kexec (and why the series is
required) is:
- Bound event channels.
- Registered vcpu_info.
- PIRQ/emuirq mappings.
- shared_info frame after XENMAPSPACE_shared_info operation.
- Active grant mappings.

Previously there were several attempts to solve these issues in different ways:
- Individual 'shutdown' hypercalls (e.g. VCPUOP_reset_vcpu_info) (we agreed
  that one 'reset everything' hypercall is better).
- Try building new domain reassigning old domain's memory (memory reassignment
  turned out being too cumbersome).
- Toolstack-less 'reset everything' (turned out being impossible because there
  is not enough knowledge in the hypervisor, e.g. interdomain channels are
  being set up by the toolstack).

This series is a mix of the previously sent 'toolstack-based' and
'reset everything' series. Here are some key points:
- No new domain is created.
- Domain is asking for soft reset with SCHEDOP_shutdown with
  SHUTDOWN_soft_reset shutdown reason.
- XEN_DOMCTL_soft_reset is being called by the toolstack.
- Device model is being restarted.

With regards to active grants. In this series we restart domain's device model,
remove it from xenstore and introduce it back. The only 'misbehaving' backend
keeping active mapping I currently observe is xenconsoled: currently it has no
interface to disconnect from a domain (it just periodically scans all domains
to determine if any of them are dead). This is not an issue for us because:
- This matches standard domain startup as this grant mapping is being set up by
  the toolstack.
- Guest domain is aware of this special page.
grant_table_warn_active_grants() is required to find possible misbehaving
backends in future.

v11 of the 'toolstack-assisted approach to pvhvm guest kexec' is available here:
http://lists.xenproject.org/archives/html/xen-devel/2015-09/msg00547.html

Vitaly Kuznetsov (1):
  (lib)xl: soft reset support

 docs/man/xl.cfg.pod.5        |   8 +-
 tools/libxl/libxl.c          |  22 ++++-
 tools/libxl/libxl.h          |  15 ++++
 tools/libxl/libxl_create.c   | 196 ++++++++++++++++++++++++++++++++++++++-----
 tools/libxl/libxl_internal.h |   4 +
 tools/libxl/libxl_types.idl  |   2 +
 tools/libxl/xl.h             |   1 +
 tools/libxl/xl_cmdimpl.c     |  25 +++++-
 8 files changed, 246 insertions(+), 27 deletions(-)

-- 
2.4.3

[PATCH v12 1/1] (lib)xl: soft reset support

[Vitaly Kuznetsov]

Use existing create/restore path to perform 'soft reset' for HVM
domains. Tear everything down, e.g. destroy domain's device model,
remove the domain from xenstore, save toolstack record and start
over.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
Changes since v11:
- Minor description change in xl.cfg.pod.5 [Wei Liu]
- Goto-style error handling in do_domain_soft_reset() [Wei Liu]
---
 docs/man/xl.cfg.pod.5        |   8 +-
 tools/libxl/libxl.c          |  22 ++++-
 tools/libxl/libxl.h          |  15 ++++
 tools/libxl/libxl_create.c   | 196 ++++++++++++++++++++++++++++++++++++++-----
 tools/libxl/libxl_internal.h |   4 +
 tools/libxl/libxl_types.idl  |   2 +
 tools/libxl/xl.h             |   1 +
 tools/libxl/xl_cmdimpl.c     |  25 +++++-
 8 files changed, 246 insertions(+), 27 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index db4a163..3496bdf 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -351,6 +351,12 @@ destroy the domain.
 write a "coredump" of the domain to F</var/lib/xen/dump/NAME> and then
 restart the domain.
 
+=item B<soft-reset>
+
+Reset all Xen specific interfaces for the Xen-aware HVM domain allowing
+it to reestablish these interfaces and continue executing the domain. PV
+and non-Xen-aware HVM guests are not supported.
+
 =back
 
 The default for C<on_poweroff> is C<destroy>.
@@ -372,7 +378,7 @@ Action to take if the domain crashes.  Default is C<destroy>.
 =item B<on_soft_reset="ACTION">
 
 Action to take if the domain performs 'soft reset' (e.g. does kexec).
-Default is C<restart>.
+Default is C<soft-reset>.
 
 =back
 
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 4d27891..cb451ff 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1500,6 +1500,7 @@ void libxl__domain_destroy(libxl__egc *egc, libxl__domain_destroy_state *dds)
         dds->stubdom.ao = ao;
         dds->stubdom.domid = stubdomid;
         dds->stubdom.callback = stubdom_destroy_callback;
+        dds->stubdom.soft_reset = false;
         libxl__destroy_domid(egc, &dds->stubdom);
     } else {
         dds->stubdom_finished = 1;
@@ -1508,6 +1509,7 @@ void libxl__domain_destroy(libxl__egc *egc, libxl__domain_destroy_state *dds)
     dds->domain.ao = ao;
     dds->domain.domid = dds->domid;
     dds->domain.callback = domain_destroy_callback;
+    dds->domain.soft_reset = dds->soft_reset;
     libxl__destroy_domid(egc, &dds->domain);
 }
 
@@ -1688,10 +1690,14 @@ static void devices_destroy_cb(libxl__egc *egc,
 
     /* Clean up qemu-save and qemu-resume files. They are
      * intermediate files created by libxc. Unfortunately they
-     * don't fit in existing userdata scheme very well.
+     * don't fit in existing userdata scheme very well. In soft reset
+     * case we need to keep the file.
      */
-    rc = libxl__remove_file(gc, libxl__device_model_savefile(gc, domid));
-    if (rc < 0) goto out;
+    if (!dis->soft_reset) {
+        rc = libxl__remove_file(gc,
+                                libxl__device_model_savefile(gc, domid));
+        if (rc < 0) goto out;
+    }
     rc = libxl__remove_file(gc,
              GCSPRINTF(LIBXL_DEVICE_MODEL_RESTORE_FILE".%u", domid));
     if (rc < 0) goto out;
@@ -1702,7 +1708,15 @@ static void devices_destroy_cb(libxl__egc *egc,
         ctx->xch = xc_interface_open(ctx->lg,0,0);
         if (!ctx->xch) goto badchild;
 
-        rc = xc_domain_destroy(ctx->xch, domid);
+        if (!dis->soft_reset) {
+            rc = xc_domain_destroy(ctx->xch, domid);
+        } else {
+            rc = xc_domain_pause(ctx->xch, domid);
+            if (rc < 0) goto badchild;
+            rc = xc_domain_soft_reset(ctx->xch, domid);
+            if (rc < 0) goto badchild;
+            rc = xc_domain_unpause(ctx->xch, domid);
+        }
         if (rc < 0) goto badchild;
         _exit(0);
 
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 5f9047c..4ee9fbf 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -205,6 +205,13 @@
 #define LIBXL_HAVE_BUILDINFO_ARM_GIC_VERSION 1
 
 /*
+ * LIBXL_HAVE_SOFT_RESET indicates that libxl supports performing
+ * 'soft reset' for domains and there is 'soft_reset' shutdown reason
+ * in enum libxl_shutdown_reason.
+ */
+#define LIBXL_HAVE_SOFT_RESET 1
+
+/*
  * libxl ABI compatibility
  *
  * The only guarantee which libxl makes regarding ABI compatibility
@@ -1132,6 +1139,14 @@ int static inline libxl_domain_create_restore_0x040200(
 
 #endif
 
+int libxl_domain_soft_reset(libxl_ctx *ctx,
+                            libxl_domain_config *d_config,
+                            uint32_t domid,
+                            const libxl_asyncop_how *ao_how,
+                            const libxl_asyncprogress_how
+                            *aop_console_how)
+                            LIBXL_EXTERNAL_CALLERS_ONLY;
+
   /* A progress report will be made via ao_console_how, of type
    * domain_create_console_available, when the domain's primary
    * console is available and can be connected to.
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index f5771da..bf2099b 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -496,8 +496,6 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config *d_config,
     /* convenience aliases */
     libxl_domain_create_info *info = &d_config->c_info;
 
-    assert(!libxl_domid_valid_guest(*domid));
-
     uuid_string = libxl__uuid2string(gc, info->uuid);
     if (!uuid_string) {
         rc = ERROR_NOMEM;
@@ -518,7 +516,6 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config *d_config,
         }
         flags |= XEN_DOMCTL_CDF_hap;
     }
-    *domid = -1;
 
     /* Ultimately, handle is an array of 16 uint8_t, same as uuid */
     libxl_uuid_copy(ctx, (libxl_uuid *)handle, &info->uuid);
@@ -530,13 +527,17 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config *d_config,
         goto out;
     }
 
-    ret = xc_domain_create_config(ctx->xch, info->ssidref,
-                                  handle, flags, domid,
-                                  xc_config);
-    if (ret < 0) {
-        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "domain creation fail");
-        rc = ERROR_FAIL;
-        goto out;
+    /* Valid domid here means we're soft resetting. */
+    if (!libxl_domid_valid_guest(*domid)) {
+        ret = xc_domain_create_config(ctx->xch, info->ssidref,
+                                      handle, flags, domid,
+                                      xc_config);
+        if (ret < 0) {
+            LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
+                             "domain creation fail");
+            rc = ERROR_FAIL;
+            goto out;
+        }
     }
 
     rc = libxl__arch_domain_save_config(gc, d_config, xc_config);
@@ -771,9 +772,8 @@ static void initiate_domain_create(libxl__egc *egc,
     libxl_domain_config *const d_config = dcs->guest_config;
     libxl__domain_build_state *const state = &dcs->build_state;
     const int restore_fd = dcs->restore_fd;
-    memset(&dcs->build_state, 0, sizeof(dcs->build_state));
 
-    domid = 0;
+    domid = dcs->domid_soft_reset;
 
     if (d_config->c_info.ssid_label) {
         char *s = d_config->c_info.ssid_label;
@@ -938,7 +938,7 @@ static void initiate_domain_create(libxl__egc *egc,
             d_config->nics[i].devid = ++last_devid;
     }
 
-    if (restore_fd >= 0) {
+    if (restore_fd >= 0 || dcs->domid_soft_reset != INVALID_DOMID) {
         LOG(DEBUG, "restoring, not running bootloader");
         domcreate_bootloader_done(egc, &dcs->bl, 0);
     } else  {
@@ -1011,7 +1011,7 @@ static void domcreate_bootloader_done(libxl__egc *egc,
     dcs->dmss.dm.callback = domcreate_devmodel_started;
     dcs->dmss.callback = domcreate_devmodel_started;
 
-    if ( restore_fd < 0 ) {
+    if (restore_fd < 0 && dcs->domid_soft_reset == INVALID_DOMID) {
         rc = libxl__domain_build(gc, d_config, domid, state);
         domcreate_rebuild_done(egc, dcs, rc);
         return;
@@ -1031,8 +1031,10 @@ static void domcreate_bootloader_done(libxl__egc *egc,
     dcs->srs.completion_callback = domcreate_stream_done;
     dcs->srs.checkpoint_callback = remus_checkpoint_stream_done;
 
-    libxl__stream_read_start(egc, &dcs->srs);
-    return;
+    if (restore_fd >= 0) {
+        libxl__stream_read_start(egc, &dcs->srs);
+        return;
+    }
 
  out:
     domcreate_stream_done(egc, &dcs->srs, rc);
@@ -1121,9 +1123,12 @@ out:
         libxl__file_reference_unmap(&state->pv_ramdisk);
     }
 
-    esave = errno;
-    libxl_fd_set_nonblock(ctx, fd, 0);
-    errno = esave;
+    /* fd == -1 here means we're doing soft reset. */
+    if (fd != -1) {
+        esave = errno;
+        libxl_fd_set_nonblock(ctx, fd, 0);
+        errno = esave;
+    }
     domcreate_rebuild_done(egc, dcs, ret);
 }
 
@@ -1544,6 +1549,14 @@ typedef struct {
     uint32_t *domid_out;
 } libxl__app_domain_create_state;
 
+typedef struct {
+    libxl__app_domain_create_state cdcs;
+    libxl__domain_destroy_state dds;
+    libxl__domain_suspend_state dss;
+    char *toolstack_buf;
+    uint32_t toolstack_len;
+} libxl__domain_soft_reset_state;
+
 static void domain_create_cb(libxl__egc *egc,
                              libxl__domain_create_state *dcs,
                              int rc, uint32_t domid);
@@ -1572,6 +1585,7 @@ static int do_domain_create(libxl_ctx *ctx, libxl_domain_config *d_config,
         if (rc < 0) goto out_err;
     }
     cdcs->dcs.callback = domain_create_cb;
+    cdcs->dcs.domid_soft_reset = INVALID_DOMID;
     libxl__ao_progress_gethow(&cdcs->dcs.aop_console_how, aop_console_how);
     cdcs->domid_out = domid;
 
@@ -1584,6 +1598,135 @@ static int do_domain_create(libxl_ctx *ctx, libxl_domain_config *d_config,
 
 }
 
+static void domain_soft_reset_cb(libxl__egc *egc,
+                                 libxl__domain_destroy_state *dds,
+                                 int rc)
+{
+    STATE_AO_GC(dds->ao);
+    libxl__domain_soft_reset_state *srs = CONTAINER_OF(dds, *srs, dds);
+    libxl__app_domain_create_state *cdcs = &srs->cdcs;
+    char *savefile, *restorefile;
+
+    if (rc) {
+        LOG(ERROR, "destruction of domain %u failed.", dds->domid);
+        goto error;
+    }
+
+    cdcs->dcs.guest_domid = dds->domid;
+    rc = libxl__restore_emulator_xenstore_data(&cdcs->dcs, srs->toolstack_buf,
+                                               srs->toolstack_len);
+    if (rc) {
+        LOG(ERROR, "failed to restore toolstack record.");
+        goto error;
+    }
+
+    savefile = GCSPRINTF(LIBXL_DEVICE_MODEL_SAVE_FILE".%d", dds->domid);
+    restorefile = GCSPRINTF(LIBXL_DEVICE_MODEL_RESTORE_FILE".%d", dds->domid);
+    rc = rename(savefile, restorefile);
+    if (rc) {
+        LOG(ERROR, "failed to rename dm save file.");
+        goto error;
+    }
+
+    initiate_domain_create(egc, &cdcs->dcs);
+    return;
+
+error:
+    domcreate_complete(egc, &cdcs->dcs, rc);
+}
+
+static int do_domain_soft_reset(libxl_ctx *ctx,
+                                libxl_domain_config *d_config,
+                                uint32_t domid_soft_reset,
+                                const libxl_asyncop_how *ao_how,
+                                const libxl_asyncprogress_how
+                                *aop_console_how)
+{
+    AO_CREATE(ctx, 0, ao_how);
+    libxl__domain_soft_reset_state *srs;
+    libxl__app_domain_create_state *cdcs;
+    libxl__domain_create_state *dcs;
+    libxl__domain_build_state *state;
+    libxl__domain_suspend_state *dss;
+    char *dom_path, *xs_store_mfn, *xs_console_mfn;
+    uint32_t domid_out;
+    int rc;
+
+    GCNEW(srs);
+    cdcs = &srs->cdcs;
+    dcs = &cdcs->dcs;
+    state = &dcs->build_state;
+    dss = &srs->dss;
+
+    srs->cdcs.dcs.ao = ao;
+    srs->cdcs.dcs.guest_config = d_config;
+    libxl_domain_config_init(&srs->cdcs.dcs.guest_config_saved);
+    libxl_domain_config_copy(ctx, &srs->cdcs.dcs.guest_config_saved,
+                             d_config);
+    cdcs->dcs.restore_fd = -1;
+    cdcs->dcs.domid_soft_reset = domid_soft_reset;
+    cdcs->dcs.callback = domain_create_cb;
+    libxl__ao_progress_gethow(&srs->cdcs.dcs.aop_console_how,
+                              aop_console_how);
+    cdcs->domid_out = &domid_out;
+
+    dom_path = libxl__xs_get_dompath(gc, domid_soft_reset);
+    if (!dom_path) {
+        LOG(ERROR, "failed to read domain path");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    xs_store_mfn = xs_read(ctx->xsh, XBT_NULL,
+                           GCSPRINTF("%s/store/ring-ref", dom_path),
+                           NULL);
+    state->store_mfn = xs_store_mfn ? atol(xs_store_mfn): 0;
+    free(xs_store_mfn);
+
+    xs_console_mfn = xs_read(ctx->xsh, XBT_NULL,
+                             GCSPRINTF("%s/console/ring-ref", dom_path),
+                             NULL);
+    state->console_mfn = xs_console_mfn ? atol(xs_console_mfn): 0;
+    free(xs_console_mfn);
+
+    dss->ao = ao;
+    dss->domid = domid_soft_reset;
+    dss->dm_savefile = GCSPRINTF(LIBXL_DEVICE_MODEL_SAVE_FILE".%d",
+                                 domid_soft_reset);
+
+    rc = libxl__save_emulator_xenstore_data(dss, &srs->toolstack_buf,
+                                            &srs->toolstack_len);
+    if (rc) {
+        LOG(ERROR, "failed to save toolstack record.");
+        goto out;
+    }
+
+    rc = libxl__domain_suspend_device_model(gc, dss);
+    if (rc) {
+        LOG(ERROR, "failed to suspend device model.");
+        goto out;
+    }
+
+    /*
+     * Ask all backends to disconnect by removing the domain from
+     * xenstore. On the creation path the domain will be introduced to
+     * xenstore again with probably different store/console/...
+     * channels.
+     */
+    xs_release_domain(ctx->xsh, cdcs->dcs.domid_soft_reset);
+
+    srs->dds.ao = ao;
+    srs->dds.domid = domid_soft_reset;
+    srs->dds.callback = domain_soft_reset_cb;
+    srs->dds.soft_reset = true;
+    libxl__domain_destroy(egc, &srs->dds);
+
+    return AO_INPROGRESS;
+
+ out:
+    return AO_CREATE_FAIL(rc);
+}
+
 static void domain_create_cb(libxl__egc *egc,
                              libxl__domain_create_state *dcs,
                              int rc, uint32_t domid)
@@ -1626,6 +1769,21 @@ int libxl_domain_create_restore(libxl_ctx *ctx, libxl_domain_config *d_config,
                             ao_how, aop_console_how);
 }
 
+int libxl_domain_soft_reset(libxl_ctx *ctx,
+                            libxl_domain_config *d_config,
+                            uint32_t domid,
+                            const libxl_asyncop_how *ao_how,
+                            const libxl_asyncprogress_how
+                            *aop_console_how)
+{
+    libxl_domain_build_info *const info = &d_config->b_info;
+
+    if (info->type != LIBXL_DOMAIN_TYPE_HVM) return ERROR_INVAL;
+
+    return do_domain_soft_reset(ctx, d_config, domid, ao_how,
+                                aop_console_how);
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 5fa55a7..57cbf38 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -111,6 +111,7 @@
 #define STUBDOM_SPECIAL_CONSOLES 3
 #define TAP_DEVICE_SUFFIX "-emu"
 #define DOMID_XS_PATH "domid"
+#define INVALID_DOMID ~0
 
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
 
@@ -3226,6 +3227,7 @@ struct libxl__destroy_domid_state {
     /* private to implementation */
     libxl__devices_remove_state drs;
     libxl__ev_child destroyer;
+    bool soft_reset;
 };
 
 struct libxl__domain_destroy_state {
@@ -3240,6 +3242,7 @@ struct libxl__domain_destroy_state {
     int stubdom_finished;
     libxl__destroy_domid_state domain;
     int domain_finished;
+    bool soft_reset;
 };
 
 /*
@@ -3405,6 +3408,7 @@ struct libxl__domain_create_state {
     int restore_fd, libxc_fd;
     int restore_fdfl; /* original flags of restore_fd */
     libxl_domain_restore_params restore_params;
+    uint32_t domid_soft_reset;
     libxl__domain_create_cb *callback;
     libxl_asyncprogress_how aop_console_how;
     /* private to domain_create */
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 9f6ec00..87d8255 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -138,6 +138,8 @@ libxl_action_on_shutdown = Enumeration("action_on_shutdown", [
 
     (5, "COREDUMP_DESTROY"),
     (6, "COREDUMP_RESTART"),
+
+    (7, "SOFT_RESET"),
     ], init_val = "LIBXL_ACTION_ON_SHUTDOWN_DESTROY")
 
 libxl_trigger = Enumeration("trigger", [
diff --git a/tools/libxl/xl.h b/tools/libxl/xl.h
index 6c19c0d..0021112 100644
--- a/tools/libxl/xl.h
+++ b/tools/libxl/xl.h
@@ -194,6 +194,7 @@ typedef enum {
     DOMAIN_RESTART_NONE = 0,     /* No domain restart */
     DOMAIN_RESTART_NORMAL,       /* Domain should be restarted */
     DOMAIN_RESTART_RENAME,       /* Domain should be renamed and restarted */
+    DOMAIN_RESTART_SOFT_RESET,   /* Soft reset should be performed */
 } domain_restart_type;
 
 extern void printf_info_sexp(int domid, libxl_domain_config *d_config, FILE *fh);
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 2706759..7db08a3 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -133,6 +133,8 @@ static const char *action_on_shutdown_names[] = {
 
     [LIBXL_ACTION_ON_SHUTDOWN_COREDUMP_DESTROY] = "coredump-destroy",
     [LIBXL_ACTION_ON_SHUTDOWN_COREDUMP_RESTART] = "coredump-restart",
+
+    [LIBXL_ACTION_ON_SHUTDOWN_SOFT_RESET] = "soft-reset",
 };
 
 /* Optional data, in order:
@@ -1423,7 +1425,7 @@ static void parse_config_data(const char *config_source,
     }
 
     if (xlu_cfg_get_string (config, "on_soft_reset", &buf, 0))
-        buf = "restart";
+        buf = "soft-reset";
     if (!parse_action_on_shutdown(buf, &d_config->on_soft_reset)) {
         fprintf(stderr, "Unknown on_soft_reset action \"%s\" specified\n", buf);
         exit(1);
@@ -2490,6 +2492,11 @@ static domain_restart_type handle_domain_death(uint32_t *r_domid,
         *r_domid = INVALID_DOMID;
         break;
 
+    case LIBXL_ACTION_ON_SHUTDOWN_SOFT_RESET:
+        reload_domain_config(*r_domid, d_config);
+        restart = DOMAIN_RESTART_SOFT_RESET;
+        break;
+
     case LIBXL_ACTION_ON_SHUTDOWN_COREDUMP_DESTROY:
     case LIBXL_ACTION_ON_SHUTDOWN_COREDUMP_RESTART:
         /* Already handled these above. */
@@ -2666,6 +2673,7 @@ static uint32_t create_domain(struct domain_create *dom_info)
     int restore_fd_to_close = -1;
     const libxl_asyncprogress_how *autoconnect_console_how;
     struct save_file_header hdr;
+    uint32_t domid_soft_reset = INVALID_DOMID;
 
     int restoring = (restore_file || (migrate_fd >= 0));
 
@@ -2880,7 +2888,13 @@ start:
          * restore/migrate-receive it again.
          */
         restoring = 0;
-    }else{
+    } else if (domid_soft_reset != INVALID_DOMID) {
+        /* Do soft reset. */
+        ret = libxl_domain_soft_reset(ctx, &d_config, domid_soft_reset,
+                                      0, autoconnect_console_how);
+        domid = domid_soft_reset;
+        domid_soft_reset = INVALID_DOMID;
+    } else {
         ret = libxl_domain_create_new(ctx, &d_config, &domid,
                                       0, autoconnect_console_how);
     }
@@ -2948,8 +2962,13 @@ start:
                 event->u.domain_shutdown.shutdown_reason,
                 event->u.domain_shutdown.shutdown_reason);
             switch (handle_domain_death(&domid, event, &d_config)) {
+            case DOMAIN_RESTART_SOFT_RESET:
+                domid_soft_reset = domid;
+                domid = INVALID_DOMID;
+                /* fall through */
             case DOMAIN_RESTART_RENAME:
-                if (!preserve_domain(&domid, event, &d_config)) {
+                if (domid_soft_reset == INVALID_DOMID &&
+                    !preserve_domain(&domid, event, &d_config)) {
                     /* If we fail then exit leaving the old domain in place. */
                     ret = -1;
                     goto out;
-- 
2.4.3

Re: [PATCH v12 1/1] (lib)xl: soft reset support

[Wei Liu]

On Mon, Sep 21, 2015 at 11:57:34AM +0200, Vitaly Kuznetsov wrote:
> Use existing create/restore path to perform 'soft reset' for HVM
> domains. Tear everything down, e.g. destroy domain's device model,
> remove the domain from xenstore, save toolstack record and start
> over.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Acked-by: Wei Liu <wei.liu2@citrix.com>

Re: [PATCH v12 1/1] (lib)xl: soft reset support

[Ian Campbell]

On Wed, 2015-09-23 at 14:21 +0100, Wei Liu wrote:
> On Mon, Sep 21, 2015 at 11:57:34AM +0200, Vitaly Kuznetsov wrote:
> > Use existing create/restore path to perform 'soft reset' for HVM
> > domains. Tear everything down, e.g. destroy domain's device model,
> > remove the domain from xenstore, save toolstack record and start
> > over.
> > 
> > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> 
> Acked-by: Wei Liu <wei.liu2@citrix.com>

Applied to staging.