[Xen-devel] [PATCH RFC v3 09/12] Migration with Local Disks Mirroring: New stream phase type for libxc streams

[Bruno Alvisio <bruno.alvisio@xxxxxxxxx>]

Adapted libxc restore stream. Defined libxc stream phase types:

0. XC_STREAM_PHASE_DEFAULT: This is the stream phase when no local disks are
being mirrored as part of the domain save or restore (=0)

1. XC_STREAM_PHASE_POST_MIRROR_DISKS: This stream phase transfers the virtual
RAM from source to destination. It happens after disks mirroring is completed.

2. XC_STREAM_PHASE_PRE_MIRROR_DISKS: This stream transfers pfns and parameters
necessary to start the QEMU process in the destination. It happens before the
disks mirroring.

The PRE_MIRROR_DISKS phase stream type skips the stream_complete ops to restore
the domain. The restore is performed by the POST_MIRROR_DISKS phase stream that
is executed later in the restore flow. If no local disks are mirrored the
restore is executed by the DEFAULT phase stream type.

Signed-off-by: Bruno Alvisio <bruno.alvisio@xxxxxxxxx>
---
 tools/libxc/xc_sr_common.h        |  1 +
 tools/libxc/xc_sr_restore.c       | 51 ++++++++++++++++++++++-----------------
 tools/libxc/xc_sr_stream_format.h |  5 ++++
 3 files changed, 35 insertions(+), 22 deletions(-)

diff --git a/tools/libxc/xc_sr_common.h b/tools/libxc/xc_sr_common.h
index a145a15..8cf393f 100644
--- a/tools/libxc/xc_sr_common.h
+++ b/tools/libxc/xc_sr_common.h
@@ -177,6 +177,7 @@ struct xc_sr_context
     xc_interface *xch;
     uint32_t domid;
     int fd;
+    int stream_phase;
 
     xc_dominfo_t dominfo;
 
diff --git a/tools/libxc/xc_sr_restore.c b/tools/libxc/xc_sr_restore.c
index 7f74d28..924386c 100644
--- a/tools/libxc/xc_sr_restore.c
+++ b/tools/libxc/xc_sr_restore.c
@@ -736,7 +736,10 @@ static int restore(struct xc_sr_context *ctx)
     struct xc_sr_record rec;
     int rc, saved_rc = 0, saved_errno = 0;
 
-    IPRINTF("Restoring domain");
+    if ( ctx->stream_phase != XC_STREAM_PHASE_PRE_MIRROR_DISKS )
+        IPRINTF("Restoring domain");
+    else
+        IPRINTF("Mirroring disks restoring phase");
 
     rc = setup(ctx);
     if ( rc )
@@ -799,11 +802,16 @@ static int restore(struct xc_sr_context *ctx)
      * With Remus, if we reach here, there must be some error on primary,
      * failover from the last checkpoint state.
      */
-    rc = ctx->restore.ops.stream_complete(ctx);
-    if ( rc )
-        goto err;
+    if ( ctx->stream_phase != XC_STREAM_PHASE_PRE_MIRROR_DISKS )
+    {
+        rc = ctx->restore.ops.stream_complete(ctx);
+        if ( rc )
+            goto err;
 
-    IPRINTF("Restore successful");
+        IPRINTF("Restore successful");
+    } else {
+        IPRINTF("Mirroring disks restore phase successful");
+    }
     goto done;
 
  err:
@@ -837,6 +845,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd, 
uint32_t dom,
         {
             .xch = xch,
             .fd = io_fd,
+            .stream_phase = stream_phase
         };
 
     /* GCC 4.4 (of CentOS 6.x vintage) can' t initialise anonymous unions. */
@@ -890,29 +899,27 @@ int xc_domain_restore(xc_interface *xch, int io_fd, 
uint32_t dom,
     ctx.restore.p2m_size = nr_pfns;
 
     if ( ctx.dominfo.hvm )
-    {
         ctx.restore.ops = restore_ops_x86_hvm;
-        if ( restore(&ctx) )
-            return -1;
-    }
     else
-    {
         ctx.restore.ops = restore_ops_x86_pv;
-        if ( restore(&ctx) )
-            return -1;
-    }
 
-    IPRINTF("XenStore: mfn %#"PRIpfn", dom %d, evt %u",
-            ctx.restore.xenstore_gfn,
-            ctx.restore.xenstore_domid,
-            ctx.restore.xenstore_evtchn);
+    if ( restore(&ctx) )
+        return -1;
+
+    if ( stream_phase != XC_STREAM_PHASE_PRE_MIRROR_DISKS )
+    {
+        IPRINTF("XenStore: mfn %#"PRIpfn", dom %d, evt %u",
+                ctx.restore.xenstore_gfn,
+                ctx.restore.xenstore_domid,
+                ctx.restore.xenstore_evtchn);
 
-    IPRINTF("Console: mfn %#"PRIpfn", dom %d, evt %u",
-            ctx.restore.console_gfn,
-            ctx.restore.console_domid,
-            ctx.restore.console_evtchn);
+        IPRINTF("Console: mfn %#"PRIpfn", dom %d, evt %u",
+                ctx.restore.console_gfn,
+                ctx.restore.console_domid,
+                ctx.restore.console_evtchn);
 
-    *console_gfn = ctx.restore.console_gfn;
+        *console_gfn = ctx.restore.console_gfn;
+    }
     *store_mfn = ctx.restore.xenstore_gfn;
 
     return 0;
diff --git a/tools/libxc/xc_sr_stream_format.h 
b/tools/libxc/xc_sr_stream_format.h
index 15ff1c7..c705da4 100644
--- a/tools/libxc/xc_sr_stream_format.h
+++ b/tools/libxc/xc_sr_stream_format.h
@@ -138,6 +138,11 @@ struct xc_sr_rec_hvm_params
     struct xc_sr_rec_hvm_params_entry param[0];
 };
 
+/* LIBXC stream phase types */
+#define XC_STREAM_PHASE_DEFAULT 0
+#define XC_STREAM_PHASE_POST_MIRROR_DISKS 1
+#define XC_STREAM_PHASE_PRE_MIRROR_DISKS 2
+
 #endif
 /*
  * Local variables:
-- 
2.3.2 (Apple Git-55)


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