libxc/restore: split read/handle qemu info

Split read/handle qemu info. The receiving of qemu info
should be done while we receive the migration stream,
handle_qemu will be called when the stream complete.
Otherwise, it will break Remus because read_record()
won't read qemu info and stream_complete will be called
at failover.

Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

tools/libxc/xc_sr_common.h

@@ -288,6 +288,11 @@ struct xc_sr_context
                     /* HVM context blob. */
                     void *context;
                     size_t contextsz;
+
+#ifdef XG_LIBXL_HVM_COMPAT
+                    uint32_t qlen;
+                    void *qbuf;
+#endif
                 } restore;
             };
         } x86_hvm;

tools/libxc/xc_sr_restore.c

@@ -510,6 +510,9 @@ static int process_record(struct xc_sr_context *ctx, struct xc_sr_record *rec)
     return rc;
 }
 
+#ifdef XG_LIBXL_HVM_COMPAT
+extern int read_qemu(struct xc_sr_context *ctx);
+#endif
 /*
  * Restore a domain.
  */
@@ -546,6 +549,15 @@ static int restore(struct xc_sr_context *ctx)
 
     } while ( rec.type != REC_TYPE_END );
 
+#ifdef XG_LIBXL_HVM_COMPAT
+    if ( ctx->dominfo.hvm )
+    {
+        rc = read_qemu(ctx);
+        if ( rc )
+            goto err;
+    }
+#endif
+
     rc = ctx->restore.ops.stream_complete(ctx);
     if ( rc )
         goto err;

tools/libxc/xc_sr_restore_x86_hvm.c

@@ -94,14 +94,14 @@ static int handle_hvm_params(struct xc_sr_context *ctx,
 }
 
 #ifdef XG_LIBXL_HVM_COMPAT
-static int handle_qemu(struct xc_sr_context *ctx)
+int read_qemu(struct xc_sr_context *ctx);
+int read_qemu(struct xc_sr_context *ctx)
 {
     xc_interface *xch = ctx->xch;
-    char qemusig[21], path[256];
+    char qemusig[21];
     uint32_t qlen;
     void *qbuf = NULL;
     int rc = -1;
-    FILE *fp = NULL;
 
     if ( read_exact(ctx->fd, qemusig, sizeof(qemusig)) )
     {
@@ -137,6 +137,28 @@ static int handle_qemu(struct xc_sr_context *ctx)
         goto out;
     }
 
+    /* With Remus, this could be read many times */
+    if ( ctx->x86_hvm.restore.qbuf )
+        free(ctx->x86_hvm.restore.qbuf);
+    ctx->x86_hvm.restore.qbuf = qbuf;
+    ctx->x86_hvm.restore.qlen = qlen;
+    rc = 0;
+
+out:
+    if (rc)
+        free(qbuf);
+    return rc;
+}
+
+static int handle_qemu(struct xc_sr_context *ctx)
+{
+    xc_interface *xch = ctx->xch;
+    char path[256];
+    uint32_t qlen = ctx->x86_hvm.restore.qlen;
+    void *qbuf = ctx->x86_hvm.restore.qbuf;
+    int rc = -1;
+    FILE *fp = NULL;
+
     sprintf(path, XC_DEVICE_MODEL_RESTORE_FILE".%u", ctx->domid);
     fp = fopen(path, "wb");
     if ( !fp )