[Xen-devel] [PATCH] libxl: do slow resume after failed migration attempt

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1297856874 0
# Node ID 1728ed4bbec9e82ca13c2639c8e4ef8b4dc231b6
# Parent  aa466613328f5de78fdfc968473cb06e948c1f5d
libxl: do slow resume after failed migration attempt

both of the current callers for libxl_domain_resume are calling after
a migration has failed, one is failure to suspend on the sender and
the other is failure to start on the destination, both leading to a
resume attempt on the sender.

However in the first case, failure to suspend, there is no guarantee
that the guest has made it as far as the suspend hypercall and
therefore the fast resume method, which frobs the hypercall return to
indicate a cancelled suspend, cannot safely be used since it will
corrupt %eax/%rax.

For the second case, failure to start on destination, I don't think it
really matters if the resume is fast or slow.

Therefore always use the slow/uncooperative version of xc_domain_resume from
libxl_domain_resume.

This makes a PV domain which failed to suspend (e.g. because the core
Linux PM infrastructure within the guest didn't allow it) recover
gracefully.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r aa466613328f -r 1728ed4bbec9 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c       Tue Feb 15 13:40:50 2011 +0000
+++ b/tools/libxl/libxl.c       Wed Feb 16 11:47:54 2011 +0000
@@ -226,7 +226,7 @@ int libxl_domain_resume(libxl_ctx *ctx, 
         rc = ERROR_NI;
         goto out;
     }
-    if (xc_domain_resume(ctx->xch, domid, 1)) {
+    if (xc_domain_resume(ctx->xch, domid, 0)) {
         LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, 
                         "xc_domain_resume failed for domain %u", 
                         domid);

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel