[Xen-changelog] [xen-unstable] libxl: do slow resume after failed migration attempt

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1297971617 0
# Node ID 946962830c450eb471db342ead2ca55eee4084db
# Parent  2afa06e1f103f14da7118bd27db8e69f228a05fe
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>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
 tools/libxl/libxl.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -r 2afa06e1f103 -r 946962830c45 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c       Thu Feb 17 19:39:13 2011 +0000
+++ b/tools/libxl/libxl.c       Thu Feb 17 19:40:17 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);

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