[LIBXC] Refactor xc_domain_resume() into its own source file.

The idea is that this file is where we will have two implementations
of 'suspend cancellation': one which the guest is aware of (and is
faster) and the other which does more work to avoid requiring guest
modifications.

Signed-off-by: Keir Fraser <keir@xensource.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/tools/libxc/xc_resume.c b/tools/libxc/xc_resume.c
new file mode 100644
index 0000000000..ea9e121054
--- /dev/null
+++ b/tools/libxc/xc_resume.c
@@ -0,0 +1,35 @@
+#include "xc_private.h"
+
+/*
+ * Resume execution of a domain after suspend shutdown.
+ * This can happen in one of two ways:
+ *  1. Resume with special return code.
+ *  2. Reset guest environment so it believes it is resumed in a new
+ *     domain context.
+ * (2) should be used only for guests which cannot handle the special
+ * new return code. (1) is always safe (but slower).
+ * 
+ * XXX Only (2) is implemented below. We need to use (1) by default!
+ */
+int xc_domain_resume(int xc_handle, uint32_t domid)
+{
+    vcpu_guest_context_t ctxt;
+    DECLARE_DOMCTL;
+    int rc;
+
+    /*
+     * Set hypercall return code to indicate that suspend is cancelled
+     * (rather than resuming in a new domain context).
+     */
+#if defined(__i386__) || defined(__x86_64__)
+    if ( (rc = xc_vcpu_getcontext(xc_handle, domid, 0, &ctxt)) != 0 )
+        return rc;
+    ctxt.user_regs.eax = 1;
+    if ( (rc = xc_vcpu_setcontext(xc_handle, domid, 0, &ctxt)) != 0 )
+        return rc;
+#endif
+
+    domctl.cmd = XEN_DOMCTL_resumedomain;
+    domctl.domain = domid;
+    return do_domctl(xc_handle, &domctl);
+}