I updated the vcpu_to_cpu string creation to include a field separator,

which gets rid of the -1 -> # hack and works for cpus > 9.

I ran into some issues with stale vcpu_to_cpu lists when running the
hotplug subprogram.  I would take a vcpu offline, and then issue the
command to bring it back and the vcpu_to_cpu list would not have changed
to indicate the the vcpu actually went down.  If I injected a xm list -v
(which always showed the correct mapping) then subsequent hotplug
commands would see the state change and fire off the hotplug request.  I
don't know that not sending the event when not changing state saves that
much work so I took the state check out and now just send the hotplug
event directly.

> Also the whole hotplug stuff is still missing interrupt re-routing
> when a vcpu is taken down.  To do this, we need an evtchn operation to
> change the vcpu affinity of a port by changing notify_vcpu_id.

I don't fully understand all of the mappings that are happening, so this
part of the patch might be way off.  In any case, I've added a new
evtchn op to set the notify_vcpu_id field of a channel.  I updated the
HOTPLUG_CPU code to use the new routines when bringing cpus up and down.
When taking down a cpu, I route the IPI irq channels to CPU 0, and when
the cpu comes up, it re-routes the channels back to the awakened CPU.

From: Ryan Harper <ryanh@us.ibm.com>
Signed-off-by: ian@xensource.com

tools/python/xen/xend/XendDomainInfo.py

@@ -423,8 +423,10 @@ class XendDomainInfo:
             sxpr.append(['cpu_time', self.info['cpu_time']/1e9])    
             sxpr.append(['vcpus', self.info['vcpus']])
             sxpr.append(['cpumap', self.info['cpumap']])
-            sxpr.append(['vcpu_to_cpu', ''.join(map(lambda x: str(x),
-                        self.info['vcpu_to_cpu'][0:self.info['vcpus']]))])
+            # build a string, using '|' to seperate items, show only up
+            # to number of vcpus in domain, and trim the trailing '|'
+            sxpr.append(['vcpu_to_cpu', ''.join(map(lambda x: str(x)+'|',
+                        self.info['vcpu_to_cpu'][0:self.info['vcpus']]))[:-1]])
             
         if self.start_time:
             up_time =  time.time() - self.start_time  

tools/python/xen/xm/main.py

@@ -410,8 +410,7 @@ class ProgList(Prog):
         print 'Name              Id  VCPU  CPU  CPUMAP'
         for dom in doms:
             info = server.xend_domain(dom)
-            # XXX this is quite broken for cpu's > 9
-            vcpu_to_cpu = sxp.child_value(info, 'vcpu_to_cpu', '?').replace('-1','#')
+            vcpu_to_cpu = sxp.child_value(info, 'vcpu_to_cpu', '-1').split('|')
             cpumap = sxp.child_value(info, 'cpumap', [])
             mask = ((int(sxp.child_value(info, 'vcpus', '0')))**2) - 1
             count = 0
@@ -420,10 +419,7 @@ class ProgList(Prog):
                 d['name']   = sxp.child_value(info, 'name', '??')
                 d['dom']    = int(sxp.child_value(info, 'id', '-1'))
                 d['vcpu']   = int(count)
-                if cpu == "#":
-                    d['cpu']    = int("-1")
-                else:
-                    d['cpu']    = int(cpu)
+                d['cpu']    = int(cpu)
                 d['cpumap'] = int(cpumap[count])&mask
                 count = count + 1
                 print ("%(name)-16s %(dom)3d  %(vcpu)4d  %(cpu)3d  0x%(cpumap)x" % d)
@@ -593,15 +589,7 @@ domain DOM"""
         state = int(args[3])
         dom = server.xend_domain(name)
         id = sxp.child_value(dom, 'id')
-        vcpu_to_cpu = sxp.child_value(dom, 'vcpu_to_cpu', '-1')
-        # only send state change if states differ 
-        try:
-            # (down going up) or (up going down)
-            if (vcpu_to_cpu[vcpu] == "-1" and state == 1) or \
-               (vcpu_to_cpu[vcpu] != "-1" and state == 0):
-                server.xend_domain_vcpu_hotplug(id, vcpu, state)
-        except IndexError:
-            print "Invalid VCPU(%d)"%(vcpu)
+        server.xend_domain_vcpu_hotplug(id, vcpu, state)
 
 xm.prog(ProgVcpuhotplug)