Re: [Xen-devel] [PATCH]: Xend: Balloon an additional 8MB for QEMU device model

[Chris Lalancette <clalance@xxxxxxxxxx>]

Chris Lalancette wrote:
> All,
>      Attached is a patch to make Xend balloon down an additional 8MB (for the
> Cirrus logic video device) when doing a restore or migrate.  Without this, you
> can run into the following situation:

All,
     Attached is an updated version of the patch.  Dan Berrange correctly points
out that this logic already exists in xend, when an HVM domain is being created;
the logic just wasn't being used in the restore path.  This patch basically
takes the logic from the creation path and pulls it into the restore path, so
things work properly.

Again, this patch is against 3.1.0, but should apply fairly easily to unstable.

Signed-off-by: Chris Lalancette <clalance@xxxxxxxxxx>

--- xen-3.1.0-src/tools/python/xen/xend/XendCheckpoint.py.orig  2007-08-27 
13:37:53.000000000 -0400
+++ xen-3.1.0-src/tools/python/xen/xend/XendCheckpoint.py       2007-08-27 
14:14:19.000000000 -0400
@@ -18,6 +18,7 @@ import xen.util.auxbin
 import xen.lowlevel.xc
 
 import balloon
+import image
 from XendError import XendError, VmError
 from XendLogging import log
 from XendDomainInfo import DEV_MIGRATE_STEP1, DEV_MIGRATE_STEP2
@@ -168,8 +169,6 @@ def restore(xd, fd, paused=False):
     assert store_port
     assert console_port
 
-    nr_pfns = (dominfo.getMemoryTarget() + 3) / 4 
-
     # if hvm, pass mem size to calculate the store_mfn
     is_hvm = dominfo.is_hvm()
     if is_hvm:
@@ -183,18 +182,32 @@ def restore(xd, fd, paused=False):
         pae  = 0
 
     try:
-        shadow = dominfo.info['shadow_memory']
+        restore_image = image.create(dominfo, dominfo.info['image'],
+                                     dominfo.info['device'])
+        memory = restore_image.getRequiredAvailableMemory(
+            dominfo.info['memory'] * 1024)
+        maxmem = restore_image.getRequiredAvailableMemory(
+            dominfo.info['maxmem'] * 1024)
+        shadow = restore_image.getRequiredShadowMemory(
+            dominfo.info['shadow_memory'] * 1024,
+            dominfo.info['maxmem'] * 1024)
+
         log.debug("restore:shadow=0x%x, _static_max=0x%x, _static_min=0x%x, ",
                   dominfo.info['shadow_memory'],
                   dominfo.info['maxmem'],
                   dominfo.info['memory'])
 
-        balloon.free(xc.pages_to_kib(nr_pfns) + shadow * 1024)
+        # Round shadow up to a multiple of a MiB, as shadow_mem_control
+        # takes MiB and we must not round down and end up under-providing.
+        shadow = ((shadow + 1023) / 1024) * 1024
 
-        shadow_cur = xc.shadow_mem_control(dominfo.getDomid(), shadow)
-        dominfo.info['shadow_memory'] = shadow_cur
+        # set memory limit
+        xc.domain_setmaxmem(dominfo.getDomid(), maxmem)
 
-        xc.domain_setmaxmem(dominfo.getDomid(), dominfo.getMemoryMaximum())
+        balloon.free(memory + shadow)
+
+        shadow_cur = xc.shadow_mem_control(dominfo.getDomid(), shadow / 1024)
+        dominfo.info['shadow_memory'] = shadow_cur
 
         cmd = map(str, [xen.util.auxbin.pathTo(XC_RESTORE),
                         fd, dominfo.getDomid(),
@@ -206,7 +219,7 @@ def restore(xd, fd, paused=False):
         forkHelper(cmd, fd, handler.handler, True)
 
         # We don't want to pass this fd to any other children -- we 
-        # might need to recover ths disk space that backs it.
+        # might need to recover the disk space that backs it.
         try:
             flags = fcntl.fcntl(fd, fcntl.F_GETFD)
             flags |= fcntl.FD_CLOEXEC

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