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RE: [Xen-ia64-devel] A potential issue in allocate_rid_range()


  • To: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
  • From: "Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>
  • Date: Fri, 2 Sep 2005 08:18:32 -0700
  • Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Fri, 02 Sep 2005 15:16:15 +0000
  • List-id: Discussion of the ia64 port of Xen <xen-ia64-devel.lists.xensource.com>
  • Thread-index: AcWvm28RRoInUjMyTGGL87Yq27WpxAANgX6g
  • Thread-topic: [Xen-ia64-devel] A potential issue in allocate_rid_range()

Also a good catch!  I'm not sure when we would have allowed
ridbits > 18, but when we do, this would have been very
hard to find!

Thanks!
Dan 

> -----Original Message-----
> From: Xu, Anthony [mailto:anthony.xu@xxxxxxxxx] 
> Sent: Friday, September 02, 2005 2:51 AM
> To: Magenheimer, Dan (HP Labs Fort Collins)
> Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-ia64-devel] A potential issue in allocate_rid_range()
> 
> Hi Dan,
> 
> n_rid_blocks should be the number of current domain occupying in
> ridblock_owner array.
> See below patch.
> Because currently ridbits of each domain are 18, this bug 
> isn't exposed,
> 
> if ridbits is 19 or bigger, domain can't allocate enough rids.
> 
> diff -r 8799d14bef77 xen/arch/ia64/regionreg.c
> --- a/xen/arch/ia64/regionreg.c Thu Aug 25 22:53:20 2005
> +++ b/xen/arch/ia64/regionreg.c Fri Sep  2 16:24:24 2005
> @@ -116,7 +116,7 @@
>         ridbits = IA64_MIN_IMPL_RID_BITS;
> 
>         // convert to rid_blocks and find one
> -       n_rid_blocks = ridbits - IA64_MIN_IMPL_RID_BITS + 1;
> +       n_rid_blocks = 1<<(ridbits - IA64_MIN_IMPL_RID_BITS) ;
> 
>         // skip over block 0, reserved for "meta-physical 
> mappings (and
> Xen)"
>         for (i = n_rid_blocks; i < MAX_RID_BLOCKS; i += 
> n_rid_blocks) {
> 

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