Xen devel - Jul 2012 - [PATCH] libxl: fix bug the number of running vcpu inconsistent with config file

The following patch will fix the bug 1825.
http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1825

When using memcpy to update vcpu_online, the high bits of vcpu_online 
may unmodified if the size of avail_vcpus less than vcpu_online. So we
need to clear it before the memory copying.

Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>

diff -r 4a28c496acbf tools/libxl/libxl_dom.c
--- a/tools/libxl/libxl_dom.c   Mon Jul 23 17:58:33 2012 +0100
+++ b/tools/libxl/libxl_dom.c   Tue Jul 24 15:41:33 2012 +0800
@@ -357,6 +357,7 @@ static int hvm_build_set_params(xc_inter
     va_hvm = (struct hvm_info_table *)(va_map + HVM_INFO_OFFSET);
     va_hvm->apic_mode = libxl_defbool_val(info->u.hvm.apic);
     va_hvm->nr_vcpus = info->max_vcpus;
+    memset(va_hvm->vcpu_online, 0, sizeof(va_hvm->vcpu_online));
     memcpy(va_hvm->vcpu_online, info->avail_vcpus.map,
info->avail_vcpus.size);
     for (i = 0, sum = 0; i < va_hvm->length; i++)
         sum += ((uint8_t *) va_hvm)[i];

Best regards,
Yang

On Tue, 2012-07-24 at 09:22 +0100, Zhang, Yang Z wrote:
> The following patch will fix the bug 1825.
http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1825
> 
> When using memcpy to update vcpu_online, the high bits of vcpu_online 
> may unmodified if the size of avail_vcpus less than vcpu_online. So we
> need to clear it before the memory copying.
> 
> Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
We probably ought to zero the whole struct but this change is correct in
its own right:

Acked-by: Ian Campbell <ian.campbelL@citrix.com>

Thanks!
> 
> diff -r 4a28c496acbf tools/libxl/libxl_dom.c
> --- a/tools/libxl/libxl_dom.c   Mon Jul 23 17:58:33 2012 +0100
> +++ b/tools/libxl/libxl_dom.c   Tue Jul 24 15:41:33 2012 +0800
> @@ -357,6 +357,7 @@ static int hvm_build_set_params(xc_inter
>      va_hvm = (struct hvm_info_table *)(va_map + HVM_INFO_OFFSET);
>      va_hvm->apic_mode = libxl_defbool_val(info->u.hvm.apic);
>      va_hvm->nr_vcpus = info->max_vcpus;
> +    memset(va_hvm->vcpu_online, 0, sizeof(va_hvm->vcpu_online));
>      memcpy(va_hvm->vcpu_online, info->avail_vcpus.map,
info->avail_vcpus.size);
>      for (i = 0, sum = 0; i < va_hvm->length; i++)
>          sum += ((uint8_t *) va_hvm)[i];
> 
> Best regards,
> Yang

On Tue, 2012-07-24 at 10:04 +0100, Ian Campbell wrote:
> On Tue, 2012-07-24 at 09:22 +0100, Zhang, Yang Z wrote:
> > The following patch will fix the bug 1825.
http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1825
> > 
> > When using memcpy to update vcpu_online, the high bits of vcpu_online 
> > may unmodified if the size of avail_vcpus less than vcpu_online. So we
> > need to clear it before the memory copying.
> > 
> > Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
> 
> We probably ought to zero the whole struct but this change is correct in
> its own right:
> 
> Acked-by: Ian Campbell <ian.campbelL@citrix.com>
And now applied, thanks.

Ian.