Re: [PATCH] libxl: avoid bringing up vcpus already online

[Chao Peng <chao.p.peng@linux.intel.com>]

On Mon, Nov 17, 2014 at 09:41:17AM +0000, Wei Liu wrote:
> On Mon, Nov 17, 2014 at 05:28:58PM +0800, Chao Peng wrote:
> > Avoid sending duplicated qmp commands and eliminate the confusing error
> > messages like "Unable to add CPU: 0, it already exists".
> > 
> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> > ---
> >  tools/libxl/libxl.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> > index f7961f6..d040e5c 100644
> > --- a/tools/libxl/libxl.c
> > +++ b/tools/libxl/libxl.c
> > @@ -5450,7 +5450,7 @@ static int libxl__set_vcpuonline_qmp(libxl__gc *gc, uint32_t domid,
> >          LOGE(ERROR, "getting domain info list");
> >          return ERROR_FAIL;
> >      }
> > -    for (i = 0; i <= info.vcpu_max_id; i++) {
> > +    for (i = info.vcpu_online; i <= info.vcpu_max_id; i++) {
> 
> I don't think this is right. You're making an assumption that vcpu 0 to
> vcpu "info.vcpu_online" are online, which might not be true in hotplug /
> hot-unplug scenario.
> 
You are right. Though the assumption is true right now as QEMU has not
implemented cpu hot-unplug.

The problem is: There is no way to obtain the vcpu online status in xl
as cpu hot-plug/hot-unplug for HVM are all done in QEMU. I guess it's
hard to fix it now. While it's also a minor issue :-)

Chao
> 
> >          if (libxl_bitmap_test(cpumap, i)) {
> >              /* Return value is ignore because it does not tell anything useful
> >               * on the completion of the command.
> > -- 
> > 1.7.9.5
> 
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