Re: [Xen-devel] Ping: Re: VMX status report. Xen:24911 & Dom0: d93dc5c4...

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 21 Mar 2012, Jan Beulich wrote:
> >>> On 15.03.12 at 11:12, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> >>>> On 14.03.12 at 07:08, "Ren, Yongjie" <yongjie.ren@xxxxxxxxx> wrote:
> >>>  -----Original Message-----
> >>> From: xen-devel-bounces@xxxxxxxxxxxxx 
> >>> [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of Jan Beulich
> >>> Sent: Tuesday, March 13, 2012 7:34 PM
> >>> To: Zhou, Chao
> >>> Cc: xen-devel
> >>> Subject: Re: [Xen-devel] VMX status report. Xen:24911 & Dom0:
> >>> d93dc5c4...
> >>> 
> >>> >>> On 13.03.12 at 10:18, "Zhou, Chao" <chao.zhou@xxxxxxxxx> wrote:
> >>> > 1. when detaching a VF from hvm guest, "xl dmesg" will show some
> >>> warning
> >>> > information
> >>> >   http://bugzilla.xen.org/bugzilla/show_bug.cgi?id=1809 
> >>> 
> >>> Could you give the qemu-traditional patch below a try (and report
> >>> the resulting "xl dmesg" regardless of whether this eliminates the
> >>> warning)?
> >>> 
> >> Yes, we tried your below patch. The warning still exists.
> >> Attached is the output of 'xl dmesg' after detaching a VF.
> > 
> > Okay, so this apparently is an ordering problem:
> > 
> > unregister_real_device()
> >   -> pt_config_delete()
> >     -> pt_msix_delete() (frees [and fails to clear] ->msix)
> >   -> pt_unregister_regions()
> >     -> _pt_iomem_helper() (with the patch below)
> >       -> has_msix_mapping() (uses ->msix)
> > 
> > As it is obviously necessary to call _pt_iomem_helper() (rather than
> > xc_domain_memory_mapping() directly) from pt_unregister_regions(),
> > it needs to be determined whether
> > - the calls to pt_config_delete() and pt_unregister_regions() can be
> >   swapped, or
> > - the calling of pt_msix_delete() (and for consistency also the freeing
> >   of ->msi) can be moved into or past the call to
> >   pt_unregister_regions(), or
> > - yet something else can be done about this.
> 
> I'd really appreciate some advice here.

It seems to me that pt_unregister_regions and pt_config_delete could be
swapped without unwanted side effects

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