On Mon, 2011-05-16 at 09:13 -0600, Alex Williamson wrote:
> On Mon, 2011-05-09 at 15:48 +0100, David Woodhouse wrote:
> > On Thu, 2011-05-05 at 18:13 -0700, Yinghai Lu wrote:
> > > @@ -3252,6 +3252,9 @@ static int device_notifier(struct notifi
> > > return 0;
> > >
> > > if (action == BUS_NOTIFY_UNBOUND_DRIVER && !iommu_pass_through) {
> > > + /* before we remove dev with domain, flush IOTLB */
> > > + flush_unmaps();
> > > +
> > > domain_remove_one_dev_info(domain, pdev);
> > >
> > > if (!(domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE) &&
> >
> > That calls flush_unmaps() without the async_umap_flush_lock held,
> > doesn't it? A few days ago I asked someone else to test this candidate
> > patch for a similar issue:
> >
> > http://david.woodhou.se/flush-unmaps-on-unbind.patch
>
> Copying here:
>
> > diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
> > index d552d2c..7e606d6 100644
> > --- a/drivers/pci/intel-iommu.c
> > +++ b/drivers/pci/intel-iommu.c
> > @@ -3256,8 +3259,10 @@ static int device_notifier(struct notifier_block *nb,
> >
> > if (!(domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE) &&
> > !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY) &&
> > - list_empty(&domain->devices))
> > + list_empty(&domain->devices)) {
> > + flush_unmaps_timeout(0);
> > domain_exit(domain);
> > + }
> > }
> >
> > return 0;
> > @@ -3587,6 +3592,7 @@ static void intel_iommu_domain_destroy(struct iommu_domain *domain)
> > struct dmar_domain *dmar_domain = domain->priv;
> >
> > domain->priv = NULL;
> > + flush_unmaps_timeout(0);
> > vm_domain_exit(dmar_domain);
> > }
>
> David, would it be worthwhile to push the unmaps into the
> {vm_}domain_exit() functions to avoid races like this in the future? I
> can verify the above resolves a panic after unbinding a device from
> snd_hda_intel that I hit recently. Do you plan to push this for .39?
BTW, is this second chunk really needed? VM iommu mappings don't seem
to use the lazy unmap path. Thanks,
Alex
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