Re: [PATCH v3 4/5] intel_iommu: Fix address space unmap

[Peter Xu]

On Fri, Jun 09, 2023 at 03:31:46AM +0000, Duan, Zhenzhong wrote:
> 
> 
> >-----Original Message-----
> >From: Peter Xu <peterx@redhat.com>
> >Sent: Thursday, June 8, 2023 9:48 PM
> >To: Duan, Zhenzhong <zhenzhong.duan@intel.com>
> >Cc: qemu-devel@nongnu.org; mst@redhat.com; jasowang@redhat.com;
> >pbonzini@redhat.com; richard.henderson@linaro.org; eduardo@habkost.net;
> >marcel.apfelbaum@gmail.com; alex.williamson@redhat.com;
> >clg@redhat.com; david@redhat.com; philmd@linaro.org;
> >kwankhede@nvidia.com; cjia@nvidia.com; Liu, Yi L <yi.l.liu@intel.com>; Peng,
> >Chao P <chao.p.peng@intel.com>
> >Subject: Re: [PATCH v3 4/5] intel_iommu: Fix address space unmap
> >
> >On Thu, Jun 08, 2023 at 05:52:30PM +0800, Zhenzhong Duan wrote:
> >> During address space unmap, corresponding IOVA tree entries are also
> >> removed. But DMAMap is set beyond notifier's scope by 1, so in theory
> >> there is possibility to remove a continuous entry above the notifier's
> >> scope but falling in adjacent notifier's scope.
> >
> >This function is only called in "loop over all notifiers" case (or replay() 
> >that just
> >got removed, but even so there'll be only 1 notifier normally iiuc at least 
> >for
> >vt-d), hopefully it means no bug exist (no Fixes needed, no backport needed
> >either), but still worth fixing it up.
> 
> Not two notifiers as vtd-ir splits for vt-d?

The two notifiers will all be attached to the same IOMMU mr, so
IOMMU_NOTIFIER_FOREACH() will loop over them all always?

And this actually shouldn't matter, IMHO, as the IR split has the
0xfeeXXXXX hole only, so when notifying with end=0xfee00000 (comparing to
end=0xfedfffff) it shouldn't make a difference iiuc because there should
have no iova entry at 0xfee00000 anyway in the tree.

-- 
Peter Xu