Re: [PATCH] vdpa: do not save failed dma maps in SVQ iova tree

[Eugenio Perez Martin]

On Wed, Aug 3, 2022 at 10:09 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Tue, Aug 2, 2022 at 10:39 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > If a map fails for whatever reason, it must not be saved in the tree.
> > Otherwise, qemu will try to unmap it in cleanup, leaving to more errors.
> >
> > Fixes: 34e3c94eda ("vdpa: Add custom IOTLB translations to SVQ")
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  hw/virtio/vhost-vdpa.c | 20 +++++++++++++-------
> >  1 file changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> > index 3ff9ce3501..e44c23dce5 100644
> > --- a/hw/virtio/vhost-vdpa.c
> > +++ b/hw/virtio/vhost-vdpa.c
> > @@ -176,6 +176,7 @@ static void vhost_vdpa_listener_commit(MemoryListener 
> > *listener)
> >  static void vhost_vdpa_listener_region_add(MemoryListener *listener,
> >                                             MemoryRegionSection *section)
> >  {
> > +    DMAMap mem_region = {};
> >      struct vhost_vdpa *v = container_of(listener, struct vhost_vdpa, 
> > listener);
> >      hwaddr iova;
> >      Int128 llend, llsize;
> > @@ -212,13 +213,13 @@ static void 
> > vhost_vdpa_listener_region_add(MemoryListener *listener,
> >
> >      llsize = int128_sub(llend, int128_make64(iova));
> >      if (v->shadow_vqs_enabled) {
> > -        DMAMap mem_region = {
> > -            .translated_addr = (hwaddr)(uintptr_t)vaddr,
> > -            .size = int128_get64(llsize) - 1,
> > -            .perm = IOMMU_ACCESS_FLAG(true, section->readonly),
> > -        };
>
> Nit: can we keep this part unchanged?
>

We can, but that implies we should look for iova again at fail_map
tag. If you are ok with that I'm fine to perform the search again.

> Thanks
>
> > +        int r;
> >
> > -        int r = vhost_iova_tree_map_alloc(v->iova_tree, &mem_region);
> > +        mem_region.translated_addr = (hwaddr)(uintptr_t)vaddr,
> > +        mem_region.size = int128_get64(llsize) - 1,
> > +        mem_region.perm = IOMMU_ACCESS_FLAG(true, section->readonly),
> > +
> > +        r = vhost_iova_tree_map_alloc(v->iova_tree, &mem_region);
> >          if (unlikely(r != IOVA_OK)) {
> >              error_report("Can't allocate a mapping (%d)", r);
> >              goto fail;
> > @@ -232,11 +233,16 @@ static void 
> > vhost_vdpa_listener_region_add(MemoryListener *listener,
> >                               vaddr, section->readonly);
> >      if (ret) {
> >          error_report("vhost vdpa map fail!");
> > -        goto fail;
> > +        goto fail_map;
> >      }
> >
> >      return;
> >
> > +fail_map:
> > +    if (v->shadow_vqs_enabled) {
> > +        vhost_iova_tree_remove(v->iova_tree, &mem_region);
> > +    }
> > +
> >  fail:
> >      /*
> >       * On the initfn path, store the first error in the container so we
> > --
> > 2.31.1
> >
>