Re: [PATCH v2 00/17] Add Nested Translation Support for SMMUv3

[Nicolin Chen <nicolinc@nvidia.com>]

On Tue, May 16, 2023 at 11:12:44AM +0800, Zhangfei Gao wrote:

> > > However when debugging hotplug PCI device, it still does not work,
> > > Segmentation fault same as 6.2.
> > >
> > > guest kernel
> > > CONFIG_HOTPLUG_PCI_PCIE=y
> > >
> > > boot guest (this info does not appear in 6.2)
> > > qemu-system-aarch64: -device
> > > vfio-pci,host=0000:76:00.1,bus=pci.1,addr=0x0,id=acc1,iommufd=iommufd0:
> > > Failed to set data -1
> > > qemu-system-aarch64: -device
> > > vfio-pci,host=0000:76:00.1,bus=pci.1,addr=0x0,id=acc1,iommufd=iommufd0:
> > > failed to set device data
> >
> > Hmm.. I wonder what fails the set_dev_data ioctl...
> Simply debug, it is because dev_data.sid=0, causing
> arm_smmu_set_dev_user_data fail

I found that too. The input pci bus number is 1, yet the in
the context of set_dev_data, the pci bus number is 0, which
resulted in a 0-valued sid. I will take another look to get
why.

> > > $ sudo nc -U /tmp/qmpm_1.socket
> > > (qemu) info pci
> > > (qemu) device_del acc1
> > >
> > > guest:
> > > qemu-system-aarch64: IOMMU_IOAS_UNMAP failed: No such file or directory
> > > qemu-system-aarch64: vfio_container_dma_unmap(0xaaaae1fc0380,
> > > 0x8000000000, 0x10000) = -2 (No such file or directory)
> >
> From ex-email reply
> (Eric) In qemu arm virt machine 0x8000000000 matches the PCI MMIO region.
> (Yi) Currently, iommufd kernel part doesn't support mapping device BAR MMIO.
> This is a known gap.

OK.

> > > qemu-system-aarch64: Failed to unset data -1
> > > Segmentation fault (core dumped).  // also happened in 6.2
> >
> > Hmm, would it be possible for you to run the test again by
> > adding the following tracers to your QEMU command?
> >     --trace "iommufd*" \
> >     --trace "smmu*" \
> >     --trace "vfio_*" \
> >     --trace "pci_*"
> >
> 
> Have sent you the log directly, since it is too big.

I have found two missing pieces in the device detach routine.
Applying the following should fix the crash at hotplug path.

----------------------------------------------------------------------------
diff --git a/hw/vfio/container-base.c b/hw/vfio/container-base.c
index 89a256efa999..2344307523cb 100644
--- a/hw/vfio/container-base.c
+++ b/hw/vfio/container-base.c
@@ -151,8 +151,10 @@ void vfio_container_destroy(VFIOContainer *container)
     }

     QLIST_FOREACH_SAFE(giommu, &container->giommu_list, giommu_next, tmp) {
-        memory_region_unregister_iommu_notifier(
-                MEMORY_REGION(giommu->iommu_mr), &giommu->n);
+        if (giommu->n.notifier_flags) {
+            memory_region_unregister_iommu_notifier(
+                    MEMORY_REGION(giommu->iommu_mr), &giommu->n);
+        }
         QLIST_REMOVE(giommu, giommu_next);
         g_free(giommu);
     }
diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index 844c60892db2..35d31480390d 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -652,6 +652,9 @@ found:
      */
     if (QLIST_EMPTY(&container->hwpt_list)) {
         vfio_as_del_container(space, bcontainer);
+        if (bcontainer->nested) {
+            memory_listener_unregister(& bcontainer->prereg_listener);
+        }
     }
     __vfio_device_detach_container(vbasedev, container, &err);
     if (err) {
----------------------------------------------------------------------------

Would you please try your case with it?

Thanks
Nic