[Qemu-devel] [RFC PATCH v3 08/18] spapr_iommu: Implement free_table() helper

[Alexey Kardashevskiy <aik@ozlabs.ru>]

Every sPAPRTCETable object holds an IOMMU memory region which holds
a referenced to the sPAPRTCETable instance. So if we want to free
an sPAPRTCETable instance, calling object_unref() will not be enough
as embedded memory region will hold the reference and we need to break
the loop.

This adds a spapr_tce_free_table() helper which destroys the embedded
memory region and then calls object_unref() on the sPAPRTCETable instance
which will succeed now. The helper adds a new child under unique name
derived from LIOBN.

As we are here, fix spapr_tce_new_table() callers.
At the moment spapr_tce_new_table() references sPAPRTCETable twice -
once in object_new() and second time in object_property_add_child().
The callers of spapr_tce_new_table() should take care of correct
referencing.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 hw/ppc/spapr_iommu.c    | 10 +++++++++-
 hw/ppc/spapr_pci.c      |  2 ++
 hw/ppc/spapr_pci_vfio.c |  2 ++
 include/hw/ppc/spapr.h  |  1 +
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
index a789ce1..bde4c1c 100644
--- a/hw/ppc/spapr_iommu.c
+++ b/hw/ppc/spapr_iommu.c
@@ -147,6 +147,7 @@ sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
                                    bool vfio_accel)
 {
     sPAPRTCETable *tcet;
+    char buf[32];
 
     if (spapr_tce_find_by_liobn(liobn)) {
         fprintf(stderr, "Attempted to create TCE table with duplicate"
@@ -165,13 +166,20 @@ sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
     tcet->nb_table = nb_table;
     tcet->vfio_accel = vfio_accel;
 
-    object_property_add_child(OBJECT(owner), "tce-table", OBJECT(tcet), NULL);
+    snprintf(buf, sizeof(buf) - 1, "tce-table-%08X", tcet->liobn);
+    object_property_add_child(OBJECT(owner), buf, OBJECT(tcet), NULL);
 
     object_property_set_bool(OBJECT(tcet), true, "realized", NULL);
 
     return tcet;
 }
 
+void spapr_tce_free_table(sPAPRTCETable *tcet)
+{
+    object_unparent(OBJECT(&tcet->iommu));
+    object_unparent(OBJECT(tcet));
+}
+
 static void spapr_tce_table_finalize(Object *obj)
 {
     sPAPRTCETable *tcet = SPAPR_TCE_TABLE(obj);
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 727d1fe..ea4b1bb 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -649,6 +649,8 @@ static void spapr_phb_finish_realize(sPAPRPHBState *sphb, Error **errp)
     /* Register default 32bit DMA window */
     memory_region_add_subregion(&sphb->iommu_root, 0,
                                 spapr_tce_get_iommu(tcet));
+
+    object_unref(OBJECT(tcet));
 }
 
 static int spapr_phb_children_reset(Object *child, void *opaque)
diff --git a/hw/ppc/spapr_pci_vfio.c b/hw/ppc/spapr_pci_vfio.c
index d3bddf2..51b4314 100644
--- a/hw/ppc/spapr_pci_vfio.c
+++ b/hw/ppc/spapr_pci_vfio.c
@@ -69,6 +69,8 @@ static void spapr_phb_vfio_finish_realize(sPAPRPHBState *sphb, Error **errp)
     /* Register default 32bit DMA window */
     memory_region_add_subregion(&sphb->iommu_root, tcet->bus_offset,
                                 spapr_tce_get_iommu(tcet));
+
+    object_unref(OBJECT(tcet));
 }
 
 static void spapr_phb_vfio_reset(DeviceState *qdev)
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index f3911a0..5a2a49f 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -475,6 +475,7 @@ sPAPRTCETable *spapr_tce_new_table(DeviceState *owner, uint32_t liobn,
                                    uint32_t page_shift,
                                    uint32_t nb_table,
                                    bool vfio_accel);
+void spapr_tce_free_table(sPAPRTCETable *tcet);
 MemoryRegion *spapr_tce_get_iommu(sPAPRTCETable *tcet);
 void spapr_tce_set_bypass(sPAPRTCETable *tcet, bool bypass);
 int spapr_dma_dt(void *fdt, int node_off, const char *propname,
-- 
2.0.0