Implement PCIIOMMUOPs [set|unset]_iommu_device() callbacks.
In set(), the HostIOMMUDevice handle is stored in a hash
table indexed by PCI BDF. The object will allow to retrieve
information related to the physical IOMMU.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---
v3 -> v4:
- Simply use native HostIOMMUDevice instead of VirtioHostIOMMUDevice

v2 -> v3:
- include host_iommu_device.h in virtio-iommu.h header
- introduce hiod_destroy() and fix UAF in
  virtio_iommu_unset_iommu_device()
---
 include/hw/virtio/virtio-iommu.h |  2 +
 hw/virtio/virtio-iommu.c         | 82 ++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)

diff --git a/include/hw/virtio/virtio-iommu.h b/include/hw/virtio/virtio-iommu.h
index 83a52cc446..bdb3da72d0 100644
--- a/include/hw/virtio/virtio-iommu.h
+++ b/include/hw/virtio/virtio-iommu.h
@@ -25,6 +25,7 @@
 #include "hw/pci/pci.h"
 #include "qom/object.h"
 #include "qapi/qapi-types-virtio.h"
+#include "sysemu/host_iommu_device.h"
 
 #define TYPE_VIRTIO_IOMMU "virtio-iommu-device"
 #define TYPE_VIRTIO_IOMMU_PCI "virtio-iommu-pci"
@@ -57,6 +58,7 @@ struct VirtIOIOMMU {
     struct virtio_iommu_config config;
     uint64_t features;
     GHashTable *as_by_busptr;
+    GHashTable *host_iommu_devices;
     IOMMUPciBus *iommu_pcibus_by_bus_num[PCI_BUS_MAX];
     PCIBus *primary_bus;
     ReservedRegion *prop_resv_regions;
diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c
index 1326c6ec41..16c8ec3ca4 100644
--- a/hw/virtio/virtio-iommu.c
+++ b/hw/virtio/virtio-iommu.c
@@ -69,6 +69,11 @@ typedef struct VirtIOIOMMUMapping {
     uint32_t flags;
 } VirtIOIOMMUMapping;
 
+struct hiod_key {
+    PCIBus *bus;
+    uint8_t devfn;
+};
+
 static inline uint16_t virtio_iommu_get_bdf(IOMMUDevice *dev)
 {
     return PCI_BUILD_BDF(pci_bus_num(dev->bus), dev->devfn);
@@ -462,8 +467,82 @@ static AddressSpace *virtio_iommu_find_add_as(PCIBus *bus, void *opaque,
     return &sdev->as;
 }
 
+static gboolean hiod_equal(gconstpointer v1, gconstpointer v2)
+{
+    const struct hiod_key *key1 = v1;
+    const struct hiod_key *key2 = v2;
+
+    return (key1->bus == key2->bus) && (key1->devfn == key2->devfn);
+}
+
+static guint hiod_hash(gconstpointer v)
+{
+    const struct hiod_key *key = v;
+    guint value = (guint)(uintptr_t)key->bus;
+
+    return (guint)(value << 8 | key->devfn);
+}
+
+static void hiod_destroy(gpointer v)
+{
+    object_unref(v);
+}
+
+static HostIOMMUDevice *
+get_host_iommu_device(VirtIOIOMMU *viommu, PCIBus *bus, int devfn) {
+    struct hiod_key key = {
+        .bus = bus,
+        .devfn = devfn,
+    };
+
+    return g_hash_table_lookup(viommu->host_iommu_devices, &key);
+}
+
+static bool virtio_iommu_set_iommu_device(PCIBus *bus, void *opaque, int devfn,
+                                          HostIOMMUDevice *hiod, Error **errp)
+{
+    VirtIOIOMMU *viommu = opaque;
+    struct hiod_key *new_key;
+
+    assert(hiod);
+
+    if (get_host_iommu_device(viommu, bus, devfn)) {
+        error_setg(errp, "Host IOMMU device already exists");
+        return false;
+    }
+
+    new_key = g_malloc(sizeof(*new_key));
+    new_key->bus = bus;
+    new_key->devfn = devfn;
+
+    object_ref(hiod);
+    g_hash_table_insert(viommu->host_iommu_devices, new_key, hiod);
+
+    return true;
+}
+
+static void
+virtio_iommu_unset_iommu_device(PCIBus *bus, void *opaque, int devfn)
+{
+    VirtIOIOMMU *viommu = opaque;
+    HostIOMMUDevice *hiod;
+    struct hiod_key key = {
+        .bus = bus,
+        .devfn = devfn,
+    };
+
+    hiod = g_hash_table_lookup(viommu->host_iommu_devices, &key);
+    if (!hiod) {
+        return;
+    }
+
+    g_hash_table_remove(viommu->host_iommu_devices, &key);
+}
+
 static const PCIIOMMUOps virtio_iommu_ops = {
     .get_address_space = virtio_iommu_find_add_as,
+    .set_iommu_device = virtio_iommu_set_iommu_device,
+    .unset_iommu_device = virtio_iommu_unset_iommu_device,
 };
 
 static int virtio_iommu_attach(VirtIOIOMMU *s,
@@ -1357,6 +1436,9 @@ static void virtio_iommu_device_realize(DeviceState *dev, Error **errp)
 
     s->as_by_busptr = g_hash_table_new_full(NULL, NULL, NULL, g_free);
 
+    s->host_iommu_devices = g_hash_table_new_full(hiod_hash, hiod_equal,
+                                                  g_free, hiod_destroy);
+
     if (s->primary_bus) {
         pci_setup_iommu(s->primary_bus, &virtio_iommu_ops, s);
     } else {
-- 
2.41.0