We add a convenient way to initialize an device-iotlb notifier.
This is meant to be used by ATS-capable devices.

pci_device_iommu_memory_region_pasid is introduces in this commit and
will be used in several other SVM-related functions exposed in
the PCI API.

Signed-off-by: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
---
 hw/pci/pci.c         | 40 ++++++++++++++++++++++++++++++++++++++++
 include/hw/pci/pci.h | 15 +++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 3fe47d4002..0e14ef4ab2 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2747,6 +2747,46 @@ AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
     return &address_space_memory;
 }
 
+static IOMMUMemoryRegion *pci_device_iommu_memory_region_pasid(PCIDevice *dev,
+                                                               uint32_t pasid)
+{
+    PCIBus *bus;
+    PCIBus *iommu_bus;
+    int devfn;
+
+    /*
+     * This function is for internal use in the module,
+     * we can call it with PCI_NO_PASID
+     */
+    if (!dev->is_master ||
+            ((pasid != PCI_NO_PASID) && !pcie_pasid_enabled(dev))) {
+        return NULL;
+    }
+
+    pci_device_get_iommu_bus_devfn(dev, &bus, &iommu_bus, &devfn);
+    if (iommu_bus && iommu_bus->iommu_ops->get_memory_region_pasid) {
+        return iommu_bus->iommu_ops->get_memory_region_pasid(bus,
+                                 iommu_bus->iommu_opaque, devfn, pasid);
+    }
+    return NULL;
+}
+
+bool pci_iommu_init_iotlb_notifier(PCIDevice *dev, uint32_t pasid,
+                                   IOMMUNotifier *n, IOMMUNotify fn,
+                                   void* opaque)
+{
+    IOMMUMemoryRegion *iommu_mr = pci_device_iommu_memory_region_pasid(dev,
+                                                                        pasid);
+    if (!iommu_mr) {
+        return false;
+    }
+    iommu_notifier_init(n, fn, IOMMU_NOTIFIER_DEVIOTLB_EVENTS, 0, HWADDR_MAX,
+                        memory_region_iommu_attrs_to_index(iommu_mr,
+                                                       MEMTXATTRS_UNSPECIFIED));
+    n->opaque = opaque;
+    return true;
+}
+
 AddressSpace *pci_device_iommu_address_space_pasid(PCIDevice *dev,
                                                    uint32_t pasid)
 {
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index 6c60f7a7c5..2147981423 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -458,6 +458,21 @@ bool pci_device_set_iommu_device(PCIDevice *dev, HostIOMMUDevice *hiod,
                                  Error **errp);
 void pci_device_unset_iommu_device(PCIDevice *dev);
 
+/**
+ * pci_iommu_init_iotlb_notifier: initialize an IOMMU notifier
+ *
+ * This function is used by devices before registering an IOTLB notifier
+ *
+ * @dev: the device
+ * @pasid: the pasid of the address space to watch
+ * @n: the notifier to initialize
+ * @fn: the callback to be installed
+ * @opaque: user pointer that can be used to store a state
+ */
+bool pci_iommu_init_iotlb_notifier(PCIDevice *dev, uint32_t pasid,
+                                   IOMMUNotifier *n, IOMMUNotify fn,
+                                   void* opaque);
+
 /**
  * pci_setup_iommu: Initialize specific IOMMU handlers for a PCIBus
  *
-- 
2.44.0