[PATCH 1/4] include/hw/pci: Introduce a callback to set the downstream mr of PCI hosts

[Jason Chien <jason.chien@sifive.com>]

Many PCI hosts utilize struct PCIIOMMUOps to implement their ATUs, preventing
coexistence with IOMMUs, which need to register struct PCIIOMMUOps as well.

To resolve this, set_downstream_mr() is introduced, allowing IOMMUs to
configure the downstream memory region of the PCI host, enabling both to
coexist.

Signed-off-by: Jason Chien <jason.chien@sifive.com>
---
 include/hw/pci/pci.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index 4002bbeebd..fcf648da19 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -391,6 +391,18 @@ typedef struct PCIIOMMUOps {
      * @devfn: device and function number
      */
     AddressSpace * (*get_address_space)(PCIBus *bus, void *opaque, int devfn);
+    /**
+     * @set_downstream_mr: set the downstream memory region for the PCI host.
+     *
+     * Optional callback that should be implemented if a PCI host registers
+     * this PCIIOMMUOps. It allows an IOMMU to designate its memory region as
+     * the downstream memory region of the PCI host.
+     *
+     * @opaque: the data passed to pci_setup_iommu().
+     *
+     * @mr: the downstream memory region
+     */
+    void (*set_downstream_mr)(void *opaque, MemoryRegion *mr);
     /**
      * @set_iommu_device: attach a HostIOMMUDevice to a vIOMMU
      *
-- 
2.43.2