Re: [PATCH v2 02/10] hw/vfio/region: Add vfio_region_setup_with_ops()

[Cédric Le Goater]

On 9/16/26 20:44, mho...@nvidia.com wrote:

From: Manish Honap <mho...@nvidia.com>

A CXL Type-2 device traps its HDM decoder block, so that region needs
custom MemoryRegionOps rather than the pass-through default. Split the
setup body out and let a caller supply the ops; NULL keeps the existing
behaviour.

AI-used-for: code (prototype)
Signed-off-by: Manish Honap <mho...@nvidia.com>
---
  hw/vfio/region.c      | 27 ++++++++++++++++++++++++---
  hw/vfio/vfio-region.h |  3 +++
  2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/hw/vfio/region.c b/hw/vfio/region.c
index 54ad11a6c8..21b54978b5 100644
--- a/hw/vfio/region.c
+++ b/hw/vfio/region.c
@@ -228,8 +228,9 @@ static int vfio_setup_region_sparse_mmaps(VFIORegion 
*region,
      return 0;
  }

-int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,

-                      int index, const char *name, Error **errp)
+static int vfio_region_do_setup(Object *obj, VFIODevice *vbasedev,
+                                VFIORegion *region, int index, const char 
*name,
+                                const MemoryRegionOps *ops, Error **errp)
  {
      struct vfio_region_info *info = NULL;
      int ret;
@@ -249,7 +250,7 @@ int vfio_region_setup(Object *obj, VFIODevice *vbasedev, 
VFIORegion *region,

if (region->size) {

          region->mem = g_new0(MemoryRegion, 1);
-        memory_region_init_io(region->mem, obj, &vfio_region_ops,
+        memory_region_init_io(region->mem, obj, ops,
                                region, name, region->size);

if (!vbasedev->no_mmap &&

@@ -273,6 +274,26 @@ int vfio_region_setup(Object *obj, VFIODevice *vbasedev, 
VFIORegion *region,
      return 0;
  }

+int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,

+                      int index, const char *name, Error **errp)
+{
+    return vfio_region_do_setup(obj, vbasedev, region, index, name,
+                                &vfio_region_ops, errp);
+}
+
+/*
+ * Like vfio_region_setup() but traps the region through @ops instead of the
+ * default pass-through, so a caller can intercept accesses (the CXL HDM
+ * decoder block). A NULL @ops keeps the default.
+ */
+int vfio_region_setup_with_ops(Object *obj, VFIODevice *vbasedev,
+                               VFIORegion *region, int index, const char *name,
+                               const MemoryRegionOps *ops, Error **errp)
+{
+    return vfio_region_do_setup(obj, vbasedev, region, index, name,
+                                ops ? ops : &vfio_region_ops, errp);

if you're calling _with_ops(), you have custom ops, that's whole point.
Passing NULL is a caller bug, no need to have a fall back. Or assert().

Thanks,

C.

+}
+
  static void vfio_subregion_unmap(VFIORegion *region, int index)
  {
      trace_vfio_region_unmap(memory_region_name(&region->mmaps[index].mem),
diff --git a/hw/vfio/vfio-region.h b/hw/vfio/vfio-region.h
index 58b236f113..8d5699013a 100644
--- a/hw/vfio/vfio-region.h
+++ b/hw/vfio/vfio-region.h
@@ -39,6 +39,9 @@ uint64_t vfio_region_read(void *opaque,
                            hwaddr addr, unsigned size);
  int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,
                        int index, const char *name, Error **errp);
+int vfio_region_setup_with_ops(Object *obj, VFIODevice *vbasedev,
+                               VFIORegion *region, int index, const char *name,
+                               const MemoryRegionOps *ops, Error **errp);
  int vfio_region_mmap(VFIORegion *region);
  void vfio_region_mmaps_set_enabled(VFIORegion *region, bool enabled);
  void vfio_region_exit(VFIORegion *region);