On 7/3/25 21:33, Richard Henderson wrote:
On 3/7/25 10:03, Philippe Mathieu-Daudé wrote:
iommufd_builtin() can be used to check at runtime whether
the IOMMUFD feature is built in a qemu-system binary.
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
docs/devel/vfio-iommufd.rst | 2 +-
include/system/iommufd.h | 8 ++++++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/docs/devel/vfio-iommufd.rst b/docs/devel/vfio-iommufd.rst
index 3d1c11f175e..08882094eee 100644
--- a/docs/devel/vfio-iommufd.rst
+++ b/docs/devel/vfio-iommufd.rst
@@ -88,7 +88,7 @@ Step 2: configure QEMU
----------------------
Interactions with the ``/dev/iommu`` are abstracted by a new iommufd
-object (compiled in with the ``CONFIG_IOMMUFD`` option).
+object (which availability can be checked at runtime using
``iommufd_builtin()``).
Any QEMU device (e.g. VFIO device) wishing to use ``/dev/iommu`` must
be linked with an iommufd object. It gets a new optional property
diff --git a/include/system/iommufd.h b/include/system/iommufd.h
index cbab75bfbf6..ce459254025 100644
--- a/include/system/iommufd.h
+++ b/include/system/iommufd.h
@@ -63,4 +63,12 @@ bool
iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,
Error **errp);
#define TYPE_HOST_IOMMU_DEVICE_IOMMUFD TYPE_HOST_IOMMU_DEVICE "-
iommufd"
+
+static inline bool iommufd_builtin(void)
+{
+ bool ambig = false;
+
+ return object_resolve_path_type("", TYPE_IOMMUFD_BACKEND, &ambig)
|| ambig;
+}
+
#endif
Interesting solution.
Actually this isn't appropriate as this checks for an *instance*, while
we only want the *class*.
I'll respin a different approach.
