Re: [PATCH V5 23/38] backends/iommufd: change process ioctl

[Cédric Le Goater]

On 6/10/25 17:39, Steve Sistare wrote:

Define the change process ioctl

Signed-off-by: Steve Sistare <steven.sist...@oracle.com>

Reviewed-by: Cédric Le Goater <c...@redhat.com>

Thanks,

C.

---
  include/system/iommufd.h |  3 +++
  backends/iommufd.c       | 24 ++++++++++++++++++++++++
  backends/trace-events    |  1 +
  3 files changed, 28 insertions(+)

diff --git a/include/system/iommufd.h b/include/system/iommufd.h
index 2d24d93..db5f2c7 100644
--- a/include/system/iommufd.h
+++ b/include/system/iommufd.h
@@ -69,6 +69,9 @@ bool iommufd_backend_invalidate_cache(IOMMUFDBackend *be, 
uint32_t id,
                                        uint32_t *entry_num, void *data,
                                        Error **errp);

+bool iommufd_change_process_capable(IOMMUFDBackend *be);

+bool iommufd_change_process(IOMMUFDBackend *be, Error **errp);
+
  #define TYPE_HOST_IOMMU_DEVICE_IOMMUFD TYPE_HOST_IOMMU_DEVICE "-iommufd"
  OBJECT_DECLARE_TYPE(HostIOMMUDeviceIOMMUFD, HostIOMMUDeviceIOMMUFDClass,
                      HOST_IOMMU_DEVICE_IOMMUFD)
diff --git a/backends/iommufd.c b/backends/iommufd.c
index 3a2ecc7..87f81a0 100644
--- a/backends/iommufd.c
+++ b/backends/iommufd.c
@@ -73,6 +73,30 @@ static void iommufd_backend_class_init(ObjectClass *oc, 
const void *data)
      object_class_property_add_str(oc, "fd", NULL, iommufd_backend_set_fd);
  }

+bool iommufd_change_process_capable(IOMMUFDBackend *be)

+{
+    struct iommu_ioas_change_process args = {.size = sizeof(args)};
+
+    /*
+     * Call IOMMU_IOAS_CHANGE_PROCESS to verify it is a recognized ioctl.
+     * This is a no-op if the process has not changed since DMA was mapped.
+     */
+    return !ioctl(be->fd, IOMMU_IOAS_CHANGE_PROCESS, &args);
+}
+
+bool iommufd_change_process(IOMMUFDBackend *be, Error **errp)
+{
+    struct iommu_ioas_change_process args = {.size = sizeof(args)};
+    bool ret = !ioctl(be->fd, IOMMU_IOAS_CHANGE_PROCESS, &args);
+
+    if (!ret) {
+        error_setg_errno(errp, errno, "IOMMU_IOAS_CHANGE_PROCESS fd %d failed",
+                         be->fd);
+    }
+    trace_iommufd_change_process(be->fd, ret);
+    return ret;
+}
+
  bool iommufd_backend_connect(IOMMUFDBackend *be, Error **errp)
  {
      int fd;
diff --git a/backends/trace-events b/backends/trace-events
index e5f3e70..56132d3 100644
--- a/backends/trace-events
+++ b/backends/trace-events
@@ -7,6 +7,7 @@ dbus_vmstate_loading(const char *id) "id: %s"
  dbus_vmstate_saving(const char *id) "id: %s"

# iommufd.c

+iommufd_change_process(int fd, bool ret) "fd=%d (%d)"
  iommufd_backend_connect(int fd, bool owned, uint32_t users) "fd=%d owned=%d 
users=%d"
  iommufd_backend_disconnect(int fd, uint32_t users) "fd=%d users=%d"
  iommu_backend_set_fd(int fd) "pre-opened /dev/iommu fd=%d"