Re: [RFC PATCH v3 3/5] hw/vfio/ap: store object indicating AP config changed in a queue

[Anthony Krowiak]

On 3/10/25 11:35 AM, Rorie Reyes wrote:

Creates an object indicating that an AP configuration change event
has been received and stores it in a queue. These objects will later
be used to store event information for an AP configuration change
when the CHSC instruction is intercepted.

Signed-off-by: Rorie Reyes <rre...@linux.ibm.com>
---
  hw/vfio/ap.c | 10 ++++++++++
  1 file changed, 10 insertions(+)

diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
index 3614657218..ddab764ab4 100644
--- a/hw/vfio/ap.c
+++ b/hw/vfio/ap.c
@@ -41,6 +41,13 @@ struct VFIOAPDevice {
      EventNotifier cfg_notifier;
  };

+typedef struct APConfigChgEvent {

+    QTAILQ_ENTRY(APConfigChgEvent) next;
+} APConfigChgEvent;
+
+QTAILQ_HEAD(, APConfigChgEvent) cfg_chg_events =
+    QTAILQ_HEAD_INITIALIZER(cfg_chg_events);
+
  OBJECT_DECLARE_SIMPLE_TYPE(VFIOAPDevice, VFIO_AP_DEVICE)

static void vfio_ap_compute_needs_reset(VFIODevice *vdev)

@@ -75,11 +82,14 @@ static void vfio_ap_req_notifier_handler(void *opaque)
  static void vfio_ap_cfg_chg_notifier_handler(void *opaque)
  {
      VFIOAPDevice *vapdev = opaque;
+    APConfigChgEvent *cfg_chg_event = g_new0(APConfigChgEvent, 1);

It doesn't make sense to allocate this before the check below. If the
event_notifier_test_and_clear() fails, you'll have allocated this for no
reason. Allocate cfg_cgh_event prior to inserting it into the queue
below.

if (!event_notifier_test_and_clear(&vapdev->cfg_notifier)) {

          return;
      }

+ QTAILQ_INSERT_TAIL(&cfg_chg_events, cfg_chg_event, next);

+
      css_generate_css_crws(0);

}