Re: [RFC PATCH v2 2/5] hw/vfio/ap: notification handler for AP config changed event

[Anthony Krowiak]

On 2/4/25 12:07 PM, Rorie Reyes wrote:

Register an event notifier handler to process AP configuration
change events by queuing the event and generating a CRW to let
the guest know its AP configuration has changed

Signed-off-by: Rorie Reyes <rre...@linux.ibm.com>
---
  hw/vfio/ap.c | 29 +++++++++++++++++++++++++++++
  1 file changed, 29 insertions(+)

diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
index 30b08ad375..a2b3735349 100644
--- a/hw/vfio/ap.c
+++ b/hw/vfio/ap.c
@@ -18,6 +18,7 @@
  #include "hw/vfio/vfio-common.h"
  #include "system/iommufd.h"
  #include "hw/s390x/ap-device.h"
+#include "hw/s390x/css.h"
  #include "qemu/error-report.h"
  #include "qemu/event_notifier.h"
  #include "qemu/main-loop.h"
@@ -37,6 +38,7 @@ struct VFIOAPDevice {
      APDevice apdev;
      VFIODevice vdev;
      EventNotifier req_notifier;
+    EventNotifier cfg_notifier;
  };

OBJECT_DECLARE_SIMPLE_TYPE(VFIOAPDevice, VFIO_AP_DEVICE)

@@ -70,6 +72,16 @@ static void vfio_ap_req_notifier_handler(void *opaque)
      }
  }

+static void vfio_ap_cfg_chg_notifier_handler(void *opaque)

+{
+    VFIOAPDevice *vapdev = opaque;
+
+    if (!event_notifier_test_and_clear(&vapdev->cfg_notifier)) {
+        css_generate_css_crws(0);

In patch 3/5, you move the css_generate_css_crws() function outside
of this if block and replace it with a return here. That is the right thing
to do, but you should do it here in this patch.

+    }
+
+}
+
  static bool vfio_ap_register_irq_notifier(VFIOAPDevice *vapdev,
                                            unsigned int irq, Error **errp)
  {
@@ -85,6 +97,10 @@ static bool vfio_ap_register_irq_notifier(VFIOAPDevice 
*vapdev,
          notifier = &vapdev->req_notifier;
          fd_read = vfio_ap_req_notifier_handler;
          break;
+    case VFIO_AP_CFG_CHG_IRQ_INDEX:
+        notifier = &vapdev->cfg_notifier;
+        fd_read = vfio_ap_cfg_chg_notifier_handler;
+        break;
      default:
          error_setg(errp, "vfio: Unsupported device irq(%d)", irq);
          return false;
@@ -136,6 +152,9 @@ static void vfio_ap_unregister_irq_notifier(VFIOAPDevice 
*vapdev,
      case VFIO_AP_REQ_IRQ_INDEX:
          notifier = &vapdev->req_notifier;
          break;
+    case VFIO_AP_CFG_CHG_IRQ_INDEX:
+        notifier = &vapdev->cfg_notifier;
+        break;
      default:
          error_report("vfio: Unsupported device irq(%d)", irq);
          return;
@@ -175,6 +194,15 @@ static void vfio_ap_realize(DeviceState *dev, Error **errp)
          warn_report_err(err);
      }

+ if (!vfio_ap_register_irq_notifier(vapdev, VFIO_AP_CFG_CHG_IRQ_INDEX, &err))

+    {
+        /*
+         * Report this error, but do not make it a failing condition.
+         * Lack of this IRQ in the host does not prevent normal operation.
+         */
+        warn_report_err(err);
+    }
+
      return;

error:

@@ -187,6 +215,7 @@ static void vfio_ap_unrealize(DeviceState *dev)
      VFIOAPDevice *vapdev = VFIO_AP_DEVICE(dev);

vfio_ap_unregister_irq_notifier(vapdev, VFIO_AP_REQ_IRQ_INDEX);

+    vfio_ap_unregister_irq_notifier(vapdev, VFIO_AP_CFG_CHG_IRQ_INDEX);
      vfio_detach_device(&vapdev->vdev);
      g_free(vapdev->vdev.name);
  }