[PATCH v5 6/7] spapr: use DEVICE_UNPLUG_ERROR to report unplug errors

[Daniel Henrique Barboza]

Linux Kernel 5.12 is now unisolating CPU DRCs in the device_removal
error path, signalling that the hotunplug process wasn't successful.
This allow us to send a DEVICE_UNPLUG_ERROR in drc_unisolate_logical()
to signal this error to the management layer.

We also have another error path in spapr_memory_unplug_rollback() for
configured LMB DRCs. Kernels older than 5.13 will not unisolate the LMBs
in the hotunplug error path, but it will reconfigure them. Let's send
the DEVICE_UNPLUG_ERROR event in that code path as well to cover the
case of older kernels.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr.c     |  9 ++++++++-
 hw/ppc/spapr_drc.c | 17 +++++++++++------
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 1611d7ab05..5459f9a7e9 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -29,6 +29,7 @@
 #include "qemu/datadir.h"
 #include "qapi/error.h"
 #include "qapi/qapi-events-machine.h"
+#include "qapi/qapi-events-qdev.h"
 #include "qapi/visitor.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/hostmem.h"
@@ -3686,13 +3687,19 @@ void spapr_memory_unplug_rollback(SpaprMachineState 
*spapr, DeviceState *dev)
 
     /*
      * Tell QAPI that something happened and the memory
-     * hotunplug wasn't successful.
+     * hotunplug wasn't successful. Keep sending
+     * MEM_UNPLUG_ERROR even while sending DEVICE_UNPLUG_ERROR
+     * until the deprecation MEM_UNPLUG_ERROR is due.
      */
     if (dev->id) {
         qapi_error = g_strdup_printf("Memory hotunplug rejected by the guest "
                                      "for device %s", dev->id);
         qapi_event_send_mem_unplug_error(dev->id, qapi_error);
     }
+
+    qapi_event_send_device_unplug_error(!!dev->id, dev->id,
+                                        dev->canonical_path,
+                                        qapi_error != NULL, qapi_error);
 }
 
 /* Callback to be called during DRC release. */
diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index a4d9496f76..a3a15fd2ed 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -17,6 +17,8 @@
 #include "hw/ppc/spapr_drc.h"
 #include "qom/object.h"
 #include "migration/vmstate.h"
+#include "qapi/error.h"
+#include "qapi/qapi-events-qdev.h"
 #include "qapi/visitor.h"
 #include "qemu/error-report.h"
 #include "hw/ppc/spapr.h" /* for RTAS return codes */
@@ -160,6 +162,10 @@ static uint32_t drc_unisolate_logical(SpaprDrc *drc)
          * means that the kernel is refusing the removal.
          */
         if (drc->unplug_requested && drc->dev) {
+            const char qapi_error_fmt[] = "Device hotunplug rejected by the "
+                                          "guest for device %s";
+            g_autofree char *qapi_error = NULL;
+
             if (spapr_drc_type(drc) == SPAPR_DR_CONNECTOR_TYPE_LMB) {
                 spapr = SPAPR_MACHINE(qdev_get_machine());
 
@@ -169,14 +175,13 @@ static uint32_t drc_unisolate_logical(SpaprDrc *drc)
             drc->unplug_requested = false;
 
             if (drc->dev->id) {
-                error_report("Device hotunplug rejected by the guest "
-                             "for device %s", drc->dev->id);
+                qapi_error = g_strdup_printf(qapi_error_fmt, drc->dev->id);
+                error_report(qapi_error_fmt, drc->dev->id);
             }
 
-            /*
-             * TODO: send a QAPI DEVICE_UNPLUG_ERROR event when
-             * it is implemented.
-             */
+            qapi_event_send_device_unplug_error(!!drc->dev->id, drc->dev->id,
+                                                drc->dev->canonical_path,
+                                                qapi_error != NULL, 
qapi_error);
         }
 
         return RTAS_OUT_SUCCESS; /* Nothing to do */
-- 
2.31.1