[Qemu-devel] [PATCH v2 13/13] spapr/xive: fix device hotplug when VM is stopped

[Cédric Le Goater]

Instead of switching off the sources, set their state to PENDING to
possibly catch a hotplug event occuring while the VM is stopped. At
resume, check the previous state and if an interrupt was queued,
generate a trigger.

Signed-off-by: Cédric Le Goater <c...@kaod.org>
---
 hw/intc/spapr_xive_kvm.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
index 99a829fb3f60..64d160babb26 100644
--- a/hw/intc/spapr_xive_kvm.c
+++ b/hw/intc/spapr_xive_kvm.c
@@ -500,8 +500,16 @@ static void kvmppc_xive_change_state_handler(void *opaque, 
int running,
     if (running) {
         for (i = 0; i < xsrc->nr_irqs; i++) {
             uint8_t pq = xive_source_esb_get(xsrc, i);
-            if (xive_esb_read(xsrc, i, XIVE_ESB_SET_PQ_00 + (pq << 8)) != 0x1) 
{
-                error_report("XIVE: IRQ %d has an invalid state", i);
+            uint8_t old_pq;
+
+            old_pq = xive_esb_read(xsrc, i, XIVE_ESB_SET_PQ_00 + (pq << 8));
+
+            /*
+             * If an interrupt was queued (hotplug event) while VM was
+             * stopped, generate a trigger.
+             */
+            if (pq == XIVE_ESB_RESET && old_pq == XIVE_ESB_QUEUED) {
+                xive_esb_trigger(xsrc, i);
             }
         }
 
@@ -515,7 +523,15 @@ static void kvmppc_xive_change_state_handler(void *opaque, 
int running,
      * migration is in progress.
      */
     for (i = 0; i < xsrc->nr_irqs; i++) {
-        uint8_t pq = xive_esb_read(xsrc, i, XIVE_ESB_SET_PQ_01);
+        uint8_t pq = xive_esb_read(xsrc, i, XIVE_ESB_GET);
+
+        /*
+         * PQ is set to PENDING to possibly catch a hotplug event
+         * occuring while the VM is stopped.
+         */
+        if (pq != XIVE_ESB_OFF) {
+            pq = xive_esb_read(xsrc, i, XIVE_ESB_SET_PQ_10);
+        }
         xive_source_esb_set(xsrc, i, pq);
     }
 
-- 
2.20.1