qemu/arm-virt-Correct-timing-of-pause-all-vcpus-for-hot-p.patch

From 41f30679648676d4d62b1ae9026dde77fa9895d5 Mon Sep 17 00:00:00 2001
From: Kunkun Jiang <jiangkunkun@huawei.com>
Date: Tue, 14 Feb 2023 20:39:07 +0800
Subject: [PATCH] arm/virt: Correct timing of pause all vcpus for hot-plugged
 CPUs

When dealing with hot-plugging cpus, it may fail when realize cpu.
Such a failure would make paused vcpus unrecoverable. So we only
pause all vcpus when needed. Add removed some unnecessary checks.

Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
---
 hw/arm/virt.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 7d5b332594..4c876fcf16 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2747,13 +2747,6 @@ static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev,
                                      &error_abort);
         }
     }
-
-    /* If we use KVM accel, we should pause all vcpus to
-     * allow hot access of vcpu registers.
-     */
-    if (dev->hotplugged && kvm_enabled()) {
-        pause_all_vcpus();
-    }
 }
 
 static void virt_cpu_plug(HotplugHandler *hotplug_dev,
@@ -2773,6 +2766,10 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
 
     /* For CPU that is cold/hot plugged */
     if (ncpu >= ms->smp.cpus) {
+        if (dev->hotplugged) {
+            pause_all_vcpus();
+        }
+
         /* Realize GIC related parts of CPU */
         assert(vms->gic_version == 3);
         gicv3 = ARM_GICV3_COMMON(vms->gic);
@@ -2803,6 +2800,10 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
         cpu_hotplug_register_reset(ncpu);
         cpu_hotplug_reset_manually(ncpu);
         cpu_synchronize_post_reset(cs);
+
+        if (dev->hotplugged) {
+            resume_all_vcpus();
+        }
     }
 
     if (dev->hotplugged && kvm_enabled()) {
-- 
2.27.0