From: Magnus Kulke <magnuskulke@linux.microsoft.com>

In MSHV the hypervisor APIC is always used, so we to implement this hook
to make sure the AP's vcpu thread is not blocked waiting for an INIT SIPI
by the BSP. Without this change soft reboots with -smp cpus>=2 will
hang.

Signed-off-by: Magnus Kulke <magnuskulke@linux.microsoft.com>
Reviewed-by: Mohamed Mediouni <mohamed@unpredictable.fr>
---
 accel/mshv/mshv-all.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/accel/mshv/mshv-all.c b/accel/mshv/mshv-all.c
index 5ce76e86db..6c0ddbf3ca 100644
--- a/accel/mshv/mshv-all.c
+++ b/accel/mshv/mshv-all.c
@@ -704,11 +704,23 @@ static const TypeInfo mshv_accel_type = {
     .instance_size = sizeof(MshvState),
 };
 
+/*
+ * MSHV manages the LAPIC in the hypervisor. SIPI for APs are handled
+ * internally. Halted vCPUs must still enter mshv_cpu_exec() so that
+ * MSHV_RUN_VP is called and the hypervisor will deliver SIPI to wake APs.
+ */
+
+static bool mshv_vcpu_thread_is_idle(CPUState *cpu)
+{
+    return false;
+}
+
 static void mshv_accel_ops_class_init(ObjectClass *oc, const void *data)
 {
     AccelOpsClass *ops = ACCEL_OPS_CLASS(oc);
 
     ops->create_vcpu_thread = mshv_start_vcpu_thread;
+    ops->cpu_thread_is_idle = mshv_vcpu_thread_is_idle;
     ops->synchronize_post_init = mshv_cpu_synchronize_post_init;
     ops->synchronize_post_reset = mshv_cpu_synchronize_post_reset;
     ops->synchronize_state = mshv_cpu_synchronize;

-- 
2.45.4