Implement CPU hotplug on Arm

index e74d30d258..59349467de 100644
@@ -303,9 +303,15 @@ static void check_timer_irq_cfg(unsigned int irq, const char *which)
            "WARNING: %s-timer IRQ%u is not level triggered.\n", which, irq);
 }
 
+DEFINE_PER_CPU_READ_MOSTLY(struct irqaction, irq_hyp);
+DEFINE_PER_CPU_READ_MOSTLY(struct irqaction, irq_virt);
+
 /* Set up the timer interrupt on this CPU */
 void init_timer_interrupt(void)
 {
+    struct irqaction *hyp_action = &this_cpu(irq_hyp);
+    struct irqaction *virt_action = &this_cpu(irq_virt);
+
     /* Sensible defaults */
     WRITE_SYSREG64(0, CNTVOFF_EL2);     /* No VM-specific offset */
     /* Do not let the VMs program the physical timer, only read the physical counter */

@@ -314,10 +320,17 @@ void init_timer_interrupt(void)
     WRITE_SYSREG(0, CNTHP_CTL_EL2);   /* Hypervisor's timer disabled */
     isb();
 
-    request_irq(timer_irq[TIMER_HYP_PPI], 0, htimer_interrupt,
-                "hyptimer", NULL);
-    request_irq(timer_irq[TIMER_VIRT_PPI], 0, vtimer_interrupt,
-                   "virtimer", NULL);
+    hyp_action->name = "hyptimer";
+    hyp_action->handler = htimer_interrupt;
+    hyp_action->dev_id = NULL;
+    hyp_action->free_on_release = 0;
+    setup_irq(timer_irq[TIMER_HYP_PPI], 0, hyp_action);
+
+    virt_action->name = "virtimer";
+    virt_action->handler = vtimer_interrupt;
+    virt_action->dev_id = NULL;
+    virt_action->free_on_release = 0;
+    setup_irq(timer_irq[TIMER_VIRT_PPI], 0, virt_action);
 
     check_timer_irq_cfg(timer_irq[TIMER_HYP_PPI], "hypervisor");
     check_timer_irq_cfg(timer_irq[TIMER_VIRT_PPI], "virtual");

index 260ee64cca..ed6853bb32 100644
@@ -386,10 +386,17 @@ void gic_dump_info(struct vcpu *v)
     gic_hw_ops->dump_state(v);
 }
 
+DEFINE_PER_CPU_READ_MOSTLY(struct irqaction, irq_maintenance);
+
 void init_maintenance_interrupt(void)
 {
-    request_irq(gic_hw_ops->info->maintenance_irq, 0, maintenance_interrupt,
-                "irq-maintenance", NULL);
+    struct irqaction *maintenance = &this_cpu(irq_maintenance);
+
+    maintenance->name = "irq-maintenance";
+    maintenance->handler = maintenance_interrupt;
+    maintenance->dev_id = NULL;
+    maintenance->free_on_release = 0;
+    setup_irq(gic_hw_ops->info->maintenance_irq, 0, maintenance);
 }
 
 int gic_make_hwdom_dt_node(const struct domain *d,

index 32cab4feff..fecd649db1 100644
@@ -12,6 +12,8 @@
 #include <xen/dt-overlay.h>
 #include <xen/errno.h>
 #include <xen/hypercall.h>
+#include <xen/cpu.h>
+#include <xsm/xsm.h>
 #include <asm/arm64/sve.h>
 #include <public/sysctl.h>
 

@@ -23,6 +25,42 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
                                        XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK);
 }
 
+#ifdef CONFIG_ARM_64
+static long cpu_up_helper(void *data)
+{
+    unsigned long cpu = (unsigned long) data;
+    return cpu_up(cpu);
+}
+
+static long cpu_down_helper(void *data)
+{
+    unsigned long cpu = (unsigned long) data;
+    return cpu_down(cpu);
+}
+
+static long cpu_hotplug_sysctl(struct xen_sysctl_cpu_hotplug *hotplug)
+{
+    int ret;
+
+    switch (hotplug->op) {
+        case XEN_SYSCTL_CPU_HOTPLUG_ONLINE:
+            ret = xsm_resource_plug_core(XSM_HOOK);
+            if ( ret )
+                return ret;
+            return continue_hypercall_on_cpu(0, cpu_up_helper, _p(hotplug->cpu));
+
+        case XEN_SYSCTL_CPU_HOTPLUG_OFFLINE:
+            ret = xsm_resource_unplug_core(XSM_HOOK);
+            if ( ret )
+                return ret;
+            return continue_hypercall_on_cpu(0, cpu_down_helper, _p(hotplug->cpu));
+
+        default:
+            return -EOPNOTSUPP;
+    }
+}
+#endif
+
 long arch_do_sysctl(struct xen_sysctl *sysctl,
                     XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
 {

@@ -34,6 +72,13 @@ long arch_do_sysctl(struct xen_sysctl *sysctl,
         ret = dt_overlay_sysctl(&sysctl->u.dt_overlay);
         break;
 
+/* CPU Hotplug only implemented for 64-bit Arm */
+#ifdef CONFIG_ARM_64
+    case XEN_SYSCTL_cpu_hotplug:
+        ret = cpu_hotplug_sysctl(&sysctl->u.cpu_hotplug);
+        break;
+#endif
+
     default:
         ret = -ENOSYS;
         break;