xen/arm: propagate secondary GIC initialization failures

The GICv3 secondary_init() callback can fail while discovering or
waking a Redistributor, enabling LPIs, or setting up an ITS collection.
gic_init_secondary_cpu() currently discards that status. start_secondary()
then marks the CPU online even though its per-CPU GIC interface may be
unusable.

Return the callback status through the common GIC layer. Have
start_secondary() report the failure and stop the affected CPU before it
updates system features or is added to cpu_online_map.

Fixes: bc183a0235 ("xen/arm: Add support for GIC v3")
Signed-off-by: Mykola Kvach <mykola_kvach@epam.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

xen/arch/arm/gic.c

@@ -282,11 +282,17 @@ void smp_send_state_dump(unsigned int cpu)
 }
 
 /* Set up the per-CPU parts of the GIC for a secondary CPU */
-void gic_init_secondary_cpu(void)
+int gic_init_secondary_cpu(void)
 {
-    gic_hw_ops->secondary_init();
+    int rc = gic_hw_ops->secondary_init();
+
+    if ( rc )
+        return rc;
+
     /* Clear LR mask for secondary cpus */
     clear_cpu_lr_mask();
+
+    return 0;
 }
 
 /* Shut down the per-CPU GIC interface */

xen/arch/arm/include/asm/gic.h

@@ -291,7 +291,7 @@ extern void gic_preinit(void);
 /* Bring up the interrupt controller, and report # cpus attached */
 extern void gic_init(void);
 /* Bring up a secondary CPU's per-CPU GIC interface */
-extern void gic_init_secondary_cpu(void);
+extern int gic_init_secondary_cpu(void);
 /* Take down a CPU's per-CPU GIC interface */
 extern void gic_disable_cpu(void);
 /* setup the gic virtual interface for a guest */

xen/arch/arm/smpboot.c

@@ -319,6 +319,7 @@ smp_prepare_cpus(void)
 void asmlinkage noreturn start_secondary(void)
 {
     unsigned int cpuid = init_data.cpuid;
+    int rc;
 
     memset(get_cpu_info(), 0, sizeof (struct cpu_info));
 
@@ -366,6 +367,14 @@ void asmlinkage noreturn start_secondary(void)
         stop_cpu();
     }
 
+    rc = gic_init_secondary_cpu();
+    if ( rc )
+    {
+        printk(XENLOG_ERR "CPU%u: Failed to initialize the GIC: %d\n",
+               smp_processor_id(), rc);
+        stop_cpu();
+    }
+
     /*
      * system features must be updated only if we do not stop the core or
      * we might disable features due to a non used core (for example when
@@ -373,8 +382,6 @@ void asmlinkage noreturn start_secondary(void)
      */
     update_system_features(&current_cpu_data);
 
-    gic_init_secondary_cpu();
-
     set_current(idle_vcpu[cpuid]);
 
     /* Run local notifiers */