[Xen-devel] [PATCH v4 07/10] xen/arm: Release maintenance interrupt when CPU is hot-unplugged

[Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>]

When a CPU is hot-unplugged the maintenance interrupt has to be
released in order to free the memory that was allocated when the CPU
was hotplugged and interrupt requested. The interrupt was requested
using request_irq() which is called from start_secondary->
init_maintenance_interrupt. With this patch the interrupt will be
released when the CPU_DYING event is received by the callback which
is added in gic.c.

Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

---
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>
---
Changes in v3:
-Add notifier in order to trigger releasing of the  maintenance
 interrupt when the CPU is dying.

Changes in v4:
-Add includes alphabetically
-Added newline before the return in cpu_gic_notifier_init()
-Fix indentation in cpu_gic_callback() definition
-Added acked-by Julien
---
 xen/arch/arm/gic.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 653a815127..5474030386 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -27,6 +27,8 @@
 #include <xen/list.h>
 #include <xen/device_tree.h>
 #include <xen/acpi.h>
+#include <xen/cpu.h>
+#include <xen/notifier.h>
 #include <asm/p2m.h>
 #include <asm/domain.h>
 #include <asm/platform.h>
@@ -462,6 +464,35 @@ int gic_iomem_deny_access(const struct domain *d)
     return gic_hw_ops->iomem_deny_access(d);
 }
 
+static int cpu_gic_callback(struct notifier_block *nfb,
+                            unsigned long action,
+                            void *hcpu)
+{
+    switch ( action )
+    {
+    case CPU_DYING:
+        /* This is reverting the work done in init_maintenance_interrupt */
+        release_irq(gic_hw_ops->info->maintenance_irq, NULL);
+        break;
+    default:
+        break;
+    }
+
+    return NOTIFY_DONE;
+}
+
+static struct notifier_block cpu_gic_nfb = {
+    .notifier_call = cpu_gic_callback,
+};
+
+static int __init cpu_gic_notifier_init(void)
+{
+    register_cpu_notifier(&cpu_gic_nfb);
+
+    return 0;
+}
+__initcall(cpu_gic_notifier_init);
+
 /*
  * Local variables:
  * mode: C
-- 
2.13.0


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