Hi, Jeremy, followed patch port pcpu hotplug support to 2.6.32 pvops dom0. I don't know if xen/next-2.6.32 branch is the right base. If it is not, can you please advice me which branch should I base on?

Thanks
--jyh

Add cpu hotplug support for 2.6.32 branch

Add physical CPU hotplug support to origin/xen/next-2.6.32 branch.
Please notice that, even with this change, the acpi_processor->id is 
still always -1. This is because several workaround in PM side depends
on acpi_processor->id == -1. As the CPU hotplug logic does not depends
on acpi_processor->id, I'd still keep it no changes.

But we need change the acpi_processor->id in the future.

Signed-off-by: Jiang, Yunhong <yunhong.jiang@intel.com>


diff --git a/drivers/acpi/processor_xen.c b/drivers/acpi/processor_xen.c
index 2f37c9c..305398d 100644
--- a/drivers/acpi/processor_xen.c
+++ b/drivers/acpi/processor_xen.c
@@ -39,6 +39,7 @@
 #include <acpi/acpi_drivers.h>
 #include <acpi/processor.h>
 #include <xen/acpi.h>
+#include <xen/pcpu.h>
 
 #define PREFIX "ACPI: "
 
@@ -82,6 +83,42 @@ struct acpi_driver xen_acpi_processor_driver = {
 		},
 };
 
+static int is_processor_present(acpi_handle handle)
+{
+	acpi_status status;
+	unsigned long long sta = 0;
+
+
+	status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
+
+	if (ACPI_SUCCESS(status) && (sta & ACPI_STA_DEVICE_PRESENT))
+		return 1;
+
+	/*
+	 * _STA is mandatory for a processor that supports hot plug
+	 */
+	if (status == AE_NOT_FOUND)
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+				"Processor does not support hot plug\n"));
+	else
+		ACPI_EXCEPTION((AE_INFO, status,
+				"Processor Device is not present"));
+	return 0;
+}
+
+static acpi_status
+xen_acpi_processor_hotadd_init(struct acpi_processor *pr, int *p_cpu)
+{
+	if (!is_processor_present(pr->handle))
+		return AE_ERROR;
+
+	if (processor_cntl_xen_notify(pr,
+				PROCESSOR_HOTPLUG, HOTPLUG_TYPE_ADD))
+		return AE_ERROR;
+
+	return AE_OK;
+}
+
 static int xen_acpi_processor_get_info(struct acpi_device *device)
 {
 	acpi_status status = 0;
@@ -164,14 +201,12 @@ static int xen_acpi_processor_get_info(struct acpi_device *device)
 	 *  They should be ignored _iff they are physically not present.
 	 *
 	 */
-#if 0
-	if (pr->id == -1) {
+	if (xen_pcpu_index(pr->acpi_id, 1) == -1) {
 		if (ACPI_FAILURE
-		    (acpi_processor_hotadd_init(pr->handle, &pr->id))) {
+		    (xen_acpi_processor_hotadd_init(pr, &pr->id))) {
 			return -ENODEV;
 		}
 	}
-#endif
 
 	/*
 	 * On some boxes several processors use the same processor bus id.
diff --git a/drivers/xen/pcpu.c b/drivers/xen/pcpu.c
index 6450c17..6d1a770 100644
--- a/drivers/xen/pcpu.c
+++ b/drivers/xen/pcpu.c
@@ -313,6 +313,38 @@ static struct pcpu *_sync_pcpu(int cpu_num, int *max_id, int *result)
 	return pcpu;
 }
 
+int xen_pcpu_index(uint32_t id, int is_acpiid)
+{
+	int cpu_num = 0, max_id = 0, ret;
+	xen_platform_op_t op = {
+		.cmd            = XENPF_get_cpuinfo,
+		.interface_version  = XENPF_INTERFACE_VERSION,
+	};
+	struct xenpf_pcpuinfo *info = &op.u.pcpu_info;
+
+	info->xen_cpuid = 0;
+	ret = HYPERVISOR_dom0_op(&op);
+	if (ret)
+		return -1;
+	max_id = op.u.pcpu_info.max_present;
+
+	while ((cpu_num <= max_id)) {
+		info->xen_cpuid = cpu_num;
+		ret = HYPERVISOR_dom0_op(&op);
+		if (ret)
+			continue;
+
+		if (op.u.pcpu_info.max_present > max_id)
+			max_id = op.u.pcpu_info.max_present;
+		if (id == (is_acpiid ? info->acpi_id : info->apic_id))
+			return cpu_num;
+		cpu_num++;
+	}
+
+    return -1;
+}
+EXPORT_SYMBOL(xen_pcpu_index);
+
 /*
  * Sync dom0's pcpu information with xen hypervisor's
  */
@@ -417,4 +449,4 @@ static int __init xen_pcpu_init(void)
 	return err;
 }
 
-subsys_initcall(xen_pcpu_init);
+arch_initcall(xen_pcpu_init);
diff --git a/include/xen/pcpu.h b/include/xen/pcpu.h
index fb2bf6b..7e8f9d1 100644
--- a/include/xen/pcpu.h
+++ b/include/xen/pcpu.h
@@ -27,4 +27,6 @@ static inline int xen_pcpu_online(uint32_t flags)
 extern int register_xen_pcpu_notifier(struct notifier_block *nb);
 
 extern void unregister_xen_pcpu_notifier(struct notifier_block *nb);
+
+extern int xen_pcpu_index(uint32_t acpi_id, int is_acpiid);
 #endif