[PATCH v3 4/6] drivers:hv: Export a function that maps Linux proc num onto Hyper-V proc num

[jakeo@microsoft.com]

From: Jake Oshins <jakeo@microsoft.com>

This patch exports a function which maps Linux CPU number onto Hyper-V
virtual processor number.  This is necessary in order to map message-
signaled interrupts (MSIs) into a VM, as the hypervisor needs to know the
right target VP.

Signed-off-by: Jake Oshins <jakeo@microsoft.com>
---
 drivers/hv/vmbus_drv.c | 17 +++++++++++++++++
 include/linux/hyperv.h |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 9b4fc1a..3a95786 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1154,6 +1154,23 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
 }
 EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);
 
+/**
+ * vmbus_cpu_number_to_vp_number() - Map CPU to VP.
+ * @cpu_number: CPU number in Linux terms
+ *
+ * This function returns the mapping between the Linux processor
+ * number and the hypervisor's virtual processor number, useful
+ * in making hypercalls and such that talk about specific
+ * processors.
+ *
+ * Return: Virtual processor number in Hyper-V terms
+ */
+int vmbus_cpu_number_to_vp_number(int cpu_number)
+{
+	return hv_context.vp_index[cpu_number];
+}
+EXPORT_SYMBOL_GPL(vmbus_cpu_number_to_vp_number);
+
 static int vmbus_acpi_add(struct acpi_device *device)
 {
 	acpi_status result;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index ffd98d7..2e40f4d 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -987,6 +987,8 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
 			resource_size_t size, resource_size_t align,
 			bool fb_overlap_ok);
 
+int vmbus_cpu_number_to_vp_number(int cpu_number);
+
 /**
  * VMBUS_DEVICE - macro used to describe a specific hyperv vmbus device
  *
-- 
1.9.1