Drivers: hv: Setup a mapping for Hyper-V's notion cpu ID

On win8 (ws2012), incoming vmbus interrupt load can be spread across all
available VCPUs in the guest. On a per-channel basis, the interrupts can
be bound to specific CPUs. The Linux notion of cpu ID may be different
from that of the hypervisor's. Setup a mapping structure.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 1bc7500fb84c..6bbc197cbdfa 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -502,6 +502,16 @@ struct hv_context {
 
         void *synic_message_page[NR_CPUS];
         void *synic_event_page[NR_CPUS];
+        /*
+         * Hypervisor's notion of virtual processor ID is different from
+         * Linux' notion of CPU ID. This information can only be retrieved
+         * in the context of the calling CPU. Setup a map for easy access
+         * to this information:
+         *
+         * vp_index[a] is the Hyper-V's processor ID corresponding to
+         * Linux cpuid 'a'.
+         */
+        u32 vp_index[NR_CPUS];
 };
 
 extern struct hv_context hv_context;