Drivers: hv: Add state to manage incoming channel interrupt load

Add state to bind a channel to a specific VCPU. This will help us better
distribute incoming interrupt load.

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>

3 files changed, 22 insertions, 3 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 70a34daa04c1..9303252b2e19 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -181,7 +181,7 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
         open_msg->ringbuffer_gpadlhandle = newchannel->ringbuffer_gpadlhandle;
         open_msg->downstream_ringbuffer_pageoffset = send_ringbuffer_size >>
                                                   PAGE_SHIFT;
-        open_msg->server_contextarea_gpadlhandle = 0;
+        open_msg->target_vp = newchannel->target_vp;
 
         if (userdatalen > MAX_USER_DEFINED_BYTES) {
                 err = -EINVAL;
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index f4d990285d99..56ed45c74d01 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -302,6 +302,8 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
                                 offer->connection_id;
         }
 
+        newchannel->target_vp = 0;
+
         memcpy(&newchannel->offermsg, offer,
                sizeof(struct vmbus_channel_offer_channel));
         newchannel->monitor_grp = (u8)offer->monitorid / 32;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index c6e2c44a1be9..8c3cb1fc34d4 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -732,8 +732,15 @@ struct vmbus_channel_open_channel {
         /* GPADL for the channel's ring buffer. */
         u32 ringbuffer_gpadlhandle;
 
-        /* GPADL for the channel's server context save area. */
-        u32 server_contextarea_gpadlhandle;
+        /*
+         * Starting with win8, this field will be used to specify
+         * the target virtual processor on which to deliver the interrupt for
+         * the host to guest communication.
+         * Prior to win8, incoming channel interrupts would only
+         * be delivered on cpu 0. Setting this value to 0 would
+         * preserve the earlier behavior.
+         */
+        u32 target_vp;
 
         /*
         * The upstream ring buffer begins at offset zero in the memory
@@ -971,6 +978,16 @@ struct vmbus_channel {
         bool is_dedicated_interrupt;
         struct hv_input_signal_event_buffer sig_buf;
         struct hv_input_signal_event *sig_event;
+
+        /*
+         * Starting with win8, this field will be used to specify
+         * the target virtual processor on which to deliver the interrupt for
+         * the host to guest communication.
+         * Prior to win8, incoming channel interrupts would only
+         * be delivered on cpu 0. Setting this value to 0 would
+         * preserve the earlier behavior.
+         */
+        u32 target_vp;
 };
 
 static inline void set_channel_read_state(struct vmbus_channel *c, bool state)