[PATCH v3 05/10] hyper-v: use fast hypercall for HVCALL_SIGNAL_EVENT

[Vitaly Kuznetsov]

We need to pass only 8 bytes of input for HvSignalEvent which makes it a
perfect fit for fast hypercall. hv_input_signal_event_buffer is not needed
any more and hv_input_signal_event is converted to union for convenience.

Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
Acked-by: K. Y. Srinivasan <k...@microsoft.com>
Tested-by: Simon Xiao <six...@microsoft.com>
Tested-by: Srikanth Myakam <v-...@microsoft.com>
---
 drivers/hv/channel_mgmt.c | 15 +++++----------
 drivers/hv/connection.c   |  3 ++-
 include/linux/hyperv.h    | 19 ++++++++-----------
 3 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 0fabd41..ee2a8dd 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -806,20 +806,15 @@ static void vmbus_onoffer(struct 
vmbus_channel_message_header *hdr)
        /*
         * Setup state for signalling the host.
         */
-       newchannel->sig_event = (struct hv_input_signal_event *)
-                               (ALIGN((unsigned long)
-                               &newchannel->sig_buf,
-                               HV_HYPERCALL_PARAM_ALIGN));
-
-       newchannel->sig_event->connectionid.asu32 = 0;
-       newchannel->sig_event->connectionid.u.id = VMBUS_EVENT_CONNECTION_ID;
-       newchannel->sig_event->flag_number = 0;
-       newchannel->sig_event->rsvdz = 0;
+       newchannel->sig_event.connectionid.asu32 = 0;
+       newchannel->sig_event.connectionid.u.id = VMBUS_EVENT_CONNECTION_ID;
+       newchannel->sig_event.flag_number = 0;
+       newchannel->sig_event.rsvdz = 0;
 
        if (vmbus_proto_version != VERSION_WS2008) {
                newchannel->is_dedicated_interrupt =
                                (offer->is_dedicated_interrupt != 0);
-               newchannel->sig_event->connectionid.u.id =
+               newchannel->sig_event.connectionid.u.id =
                                offer->connection_id;
        }
 
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 4a0a9f6..51f8cb2 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -408,6 +408,7 @@ void vmbus_set_event(struct vmbus_channel *channel)
        if (!channel->is_dedicated_interrupt)
                vmbus_send_interrupt(child_relid);
 
-       hv_do_hypercall(HVCALL_SIGNAL_EVENT, channel->sig_event, NULL);
+       hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT,
+                             channel->sig_event.as_uint64);
 }
 EXPORT_SYMBOL_GPL(vmbus_set_event);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index d1ae02d..68a5772 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -678,15 +678,13 @@ union hv_connection_id {
 };
 
 /* Definition of the hv_signal_event hypercall input structure. */
-struct hv_input_signal_event {
-       union hv_connection_id connectionid;
-       u16 flag_number;
-       u16 rsvdz;
-};
-
-struct hv_input_signal_event_buffer {
-       u64 align8;
-       struct hv_input_signal_event event;
+union hv_input_signal_event {
+       u64 as_uint64;
+       struct {
+               union hv_connection_id connectionid;
+               u16 flag_number;
+               u16 rsvdz;
+       };
 };
 
 enum hv_numa_policy {
@@ -771,8 +769,7 @@ struct vmbus_channel {
        } callback_mode;
 
        bool is_dedicated_interrupt;
-       struct hv_input_signal_event_buffer sig_buf;
-       struct hv_input_signal_event *sig_event;
+       union hv_input_signal_event sig_event;
 
        /*
         * Starting with win8, this field will be used to specify
-- 
2.9.3

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