Drivers: hv: vmbus: Enable explicit signaling policy for NIC channels

For synthetic NIC channels, enable explicit signaling policy as netvsc wants to
explicitly control when the host is to be signaled.

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

4 files changed, 20 insertions, 18 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index e47d37d21d56..9a49505a8e06 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -650,7 +650,7 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
         bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
         ret = hv_ringbuffer_write(&channel->outbound, bufferlist, num_vecs,
-                                  &signal, lock);
+                                  &signal, lock, channel->signal_policy);
 
         /*
          * Signalling the host is conditional on many factors:
@@ -671,11 +671,6 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
          * mechanism which can hurt the performance otherwise.
          */
 
-        if (channel->signal_policy)
-                signal = true;
-        else
-                kick_q = true;
-
         if (((ret == 0) && kick_q && signal) ||
             (ret && !is_hvsock_channel(channel)))
                 vmbus_setevent(channel);
@@ -768,7 +763,7 @@ int vmbus_sendpacket_pagebuffer_ctl(struct vmbus_channel *channel,
         bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
         ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3,
-                                  &signal, lock);
+                                  &signal, lock, channel->signal_policy);
 
         /*
          * Signalling the host is conditional on many factors:
@@ -786,11 +781,6 @@ int vmbus_sendpacket_pagebuffer_ctl(struct vmbus_channel *channel,
          * enough condition that it should not matter.
          */
 
-        if (channel->signal_policy)
-                signal = true;
-        else
-                kick_q = true;
-
         if (((ret == 0) && kick_q && signal) || (ret))
                 vmbus_setevent(channel);
 
@@ -852,7 +842,7 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
         bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
         ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3,
-                                  &signal, lock);
+                                  &signal, lock, channel->signal_policy);
 
         if (ret == 0 && signal)
                 vmbus_setevent(channel);
@@ -917,7 +907,7 @@ int vmbus_sendpacket_multipagebuffer(struct vmbus_channel *channel,
         bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
         ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3,
-                                  &signal, lock);
+                                  &signal, lock, channel->signal_policy);
 
         if (ret == 0 && signal)
                 vmbus_setevent(channel);
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 8818b92e5912..d8b64ba45b1d 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -426,6 +426,8 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
         }
 
         dev_type = hv_get_dev_type(&newchannel->offermsg.offer.if_type);
+        if (dev_type == HV_NIC)
+                set_channel_signal_state(newchannel, HV_SIGNAL_POLICY_EXPLICIT);
 
         init_vp_index(newchannel, dev_type);
 
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index dfa9fac100d8..ddcc3485520d 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -529,7 +529,8 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
 
 int hv_ringbuffer_write(struct hv_ring_buffer_info *ring_info,
                     struct kvec *kv_list,
-                    u32 kv_count, bool *signal, bool lock);
+                    u32 kv_count, bool *signal, bool lock,
+                    enum hv_signal_policy policy);
 
 int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
                        void *buffer, u32 buflen, u32 *buffer_actual_len,
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index fe586bf74e17..e3edcaee7ab3 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -66,12 +66,20 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi)
  *         arrived.
  */
 
-static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
+static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi,
+                              enum hv_signal_policy policy)
 {
         virt_mb();
         if (READ_ONCE(rbi->ring_buffer->interrupt_mask))
                 return false;
 
+        /*
+         * When the client wants to control signaling,
+         * we only honour the host interrupt mask.
+         */
+        if (policy == HV_SIGNAL_POLICY_EXPLICIT)
+                return true;
+
         /* check interrupt_mask before read_index */
         virt_rmb();
         /*
@@ -264,7 +272,8 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
 
 /* Write to the ring buffer. */
 int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
-                    struct kvec *kv_list, u32 kv_count, bool *signal, bool lock)
+                    struct kvec *kv_list, u32 kv_count, bool *signal, bool lock,
+                    enum hv_signal_policy policy)
 {
         int i = 0;
         u32 bytes_avail_towrite;
@@ -326,7 +335,7 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
         if (lock)
                 spin_unlock_irqrestore(&outring_info->ring_lock, flags);
 
-        *signal = hv_need_to_signal(old_write, outring_info);
+        *signal = hv_need_to_signal(old_write, outring_info, policy);
         return 0;
 }