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authorK. Y. Srinivasan <kys@microsoft.com>2013-05-23 12:02:32 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-06-03 14:09:14 -0700
commite68d2971d26577b932a16333ce165af98a96e068 (patch)
tree641b8143d41993366c4d0d0b6546a1695acba83b /drivers/hv/channel_mgmt.c
parent8d7bda51888d14c07cbebacc5a10be776477bb63 (diff)
downloadlinux-e68d2971d26577b932a16333ce165af98a96e068.tar.bz2
Drivers: hv: vmbus: Implement multi-channel support
Starting with Win8, the host supports multiple sub-channels for a given device. As in the past, the initial channel offer specifies the device and is associated with both the type and the instance GUIDs. For performance critical devices, the host may support multiple sub-channels. The sub-channels share the same type and instance GUID as the primary channel. The number of sub-channels offerrred to the guest depends on the number of virtual CPUs assigned to the guest. The guest can request the creation of these sub-channels and once created and opened, the guest can distribute the traffic across all the channels (the primary and the sub-channels). A request sent on a sub-channel will have the response delivered on the same sub-channel. At channel (sub-channel) creation we bind the channel interrupt to a CPU and with this sub-channel support we will be able to spread the interrupt load of a given device across all available CPUs. 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>
Diffstat (limited to 'drivers/hv/channel_mgmt.c')
-rw-r--r--drivers/hv/channel_mgmt.c119
1 files changed, 115 insertions, 4 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 21ef68934a20..0df75908200e 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -115,6 +115,9 @@ static struct vmbus_channel *alloc_channel(void)
return NULL;
spin_lock_init(&channel->inbound_lock);
+ spin_lock_init(&channel->sc_lock);
+
+ INIT_LIST_HEAD(&channel->sc_list);
channel->controlwq = create_workqueue("hv_vmbus_ctl");
if (!channel->controlwq) {
@@ -166,6 +169,7 @@ static void vmbus_process_rescind_offer(struct work_struct *work)
struct vmbus_channel,
work);
unsigned long flags;
+ struct vmbus_channel *primary_channel;
struct vmbus_channel_relid_released msg;
vmbus_device_unregister(channel->device_obj);
@@ -174,9 +178,16 @@ static void vmbus_process_rescind_offer(struct work_struct *work)
msg.header.msgtype = CHANNELMSG_RELID_RELEASED;
vmbus_post_msg(&msg, sizeof(struct vmbus_channel_relid_released));
- spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
- list_del(&channel->listentry);
- spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
+ if (channel->primary_channel == NULL) {
+ spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
+ list_del(&channel->listentry);
+ spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
+ } else {
+ primary_channel = channel->primary_channel;
+ spin_lock_irqsave(&primary_channel->sc_lock, flags);
+ list_del(&channel->listentry);
+ spin_unlock_irqrestore(&primary_channel->sc_lock, flags);
+ }
free_channel(channel);
}
@@ -228,6 +239,24 @@ static void vmbus_process_offer(struct work_struct *work)
spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
if (!fnew) {
+ /*
+ * Check to see if this is a sub-channel.
+ */
+ if (newchannel->offermsg.offer.sub_channel_index != 0) {
+ /*
+ * Process the sub-channel.
+ */
+ newchannel->primary_channel = channel;
+ spin_lock_irqsave(&channel->sc_lock, flags);
+ list_add_tail(&newchannel->sc_list, &channel->sc_list);
+ spin_unlock_irqrestore(&channel->sc_lock, flags);
+ newchannel->state = CHANNEL_OPEN_STATE;
+ if (channel->sc_creation_callback != NULL)
+ channel->sc_creation_callback(newchannel);
+
+ return;
+ }
+
free_channel(newchannel);
return;
}
@@ -685,4 +714,86 @@ cleanup:
return ret;
}
-/* eof */
+/*
+ * Retrieve the (sub) channel on which to send an outgoing request.
+ * When a primary channel has multiple sub-channels, we choose a
+ * channel whose VCPU binding is closest to the VCPU on which
+ * this call is being made.
+ */
+struct vmbus_channel *vmbus_get_outgoing_channel(struct vmbus_channel *primary)
+{
+ struct list_head *cur, *tmp;
+ int cur_cpu = hv_context.vp_index[smp_processor_id()];
+ struct vmbus_channel *cur_channel;
+ struct vmbus_channel *outgoing_channel = primary;
+ int cpu_distance, new_cpu_distance;
+
+ if (list_empty(&primary->sc_list))
+ return outgoing_channel;
+
+ list_for_each_safe(cur, tmp, &primary->sc_list) {
+ cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
+ if (cur_channel->state != CHANNEL_OPENED_STATE)
+ continue;
+
+ if (cur_channel->target_vp == cur_cpu)
+ return cur_channel;
+
+ cpu_distance = ((outgoing_channel->target_vp > cur_cpu) ?
+ (outgoing_channel->target_vp - cur_cpu) :
+ (cur_cpu - outgoing_channel->target_vp));
+
+ new_cpu_distance = ((cur_channel->target_vp > cur_cpu) ?
+ (cur_channel->target_vp - cur_cpu) :
+ (cur_cpu - cur_channel->target_vp));
+
+ if (cpu_distance < new_cpu_distance)
+ continue;
+
+ outgoing_channel = cur_channel;
+ }
+
+ return outgoing_channel;
+}
+EXPORT_SYMBOL_GPL(vmbus_get_outgoing_channel);
+
+static void invoke_sc_cb(struct vmbus_channel *primary_channel)
+{
+ struct list_head *cur, *tmp;
+ struct vmbus_channel *cur_channel;
+
+ if (primary_channel->sc_creation_callback == NULL)
+ return;
+
+ list_for_each_safe(cur, tmp, &primary_channel->sc_list) {
+ cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
+
+ primary_channel->sc_creation_callback(cur_channel);
+ }
+}
+
+void vmbus_set_sc_create_callback(struct vmbus_channel *primary_channel,
+ void (*sc_cr_cb)(struct vmbus_channel *new_sc))
+{
+ primary_channel->sc_creation_callback = sc_cr_cb;
+}
+EXPORT_SYMBOL_GPL(vmbus_set_sc_create_callback);
+
+bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
+{
+ bool ret;
+
+ ret = !list_empty(&primary->sc_list);
+
+ if (ret) {
+ /*
+ * Invoke the callback on sub-channel creation.
+ * This will present a uniform interface to the
+ * clients.
+ */
+ invoke_sc_cb(primary);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);