Commit 3a28fa35 authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman

Drivers: hv: vmbus: Implement per-CPU mapping of relid to channel

Currently the mapping of the relID to channel is done under the protection of a
single spin lock. Starting with ws2012, each channel is bound to a specific VCPU
in the guest. Use this binding to eliminate the spin lock by setting up
per-cpu state for mapping relId to the channel.
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: default avatarHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d3ba720d
......@@ -149,6 +149,7 @@ static struct vmbus_channel *alloc_channel(void)
spin_lock_init(&channel->sc_lock);
INIT_LIST_HEAD(&channel->sc_list);
INIT_LIST_HEAD(&channel->percpu_list);
channel->controlwq = create_workqueue("hv_vmbus_ctl");
if (!channel->controlwq) {
......@@ -188,7 +189,20 @@ static void free_channel(struct vmbus_channel *channel)
queue_work(vmbus_connection.work_queue, &channel->work);
}
static void percpu_channel_enq(void *arg)
{
struct vmbus_channel *channel = arg;
int cpu = smp_processor_id();
list_add_tail(&channel->percpu_list, &hv_context.percpu_list[cpu]);
}
static void percpu_channel_deq(void *arg)
{
struct vmbus_channel *channel = arg;
list_del(&channel->percpu_list);
}
/*
* vmbus_process_rescind_offer -
......@@ -210,6 +224,12 @@ 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));
if (channel->target_cpu != smp_processor_id())
smp_call_function_single(channel->target_cpu,
percpu_channel_deq, channel, true);
else
percpu_channel_deq(channel);
if (channel->primary_channel == NULL) {
spin_lock_irqsave(&vmbus_connection.channel_lock, flags);
list_del(&channel->listentry);
......@@ -245,6 +265,7 @@ static void vmbus_process_offer(struct work_struct *work)
work);
struct vmbus_channel *channel;
bool fnew = true;
bool enq = false;
int ret;
unsigned long flags;
......@@ -264,12 +285,22 @@ static void vmbus_process_offer(struct work_struct *work)
}
}
if (fnew)
if (fnew) {
list_add_tail(&newchannel->listentry,
&vmbus_connection.chn_list);
enq = true;
}
spin_unlock_irqrestore(&vmbus_connection.channel_lock, flags);
if (enq) {
if (newchannel->target_cpu != smp_processor_id())
smp_call_function_single(newchannel->target_cpu,
percpu_channel_enq,
newchannel, true);
else
percpu_channel_enq(newchannel);
}
if (!fnew) {
/*
* Check to see if this is a sub-channel.
......@@ -282,6 +313,14 @@ static void vmbus_process_offer(struct work_struct *work)
spin_lock_irqsave(&channel->sc_lock, flags);
list_add_tail(&newchannel->sc_list, &channel->sc_list);
spin_unlock_irqrestore(&channel->sc_lock, flags);
if (newchannel->target_cpu != smp_processor_id())
smp_call_function_single(newchannel->target_cpu,
percpu_channel_enq,
newchannel, true);
else
percpu_channel_enq(newchannel);
newchannel->state = CHANNEL_OPEN_STATE;
if (channel->sc_creation_callback != NULL)
channel->sc_creation_callback(newchannel);
......
......@@ -234,6 +234,28 @@ int vmbus_connect(void)
return ret;
}
/*
* Map the given relid to the corresponding channel based on the
* per-cpu list of channels that have been affinitized to this CPU.
* This will be used in the channel callback path as we can do this
* mapping in a lock-free fashion.
*/
static struct vmbus_channel *pcpu_relid2channel(u32 relid)
{
struct vmbus_channel *channel;
struct vmbus_channel *found_channel = NULL;
int cpu = smp_processor_id();
struct list_head *pcpu_head = &hv_context.percpu_list[cpu];
list_for_each_entry(channel, pcpu_head, percpu_list) {
if (channel->offermsg.child_relid == relid) {
found_channel = channel;
break;
}
}
return found_channel;
}
/*
* relid2channel - Get the channel object given its
......@@ -285,7 +307,7 @@ static void process_chn_event(u32 relid)
* Find the channel based on this relid and invokes the
* channel callback to process the event
*/
channel = relid2channel(relid);
channel = pcpu_relid2channel(relid);
if (!channel) {
pr_err("channel not found for relid - %u\n", relid);
......
......@@ -383,6 +383,8 @@ void hv_synic_init(void *arg)
*/
rdmsrl(HV_X64_MSR_VP_INDEX, vp_index);
hv_context.vp_index[cpu] = (u32)vp_index;
INIT_LIST_HEAD(&hv_context.percpu_list[cpu]);
return;
}
......
......@@ -510,6 +510,11 @@ struct hv_context {
* basis.
*/
struct tasklet_struct *event_dpc[NR_CPUS];
/*
* To optimize the mapping of relid to channel, maintain
* per-cpu list of the channels based on their CPU affinity.
*/
struct list_head percpu_list[NR_CPUS];
};
extern struct hv_context hv_context;
......
......@@ -734,6 +734,11 @@ struct vmbus_channel {
* Support per-channel state for use by vmbus drivers.
*/
void *per_channel_state;
/*
* To support per-cpu lookup mapping of relid to channel,
* link up channels based on their CPU affinity.
*/
struct list_head percpu_list;
};
static inline void set_channel_read_state(struct vmbus_channel *c, bool state)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment