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Message-Id: <20210414150118.2843-3-parri.andrea@gmail.com>
Date: Wed, 14 Apr 2021 17:01:17 +0200
From: "Andrea Parri (Microsoft)" <parri.andrea@...il.com>
To: linux-kernel@...r.kernel.org
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
wei.liu@...nel.org, linux-hyperv@...r.kernel.org,
mikelley@...rosoft.com,
"Andrea Parri (Microsoft)" <parri.andrea@...il.com>
Subject: [PATCH v2 2/3] Drivers: hv: vmbus: Drivers: hv: vmbus: Introduce CHANNELMSG_MODIFYCHANNEL_RESPONSE
Introduce the CHANNELMSG_MODIFYCHANNEL_RESPONSE message type, and code
to receive and process such a message.
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@...il.com>
---
drivers/hv/channel.c | 99 ++++++++++++++++++++++++++++++++-------
drivers/hv/channel_mgmt.c | 42 +++++++++++++++++
drivers/hv/hv_trace.h | 15 ++++++
drivers/hv/vmbus_drv.c | 4 +-
include/linux/hyperv.h | 11 ++++-
5 files changed, 152 insertions(+), 19 deletions(-)
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index db30be8f9ccea..aa4ef75d8dee2 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -209,31 +209,96 @@ int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id,
}
EXPORT_SYMBOL_GPL(vmbus_send_tl_connect_request);
+static int send_modifychannel_without_ack(struct vmbus_channel *channel, u32 target_vp)
+{
+ struct vmbus_channel_modifychannel msg;
+ int ret;
+
+ memset(&msg, 0, sizeof(msg));
+ msg.header.msgtype = CHANNELMSG_MODIFYCHANNEL;
+ msg.child_relid = channel->offermsg.child_relid;
+ msg.target_vp = target_vp;
+
+ ret = vmbus_post_msg(&msg, sizeof(msg), true);
+ trace_vmbus_send_modifychannel(&msg, ret);
+
+ return ret;
+}
+
+static int send_modifychannel_with_ack(struct vmbus_channel *channel, u32 target_vp)
+{
+ struct vmbus_channel_modifychannel *msg;
+ struct vmbus_channel_msginfo *info;
+ unsigned long flags;
+ int ret;
+
+ info = kzalloc(sizeof(struct vmbus_channel_msginfo) +
+ sizeof(struct vmbus_channel_modifychannel),
+ GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ init_completion(&info->waitevent);
+ info->waiting_channel = channel;
+
+ msg = (struct vmbus_channel_modifychannel *)info->msg;
+ msg->header.msgtype = CHANNELMSG_MODIFYCHANNEL;
+ msg->child_relid = channel->offermsg.child_relid;
+ msg->target_vp = target_vp;
+
+ spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+ list_add_tail(&info->msglistentry, &vmbus_connection.chn_msg_list);
+ spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+ ret = vmbus_post_msg(msg, sizeof(*msg), true);
+ trace_vmbus_send_modifychannel(msg, ret);
+ if (ret != 0) {
+ spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+ list_del(&info->msglistentry);
+ spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+ goto free_info;
+ }
+
+ /*
+ * Release channel_mutex; otherwise, vmbus_onoffer_rescind() could block on
+ * the mutex and be unable to signal the completion.
+ *
+ * See the caller target_cpu_store() for information about the usage of the
+ * mutex.
+ */
+ mutex_unlock(&vmbus_connection.channel_mutex);
+ wait_for_completion(&info->waitevent);
+ mutex_lock(&vmbus_connection.channel_mutex);
+
+ spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+ list_del(&info->msglistentry);
+ spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+ if (info->response.modify_response.status)
+ ret = -EAGAIN;
+
+free_info:
+ kfree(info);
+ return ret;
+}
+
/*
* Set/change the vCPU (@target_vp) the channel (@child_relid) will interrupt.
*
- * CHANNELMSG_MODIFYCHANNEL messages are aynchronous. Also, Hyper-V does not
- * ACK such messages. IOW we can't know when the host will stop interrupting
- * the "old" vCPU and start interrupting the "new" vCPU for the given channel.
+ * CHANNELMSG_MODIFYCHANNEL messages are aynchronous. When VMbus version 5.3
+ * or later is negotiated, Hyper-V always sends an ACK in response to such a
+ * message. For VMbus version 5.2 and earlier, it never sends an ACK. With-
+ * out an ACK, we can not know when the host will stop interrupting the "old"
+ * vCPU and start interrupting the "new" vCPU for the given channel.
*
* The CHANNELMSG_MODIFYCHANNEL message type is supported since VMBus version
* VERSION_WIN10_V4_1.
*/
-int vmbus_send_modifychannel(u32 child_relid, u32 target_vp)
+int vmbus_send_modifychannel(struct vmbus_channel *channel, u32 target_vp)
{
- struct vmbus_channel_modifychannel conn_msg;
- int ret;
-
- memset(&conn_msg, 0, sizeof(conn_msg));
- conn_msg.header.msgtype = CHANNELMSG_MODIFYCHANNEL;
- conn_msg.child_relid = child_relid;
- conn_msg.target_vp = target_vp;
-
- ret = vmbus_post_msg(&conn_msg, sizeof(conn_msg), true);
-
- trace_vmbus_send_modifychannel(&conn_msg, ret);
-
- return ret;
+ if (vmbus_proto_version >= VERSION_WIN10_V5_3)
+ return send_modifychannel_with_ack(channel, target_vp);
+ return send_modifychannel_without_ack(channel, target_vp);
}
EXPORT_SYMBOL_GPL(vmbus_send_modifychannel);
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index f3cf4af01e102..4c9e45d1f462c 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -1311,6 +1311,46 @@ static void vmbus_ongpadl_created(struct vmbus_channel_message_header *hdr)
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
}
+/*
+ * vmbus_onmodifychannel_response - Modify Channel response handler.
+ *
+ * This is invoked when we received a response to our channel modify request.
+ * Find the matching request, copy the response and signal the requesting thread.
+ */
+static void vmbus_onmodifychannel_response(struct vmbus_channel_message_header *hdr)
+{
+ struct vmbus_channel_modifychannel_response *response;
+ struct vmbus_channel_msginfo *msginfo;
+ unsigned long flags;
+
+ response = (struct vmbus_channel_modifychannel_response *)hdr;
+
+ trace_vmbus_onmodifychannel_response(response);
+
+ /*
+ * Find the modify msg, copy the response and signal/unblock the wait event.
+ */
+ spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+
+ list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list, msglistentry) {
+ struct vmbus_channel_message_header *responseheader =
+ (struct vmbus_channel_message_header *)msginfo->msg;
+
+ if (responseheader->msgtype == CHANNELMSG_MODIFYCHANNEL) {
+ struct vmbus_channel_modifychannel *modifymsg;
+
+ modifymsg = (struct vmbus_channel_modifychannel *)msginfo->msg;
+ if (modifymsg->child_relid == response->child_relid) {
+ memcpy(&msginfo->response.modify_response, response,
+ sizeof(*response));
+ complete(&msginfo->waitevent);
+ break;
+ }
+ }
+ }
+ spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+}
+
/*
* vmbus_ongpadl_torndown - GPADL torndown handler.
*
@@ -1428,6 +1468,8 @@ channel_message_table[CHANNELMSG_COUNT] = {
{ CHANNELMSG_TL_CONNECT_REQUEST, 0, NULL, 0},
{ CHANNELMSG_MODIFYCHANNEL, 0, NULL, 0},
{ CHANNELMSG_TL_CONNECT_RESULT, 0, NULL, 0},
+ { CHANNELMSG_MODIFYCHANNEL_RESPONSE, 1, vmbus_onmodifychannel_response,
+ sizeof(struct vmbus_channel_modifychannel_response)},
};
/*
diff --git a/drivers/hv/hv_trace.h b/drivers/hv/hv_trace.h
index 6063bb21bb137..c02a1719e92f2 100644
--- a/drivers/hv/hv_trace.h
+++ b/drivers/hv/hv_trace.h
@@ -103,6 +103,21 @@ TRACE_EVENT(vmbus_ongpadl_created,
)
);
+TRACE_EVENT(vmbus_onmodifychannel_response,
+ TP_PROTO(const struct vmbus_channel_modifychannel_response *response),
+ TP_ARGS(response),
+ TP_STRUCT__entry(
+ __field(u32, child_relid)
+ __field(u32, status)
+ ),
+ TP_fast_assign(__entry->child_relid = response->child_relid;
+ __entry->status = response->status;
+ ),
+ TP_printk("child_relid 0x%x, status %d",
+ __entry->child_relid, __entry->status
+ )
+ );
+
TRACE_EVENT(vmbus_ongpadl_torndown,
TP_PROTO(const struct vmbus_channel_gpadl_torndown *gpadltorndown),
TP_ARGS(gpadltorndown),
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 51c40d5e3c8ac..b12d6827b222b 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1848,13 +1848,15 @@ static ssize_t target_cpu_store(struct vmbus_channel *channel,
if (target_cpu == origin_cpu)
goto cpu_store_unlock;
- if (vmbus_send_modifychannel(channel->offermsg.child_relid,
+ if (vmbus_send_modifychannel(channel,
hv_cpu_number_to_vp_number(target_cpu))) {
ret = -EIO;
goto cpu_store_unlock;
}
/*
+ * For version before VERSION_WIN10_V5_3, the following warning holds:
+ *
* Warning. At this point, there is *no* guarantee that the host will
* have successfully processed the vmbus_send_modifychannel() request.
* See the header comment of vmbus_send_modifychannel() for more info.
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index d6a6f76040b5f..876003512d4d2 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -477,6 +477,7 @@ enum vmbus_channel_message_type {
CHANNELMSG_TL_CONNECT_REQUEST = 21,
CHANNELMSG_MODIFYCHANNEL = 22,
CHANNELMSG_TL_CONNECT_RESULT = 23,
+ CHANNELMSG_MODIFYCHANNEL_RESPONSE = 24,
CHANNELMSG_COUNT
};
@@ -590,6 +591,13 @@ struct vmbus_channel_open_result {
u32 status;
} __packed;
+/* Modify Channel Result parameters */
+struct vmbus_channel_modifychannel_response {
+ struct vmbus_channel_message_header header;
+ u32 child_relid;
+ u32 status;
+} __packed;
+
/* Close channel parameters; */
struct vmbus_channel_close_channel {
struct vmbus_channel_message_header header;
@@ -722,6 +730,7 @@ struct vmbus_channel_msginfo {
struct vmbus_channel_gpadl_torndown gpadl_torndown;
struct vmbus_channel_gpadl_created gpadl_created;
struct vmbus_channel_version_response version_response;
+ struct vmbus_channel_modifychannel_response modify_response;
} response;
u32 msgsize;
@@ -1596,7 +1605,7 @@ extern __u32 vmbus_proto_version;
int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id,
const guid_t *shv_host_servie_id);
-int vmbus_send_modifychannel(u32 child_relid, u32 target_vp);
+int vmbus_send_modifychannel(struct vmbus_channel *channel, u32 target_vp);
void vmbus_set_event(struct vmbus_channel *channel);
/* Get the start of the ring buffer. */
--
2.25.1
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