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From:   Dexuan Cui <decui@microsoft.com>
To:     KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
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        Michael Kelley <mikelley@microsoft.com>,
        vkuznets <vkuznets@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 4/4] hv_utils: Add the support of hibernation
Thread-Topic: [PATCH v2 4/4] hv_utils: Add the support of hibernation
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Date:   Mon, 13 Jan 2020 06:32:22 +0000
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Add util_pre_suspend() and util_pre_resume() for some hv_utils devices
(e.g. kvp/vss/fcopy), because they need special handling before
util_suspend() calls vmbus_close().

For kvp, all the possible pending work items should be cancelled.

For vss and fcopy, extra clean-up needs to be done, i.e. fake a THAW
message for hv_vss_daemon and fake a CANCEL_FCOPY message for
hv_fcopy_daemonemon, otherwise when the VM resums back, the daemons
can end up in an inconsistent state (i.e. the file systems are
frozen but will never be thawed; the file transmitted via fcopy
may not be complete). Note: there is an extra patch for the daemons:
"Tools: hv: Reopen the devices if read() or write() returns errors",
because the hv_utils driver can not guarantee the whole transaction
finishes completely once util_suspend() starts to run (at this time,
all the userspace processes are frozen).

util_probe() disables channel->callback_event to avoid the race with
the the channel callback.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/hv/hv_fcopy.c     | 58 ++++++++++++++++++++++++++++++++++++-
 drivers/hv/hv_kvp.c       | 44 ++++++++++++++++++++++++++--
 drivers/hv/hv_snapshot.c  | 60 +++++++++++++++++++++++++++++++++++++--
 drivers/hv/hv_util.c      | 60 ++++++++++++++++++++++++++++++++++++++-
 drivers/hv/hyperv_vmbus.h |  6 ++++
 include/linux/hyperv.h    |  2 ++
 6 files changed, 224 insertions(+), 6 deletions(-)

diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index 08fa4a5de644..d63853f16356 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -346,9 +346,65 @@ int hv_fcopy_init(struct hv_util_service *srv)
 	return 0;
 }
=20
+static void hv_fcopy_cancel_work(void)
+{
+	cancel_delayed_work_sync(&fcopy_timeout_work);
+	cancel_work_sync(&fcopy_send_work);
+}
+
+int hv_fcopy_pre_suspend(void)
+{
+	struct vmbus_channel *channel =3D fcopy_transaction.recv_channel;
+	struct hv_fcopy_hdr *fcopy_msg;
+
+	tasklet_disable(&channel->callback_event);
+
+	/*
+	 * Fake a CANCEL_FCOPY message to the user space daemon in case the
+	 * daemon is in the middle of copying some file. It doesn't matter if
+	 * there is already a message pending to be delivered to the user
+	 * space: we force fcopy_transaction.state to be HVUTIL_READY, so the
+	 * user space daemon's write() will fail with -EINVAL (see
+	 * fcopy_on_msg()), and the daemon will reset the device by closing and
+	 * re-opening it.
+	 */
+	fcopy_msg =3D kzalloc(sizeof(*fcopy_msg), GFP_KERNEL);
+	if (!fcopy_msg)
+		goto err;
+
+	fcopy_msg->operation =3D CANCEL_FCOPY;
+
+	hv_fcopy_cancel_work();
+
+	/* We don't care about the return value. */
+	hvutil_transport_send(hvt, fcopy_msg, sizeof(*fcopy_msg), NULL);
+
+	kfree(fcopy_msg);
+
+	fcopy_transaction.state =3D HVUTIL_READY;
+
+	/* tasklet_enable() will be called in hv_fcopy_pre_resume(). */
+
+	return 0;
+err:
+	tasklet_enable(&channel->callback_event);
+	return -ENOMEM;
+}
+
+int hv_fcopy_pre_resume(void)
+{
+	struct vmbus_channel *channel =3D fcopy_transaction.recv_channel;
+
+	tasklet_enable(&channel->callback_event);
+
+	return 0;
+}
+
 void hv_fcopy_deinit(void)
 {
 	fcopy_transaction.state =3D HVUTIL_DEVICE_DYING;
-	cancel_delayed_work_sync(&fcopy_timeout_work);
+
+	hv_fcopy_cancel_work();
+
 	hvutil_transport_destroy(hvt);
 }
diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index ae7c028dc5a8..ca03f68df5d0 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -758,11 +758,51 @@ hv_kvp_init(struct hv_util_service *srv)
 	return 0;
 }
=20
-void hv_kvp_deinit(void)
+static void hv_kvp_cancel_work(void)
 {
-	kvp_transaction.state =3D HVUTIL_DEVICE_DYING;
 	cancel_delayed_work_sync(&kvp_host_handshake_work);
 	cancel_delayed_work_sync(&kvp_timeout_work);
 	cancel_work_sync(&kvp_sendkey_work);
+}
+
+int hv_kvp_pre_suspend(void)
+{
+	struct vmbus_channel *channel =3D kvp_transaction.recv_channel;
+
+	tasklet_disable(&channel->callback_event);
+
+	/*
+	 * If there is a pending transtion, it's unnecessary to tell the host
+	 * that the tranction will fail, becasue that is implied when
+	 * util_suspend() calls vmbus_close() later.
+	 */
+	hv_kvp_cancel_work();
+
+	/*
+	 * Forece the state to READY to handle the ICMSGTYPE_NEGOTIATE message
+	 * later. The user space daemon may go out of order and its write()
+	 * may get an EINVAL error: this doesn't matter since the daemon will
+	 * reset the device by closing and re-opening the device.
+	 */
+	kvp_transaction.state =3D HVUTIL_READY;
+
+	return 0;
+}
+
+int hv_kvp_pre_resume(void)
+{
+	struct vmbus_channel *channel =3D kvp_transaction.recv_channel;
+
+	tasklet_enable(&channel->callback_event);
+
+	return 0;
+}
+
+void hv_kvp_deinit(void)
+{
+	kvp_transaction.state =3D HVUTIL_DEVICE_DYING;
+
+	hv_kvp_cancel_work();
+
 	hvutil_transport_destroy(hvt);
 }
diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index 03b6454268b3..eb766ff8841b 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -229,6 +229,7 @@ static void vss_handle_request(struct work_struct *dumm=
y)
 		vss_transaction.state =3D HVUTIL_HOSTMSG_RECEIVED;
 		vss_send_op();
 		return;
+
 	case VSS_OP_GET_DM_INFO:
 		vss_transaction.msg->dm_info.flags =3D 0;
 		break;
@@ -379,10 +380,65 @@ hv_vss_init(struct hv_util_service *srv)
 	return 0;
 }
=20
-void hv_vss_deinit(void)
+static void hv_vss_cancel_work(void)
 {
-	vss_transaction.state =3D HVUTIL_DEVICE_DYING;
 	cancel_delayed_work_sync(&vss_timeout_work);
 	cancel_work_sync(&vss_handle_request_work);
+}
+
+int hv_vss_pre_suspend(void)
+{
+	struct vmbus_channel *channel =3D vss_transaction.recv_channel;
+	struct hv_vss_msg *vss_msg;
+
+	tasklet_disable(&channel->callback_event);
+
+	/*
+	 * Fake a THAW message for the user space daemon in case the daemon
+	 * has frozen the file systems. It doesn't matter if there is already
+	 * a message pending to be delivered to the user space: we force
+	 * vss_transaction.state to be HVUTIL_READY, so the user space daemon's
+	 * write() will fail with -EINVAL (see vss_on_msg()), and the daemon
+	 * will reset the device by closing and re-opening it.
+	 */
+	vss_msg =3D kzalloc(sizeof(*vss_msg), GFP_KERNEL);
+	if (!vss_msg)
+		goto err;
+
+	vss_msg->vss_hdr.operation =3D VSS_OP_THAW;
+
+	/* Cancel any possible pending work. */
+	hv_vss_cancel_work();
+
+	/* We don't care about the return value. */
+	hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
+
+	kfree(vss_msg);
+
+	vss_transaction.state =3D HVUTIL_READY;
+
+	/* tasklet_enable() will be called in hv_vss_pre_resume(). */
+
+	return 0;
+err:
+	tasklet_enable(&channel->callback_event);
+	return -ENOMEM;
+}
+
+int hv_vss_pre_resume(void)
+{
+	struct vmbus_channel *channel =3D vss_transaction.recv_channel;
+
+	tasklet_enable(&channel->callback_event);
+
+	return 0;
+}
+
+void hv_vss_deinit(void)
+{
+	vss_transaction.state =3D HVUTIL_DEVICE_DYING;
+
+	hv_vss_cancel_work();
+
 	hvutil_transport_destroy(hvt);
 }
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index d5216af62788..255faa3d657c 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -123,12 +123,14 @@ static struct hv_util_service util_shutdown =3D {
 };
=20
 static int hv_timesync_init(struct hv_util_service *srv);
+static int hv_timesync_pre_suspend(void);
 static void hv_timesync_deinit(void);
=20
 static void timesync_onchannelcallback(void *context);
 static struct hv_util_service util_timesynch =3D {
 	.util_cb =3D timesync_onchannelcallback,
 	.util_init =3D hv_timesync_init,
+	.util_pre_suspend =3D hv_timesync_pre_suspend,
 	.util_deinit =3D hv_timesync_deinit,
 };
=20
@@ -140,18 +142,24 @@ static struct hv_util_service util_heartbeat =3D {
 static struct hv_util_service util_kvp =3D {
 	.util_cb =3D hv_kvp_onchannelcallback,
 	.util_init =3D hv_kvp_init,
+	.util_pre_suspend =3D hv_kvp_pre_suspend,
+	.util_pre_resume =3D hv_kvp_pre_resume,
 	.util_deinit =3D hv_kvp_deinit,
 };
=20
 static struct hv_util_service util_vss =3D {
 	.util_cb =3D hv_vss_onchannelcallback,
 	.util_init =3D hv_vss_init,
+	.util_pre_suspend =3D hv_vss_pre_suspend,
+	.util_pre_resume =3D hv_vss_pre_resume,
 	.util_deinit =3D hv_vss_deinit,
 };
=20
 static struct hv_util_service util_fcopy =3D {
 	.util_cb =3D hv_fcopy_onchannelcallback,
 	.util_init =3D hv_fcopy_init,
+	.util_pre_suspend =3D hv_fcopy_pre_suspend,
+	.util_pre_resume =3D hv_fcopy_pre_resume,
 	.util_deinit =3D hv_fcopy_deinit,
 };
=20
@@ -512,6 +520,41 @@ static int util_remove(struct hv_device *dev)
 	return 0;
 }
=20
+static int util_suspend(struct hv_device *dev)
+{
+	struct hv_util_service *srv =3D hv_get_drvdata(dev);
+	int ret =3D 0;
+
+	if (srv->util_pre_suspend) {
+		ret =3D srv->util_pre_suspend();
+
+		if (ret)
+			return ret;
+	}
+
+	vmbus_close(dev->channel);
+
+	return 0;
+}
+
+static int util_resume(struct hv_device *dev)
+{
+	struct hv_util_service *srv =3D hv_get_drvdata(dev);
+	int ret =3D 0;
+
+	if (srv->util_pre_resume) {
+		ret =3D srv->util_pre_resume();
+
+		if (ret)
+			return ret;
+	}
+
+	ret =3D vmbus_open(dev->channel, 4 * HV_HYP_PAGE_SIZE,
+			 4 * HV_HYP_PAGE_SIZE, NULL, 0, srv->util_cb,
+			 dev->channel);
+	return ret;
+}
+
 static const struct hv_vmbus_device_id id_table[] =3D {
 	/* Shutdown guid */
 	{ HV_SHUTDOWN_GUID,
@@ -548,6 +591,8 @@ static  struct hv_driver util_drv =3D {
 	.id_table =3D id_table,
 	.probe =3D  util_probe,
 	.remove =3D  util_remove,
+	.suspend =3D util_suspend,
+	.resume =3D  util_resume,
 	.driver =3D {
 		.probe_type =3D PROBE_PREFER_ASYNCHRONOUS,
 	},
@@ -617,11 +662,24 @@ static int hv_timesync_init(struct hv_util_service *s=
rv)
 	return 0;
 }
=20
+static void hv_timesync_cancel_work(void)
+{
+	cancel_work_sync(&adj_time_work);
+}
+
+static int hv_timesync_pre_suspend(void)
+{
+	hv_timesync_cancel_work();
+
+	return 0;
+}
+
 static void hv_timesync_deinit(void)
 {
 	if (hv_ptp_clock)
 		ptp_clock_unregister(hv_ptp_clock);
-	cancel_work_sync(&adj_time_work);
+
+	hv_timesync_cancel_work();
 }
=20
 static int __init init_hyperv_utils(void)
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 20edcfd3b96c..f5fa3b3c9baf 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -352,14 +352,20 @@ void vmbus_on_msg_dpc(unsigned long data);
=20
 int hv_kvp_init(struct hv_util_service *srv);
 void hv_kvp_deinit(void);
+int hv_kvp_pre_suspend(void);
+int hv_kvp_pre_resume(void);
 void hv_kvp_onchannelcallback(void *context);
=20
 int hv_vss_init(struct hv_util_service *srv);
 void hv_vss_deinit(void);
+int hv_vss_pre_suspend(void);
+int hv_vss_pre_resume(void);
 void hv_vss_onchannelcallback(void *context);
=20
 int hv_fcopy_init(struct hv_util_service *srv);
 void hv_fcopy_deinit(void);
+int hv_fcopy_pre_suspend(void);
+int hv_fcopy_pre_resume(void);
 void hv_fcopy_onchannelcallback(void *context);
 void vmbus_initiate_unload(bool crash);
=20
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 41c58011431e..692c89ccf5df 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1435,6 +1435,8 @@ struct hv_util_service {
 	void (*util_cb)(void *);
 	int (*util_init)(struct hv_util_service *);
 	void (*util_deinit)(void);
+	int (*util_pre_suspend)(void);
+	int (*util_pre_resume)(void);
 };
=20
 struct vmbuspipe_hdr {
--=20
2.19.1