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* [PATCH v4 0/3] virtio-balloon: tweak config_changed
@ 2019-01-08  4:50 ` Wei Wang
  0 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

Since virtio-ccw doesn't work with accessing to the config space
inside an interrupt context, this patch series avoids that issue by
moving the config register accesses to the related workqueue contexts.

v3->v4 ChangeLog:
    - change virtio32_to_cpu to cpu_to_virtio_32 in send_cmd_id_start;
v2->v3 ChangeLog:
    - rename cmd_id_received to cmd_id_received_cache, and have call sites
      read the latest value via virtio_balloon_cmd_id_received. (Still
      kept Cornelia and Halil's reviewed-by as it's a minor change)
    - remove zeroing vb->num_free_page_blocks in probe since vb is
      allocated via kzalloc.
v1->v2 ChangeLog:
    - add config_read_bitmap to indicate to the workqueue callbacks about
      the necessity of reading the related config fields.

Wei Wang (3):
  virtio-balloon: tweak config_changed implementation
  virtio-balloon: improve update_balloon_size_func
  virtio_balloon: remove the unnecessary 0-initialization

 drivers/virtio/virtio_balloon.c | 104 ++++++++++++++++++++++++++--------------
 1 file changed, 69 insertions(+), 35 deletions(-)

-- 
2.7.4


^ permalink raw reply	[flat|nested] 20+ messages in thread
* [virtio-dev] [PATCH v4 0/3] virtio-balloon: tweak config_changed
@ 2019-01-08  4:50 ` Wei Wang
  0 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

Since virtio-ccw doesn't work with accessing to the config space
inside an interrupt context, this patch series avoids that issue by
moving the config register accesses to the related workqueue contexts.

v3->v4 ChangeLog:
    - change virtio32_to_cpu to cpu_to_virtio_32 in send_cmd_id_start;
v2->v3 ChangeLog:
    - rename cmd_id_received to cmd_id_received_cache, and have call sites
      read the latest value via virtio_balloon_cmd_id_received. (Still
      kept Cornelia and Halil's reviewed-by as it's a minor change)
    - remove zeroing vb->num_free_page_blocks in probe since vb is
      allocated via kzalloc.
v1->v2 ChangeLog:
    - add config_read_bitmap to indicate to the workqueue callbacks about
      the necessity of reading the related config fields.

Wei Wang (3):
  virtio-balloon: tweak config_changed implementation
  virtio-balloon: improve update_balloon_size_func
  virtio_balloon: remove the unnecessary 0-initialization

 drivers/virtio/virtio_balloon.c | 104 ++++++++++++++++++++++++++--------------
 1 file changed, 69 insertions(+), 35 deletions(-)

-- 
2.7.4


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^ permalink raw reply	[flat|nested] 20+ messages in thread
* [PATCH v4 1/3] virtio-balloon: tweak config_changed implementation
  2019-01-08  4:50 ` [virtio-dev] " Wei Wang
@ 2019-01-08  4:50   ` Wei Wang
  -1 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

virtio-ccw has deadlock issues with reading the config space inside the
interrupt context, so we tweak the virtballoon_changed implementation
by moving the config read operations into the related workqueue contexts.
The config_read_bitmap is used as a flag to the workqueue callbacks
about the related config fields that need to be read.

The cmd_id_received is also renamed to cmd_id_received_cache, and
the value should be obtained via virtio_balloon_cmd_id_received.

Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 drivers/virtio/virtio_balloon.c | 98 +++++++++++++++++++++++++++--------------
 1 file changed, 65 insertions(+), 33 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 728ecd1..45d32f5 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -61,6 +61,10 @@ enum virtio_balloon_vq {
 	VIRTIO_BALLOON_VQ_MAX
 };
 
+enum virtio_balloon_config_read {
+	VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
+};
+
 struct virtio_balloon {
 	struct virtio_device *vdev;
 	struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
@@ -77,14 +81,20 @@ struct virtio_balloon {
 	/* Prevent updating balloon when it is being canceled. */
 	spinlock_t stop_update_lock;
 	bool stop_update;
+	/* Bitmap to indicate if reading the related config fields are needed */
+	unsigned long config_read_bitmap;
 
 	/* The list of allocated free pages, waiting to be given back to mm */
 	struct list_head free_page_list;
 	spinlock_t free_page_list_lock;
 	/* The number of free page blocks on the above list */
 	unsigned long num_free_page_blocks;
-	/* The cmd id received from host */
-	u32 cmd_id_received;
+	/*
+	 * The cmd id received from host.
+	 * Read it via virtio_balloon_cmd_id_received to get the latest value
+	 * sent from host.
+	 */
+	u32 cmd_id_received_cache;
 	/* The cmd id that is actively in use */
 	__virtio32 cmd_id_active;
 	/* Buffer to store the stop sign */
@@ -390,37 +400,31 @@ static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb,
 	return num_returned;
 }
 
+static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)
+{
+	if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		return;
+
+	/* No need to queue the work if the bit was already set. */
+	if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			     &vb->config_read_bitmap))
+		return;
+
+	queue_work(vb->balloon_wq, &vb->report_free_page_work);
+}
+
 static void virtballoon_changed(struct virtio_device *vdev)
 {
 	struct virtio_balloon *vb = vdev->priv;
 	unsigned long flags;
-	s64 diff = towards_target(vb);
-
-	if (diff) {
-		spin_lock_irqsave(&vb->stop_update_lock, flags);
-		if (!vb->stop_update)
-			queue_work(system_freezable_wq,
-				   &vb->update_balloon_size_work);
-		spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-	}
 
-	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
-		virtio_cread(vdev, struct virtio_balloon_config,
-			     free_page_report_cmd_id, &vb->cmd_id_received);
-		if (vb->cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
-			/* Pass ULONG_MAX to give back all the free pages */
-			return_free_pages_to_mm(vb, ULONG_MAX);
-		} else if (vb->cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
-			   vb->cmd_id_received !=
-			   virtio32_to_cpu(vdev, vb->cmd_id_active)) {
-			spin_lock_irqsave(&vb->stop_update_lock, flags);
-			if (!vb->stop_update) {
-				queue_work(vb->balloon_wq,
-					   &vb->report_free_page_work);
-			}
-			spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-		}
+	spin_lock_irqsave(&vb->stop_update_lock, flags);
+	if (!vb->stop_update) {
+		queue_work(system_freezable_wq,
+			   &vb->update_balloon_size_work);
+		virtio_balloon_queue_free_page_work(vb);
 	}
+	spin_unlock_irqrestore(&vb->stop_update_lock, flags);
 }
 
 static void update_balloon_size(struct virtio_balloon *vb)
@@ -527,6 +531,17 @@ static int init_vqs(struct virtio_balloon *vb)
 	return 0;
 }
 
+static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
+{
+	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			       &vb->config_read_bitmap))
+		virtio_cread(vb->vdev, struct virtio_balloon_config,
+			     free_page_report_cmd_id,
+			     &vb->cmd_id_received_cache);
+
+	return vb->cmd_id_received_cache;
+}
+
 static int send_cmd_id_start(struct virtio_balloon *vb)
 {
 	struct scatterlist sg;
@@ -537,7 +552,8 @@ static int send_cmd_id_start(struct virtio_balloon *vb)
 	while (virtqueue_get_buf(vq, &unused))
 		;
 
-	vb->cmd_id_active = cpu_to_virtio32(vb->vdev, vb->cmd_id_received);
+	vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
+					virtio_balloon_cmd_id_received(vb));
 	sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));
 	err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);
 	if (!err)
@@ -620,7 +636,8 @@ static int send_free_pages(struct virtio_balloon *vb)
 		 * stop the reporting.
 		 */
 		cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);
-		if (cmd_id_active != vb->cmd_id_received)
+		if (unlikely(cmd_id_active !=
+			     virtio_balloon_cmd_id_received(vb)))
 			break;
 
 		/*
@@ -637,11 +654,9 @@ static int send_free_pages(struct virtio_balloon *vb)
 	return 0;
 }
 
-static void report_free_page_func(struct work_struct *work)
+static void virtio_balloon_report_free_page(struct virtio_balloon *vb)
 {
 	int err;
-	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
-						 report_free_page_work);
 	struct device *dev = &vb->vdev->dev;
 
 	/* Start by sending the received cmd id to host with an outbuf. */
@@ -659,6 +674,23 @@ static void report_free_page_func(struct work_struct *work)
 		dev_err(dev, "Failed to send a stop id, err = %d\n", err);
 }
 
+static void report_free_page_func(struct work_struct *work)
+{
+	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
+						 report_free_page_work);
+	u32 cmd_id_received;
+
+	cmd_id_received = virtio_balloon_cmd_id_received(vb);
+	if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
+		/* Pass ULONG_MAX to give back all the free pages */
+		return_free_pages_to_mm(vb, ULONG_MAX);
+	} else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
+		   cmd_id_received !=
+		   virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {
+		virtio_balloon_report_free_page(vb);
+	}
+}
+
 #ifdef CONFIG_BALLOON_COMPACTION
 /*
  * virtballoon_migratepage - perform the balloon page migration on behalf of
@@ -885,7 +917,7 @@ static int virtballoon_probe(struct virtio_device *vdev)
 			goto out_del_vqs;
 		}
 		INIT_WORK(&vb->report_free_page_work, report_free_page_func);
-		vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP;
+		vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
 		vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
 						  VIRTIO_BALLOON_CMD_ID_STOP);
 		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [PATCH v4 1/3] virtio-balloon: tweak config_changed implementation
  2019-01-08  4:50 ` [virtio-dev] " Wei Wang
  (?)
@ 2019-01-08  4:50 ` Wei Wang
  -1 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: pasic, dgilbert, pbonzini

virtio-ccw has deadlock issues with reading the config space inside the
interrupt context, so we tweak the virtballoon_changed implementation
by moving the config read operations into the related workqueue contexts.
The config_read_bitmap is used as a flag to the workqueue callbacks
about the related config fields that need to be read.

The cmd_id_received is also renamed to cmd_id_received_cache, and
the value should be obtained via virtio_balloon_cmd_id_received.

Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 drivers/virtio/virtio_balloon.c | 98 +++++++++++++++++++++++++++--------------
 1 file changed, 65 insertions(+), 33 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 728ecd1..45d32f5 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -61,6 +61,10 @@ enum virtio_balloon_vq {
 	VIRTIO_BALLOON_VQ_MAX
 };
 
+enum virtio_balloon_config_read {
+	VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
+};
+
 struct virtio_balloon {
 	struct virtio_device *vdev;
 	struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
@@ -77,14 +81,20 @@ struct virtio_balloon {
 	/* Prevent updating balloon when it is being canceled. */
 	spinlock_t stop_update_lock;
 	bool stop_update;
+	/* Bitmap to indicate if reading the related config fields are needed */
+	unsigned long config_read_bitmap;
 
 	/* The list of allocated free pages, waiting to be given back to mm */
 	struct list_head free_page_list;
 	spinlock_t free_page_list_lock;
 	/* The number of free page blocks on the above list */
 	unsigned long num_free_page_blocks;
-	/* The cmd id received from host */
-	u32 cmd_id_received;
+	/*
+	 * The cmd id received from host.
+	 * Read it via virtio_balloon_cmd_id_received to get the latest value
+	 * sent from host.
+	 */
+	u32 cmd_id_received_cache;
 	/* The cmd id that is actively in use */
 	__virtio32 cmd_id_active;
 	/* Buffer to store the stop sign */
@@ -390,37 +400,31 @@ static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb,
 	return num_returned;
 }
 
+static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)
+{
+	if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		return;
+
+	/* No need to queue the work if the bit was already set. */
+	if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			     &vb->config_read_bitmap))
+		return;
+
+	queue_work(vb->balloon_wq, &vb->report_free_page_work);
+}
+
 static void virtballoon_changed(struct virtio_device *vdev)
 {
 	struct virtio_balloon *vb = vdev->priv;
 	unsigned long flags;
-	s64 diff = towards_target(vb);
-
-	if (diff) {
-		spin_lock_irqsave(&vb->stop_update_lock, flags);
-		if (!vb->stop_update)
-			queue_work(system_freezable_wq,
-				   &vb->update_balloon_size_work);
-		spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-	}
 
-	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
-		virtio_cread(vdev, struct virtio_balloon_config,
-			     free_page_report_cmd_id, &vb->cmd_id_received);
-		if (vb->cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
-			/* Pass ULONG_MAX to give back all the free pages */
-			return_free_pages_to_mm(vb, ULONG_MAX);
-		} else if (vb->cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
-			   vb->cmd_id_received !=
-			   virtio32_to_cpu(vdev, vb->cmd_id_active)) {
-			spin_lock_irqsave(&vb->stop_update_lock, flags);
-			if (!vb->stop_update) {
-				queue_work(vb->balloon_wq,
-					   &vb->report_free_page_work);
-			}
-			spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-		}
+	spin_lock_irqsave(&vb->stop_update_lock, flags);
+	if (!vb->stop_update) {
+		queue_work(system_freezable_wq,
+			   &vb->update_balloon_size_work);
+		virtio_balloon_queue_free_page_work(vb);
 	}
+	spin_unlock_irqrestore(&vb->stop_update_lock, flags);
 }
 
 static void update_balloon_size(struct virtio_balloon *vb)
@@ -527,6 +531,17 @@ static int init_vqs(struct virtio_balloon *vb)
 	return 0;
 }
 
+static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
+{
+	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			       &vb->config_read_bitmap))
+		virtio_cread(vb->vdev, struct virtio_balloon_config,
+			     free_page_report_cmd_id,
+			     &vb->cmd_id_received_cache);
+
+	return vb->cmd_id_received_cache;
+}
+
 static int send_cmd_id_start(struct virtio_balloon *vb)
 {
 	struct scatterlist sg;
@@ -537,7 +552,8 @@ static int send_cmd_id_start(struct virtio_balloon *vb)
 	while (virtqueue_get_buf(vq, &unused))
 		;
 
-	vb->cmd_id_active = cpu_to_virtio32(vb->vdev, vb->cmd_id_received);
+	vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
+					virtio_balloon_cmd_id_received(vb));
 	sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));
 	err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);
 	if (!err)
@@ -620,7 +636,8 @@ static int send_free_pages(struct virtio_balloon *vb)
 		 * stop the reporting.
 		 */
 		cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);
-		if (cmd_id_active != vb->cmd_id_received)
+		if (unlikely(cmd_id_active !=
+			     virtio_balloon_cmd_id_received(vb)))
 			break;
 
 		/*
@@ -637,11 +654,9 @@ static int send_free_pages(struct virtio_balloon *vb)
 	return 0;
 }
 
-static void report_free_page_func(struct work_struct *work)
+static void virtio_balloon_report_free_page(struct virtio_balloon *vb)
 {
 	int err;
-	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
-						 report_free_page_work);
 	struct device *dev = &vb->vdev->dev;
 
 	/* Start by sending the received cmd id to host with an outbuf. */
@@ -659,6 +674,23 @@ static void report_free_page_func(struct work_struct *work)
 		dev_err(dev, "Failed to send a stop id, err = %d\n", err);
 }
 
+static void report_free_page_func(struct work_struct *work)
+{
+	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
+						 report_free_page_work);
+	u32 cmd_id_received;
+
+	cmd_id_received = virtio_balloon_cmd_id_received(vb);
+	if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
+		/* Pass ULONG_MAX to give back all the free pages */
+		return_free_pages_to_mm(vb, ULONG_MAX);
+	} else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
+		   cmd_id_received !=
+		   virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {
+		virtio_balloon_report_free_page(vb);
+	}
+}
+
 #ifdef CONFIG_BALLOON_COMPACTION
 /*
  * virtballoon_migratepage - perform the balloon page migration on behalf of
@@ -885,7 +917,7 @@ static int virtballoon_probe(struct virtio_device *vdev)
 			goto out_del_vqs;
 		}
 		INIT_WORK(&vb->report_free_page_work, report_free_page_func);
-		vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP;
+		vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
 		vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
 						  VIRTIO_BALLOON_CMD_ID_STOP);
 		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [virtio-dev] [PATCH v4 1/3] virtio-balloon: tweak config_changed implementation
@ 2019-01-08  4:50   ` Wei Wang
  0 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

virtio-ccw has deadlock issues with reading the config space inside the
interrupt context, so we tweak the virtballoon_changed implementation
by moving the config read operations into the related workqueue contexts.
The config_read_bitmap is used as a flag to the workqueue callbacks
about the related config fields that need to be read.

The cmd_id_received is also renamed to cmd_id_received_cache, and
the value should be obtained via virtio_balloon_cmd_id_received.

Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 drivers/virtio/virtio_balloon.c | 98 +++++++++++++++++++++++++++--------------
 1 file changed, 65 insertions(+), 33 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 728ecd1..45d32f5 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -61,6 +61,10 @@ enum virtio_balloon_vq {
 	VIRTIO_BALLOON_VQ_MAX
 };
 
+enum virtio_balloon_config_read {
+	VIRTIO_BALLOON_CONFIG_READ_CMD_ID = 0,
+};
+
 struct virtio_balloon {
 	struct virtio_device *vdev;
 	struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
@@ -77,14 +81,20 @@ struct virtio_balloon {
 	/* Prevent updating balloon when it is being canceled. */
 	spinlock_t stop_update_lock;
 	bool stop_update;
+	/* Bitmap to indicate if reading the related config fields are needed */
+	unsigned long config_read_bitmap;
 
 	/* The list of allocated free pages, waiting to be given back to mm */
 	struct list_head free_page_list;
 	spinlock_t free_page_list_lock;
 	/* The number of free page blocks on the above list */
 	unsigned long num_free_page_blocks;
-	/* The cmd id received from host */
-	u32 cmd_id_received;
+	/*
+	 * The cmd id received from host.
+	 * Read it via virtio_balloon_cmd_id_received to get the latest value
+	 * sent from host.
+	 */
+	u32 cmd_id_received_cache;
 	/* The cmd id that is actively in use */
 	__virtio32 cmd_id_active;
 	/* Buffer to store the stop sign */
@@ -390,37 +400,31 @@ static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb,
 	return num_returned;
 }
 
+static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb)
+{
+	if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
+		return;
+
+	/* No need to queue the work if the bit was already set. */
+	if (test_and_set_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			     &vb->config_read_bitmap))
+		return;
+
+	queue_work(vb->balloon_wq, &vb->report_free_page_work);
+}
+
 static void virtballoon_changed(struct virtio_device *vdev)
 {
 	struct virtio_balloon *vb = vdev->priv;
 	unsigned long flags;
-	s64 diff = towards_target(vb);
-
-	if (diff) {
-		spin_lock_irqsave(&vb->stop_update_lock, flags);
-		if (!vb->stop_update)
-			queue_work(system_freezable_wq,
-				   &vb->update_balloon_size_work);
-		spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-	}
 
-	if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
-		virtio_cread(vdev, struct virtio_balloon_config,
-			     free_page_report_cmd_id, &vb->cmd_id_received);
-		if (vb->cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
-			/* Pass ULONG_MAX to give back all the free pages */
-			return_free_pages_to_mm(vb, ULONG_MAX);
-		} else if (vb->cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
-			   vb->cmd_id_received !=
-			   virtio32_to_cpu(vdev, vb->cmd_id_active)) {
-			spin_lock_irqsave(&vb->stop_update_lock, flags);
-			if (!vb->stop_update) {
-				queue_work(vb->balloon_wq,
-					   &vb->report_free_page_work);
-			}
-			spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-		}
+	spin_lock_irqsave(&vb->stop_update_lock, flags);
+	if (!vb->stop_update) {
+		queue_work(system_freezable_wq,
+			   &vb->update_balloon_size_work);
+		virtio_balloon_queue_free_page_work(vb);
 	}
+	spin_unlock_irqrestore(&vb->stop_update_lock, flags);
 }
 
 static void update_balloon_size(struct virtio_balloon *vb)
@@ -527,6 +531,17 @@ static int init_vqs(struct virtio_balloon *vb)
 	return 0;
 }
 
+static u32 virtio_balloon_cmd_id_received(struct virtio_balloon *vb)
+{
+	if (test_and_clear_bit(VIRTIO_BALLOON_CONFIG_READ_CMD_ID,
+			       &vb->config_read_bitmap))
+		virtio_cread(vb->vdev, struct virtio_balloon_config,
+			     free_page_report_cmd_id,
+			     &vb->cmd_id_received_cache);
+
+	return vb->cmd_id_received_cache;
+}
+
 static int send_cmd_id_start(struct virtio_balloon *vb)
 {
 	struct scatterlist sg;
@@ -537,7 +552,8 @@ static int send_cmd_id_start(struct virtio_balloon *vb)
 	while (virtqueue_get_buf(vq, &unused))
 		;
 
-	vb->cmd_id_active = cpu_to_virtio32(vb->vdev, vb->cmd_id_received);
+	vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
+					virtio_balloon_cmd_id_received(vb));
 	sg_init_one(&sg, &vb->cmd_id_active, sizeof(vb->cmd_id_active));
 	err = virtqueue_add_outbuf(vq, &sg, 1, &vb->cmd_id_active, GFP_KERNEL);
 	if (!err)
@@ -620,7 +636,8 @@ static int send_free_pages(struct virtio_balloon *vb)
 		 * stop the reporting.
 		 */
 		cmd_id_active = virtio32_to_cpu(vb->vdev, vb->cmd_id_active);
-		if (cmd_id_active != vb->cmd_id_received)
+		if (unlikely(cmd_id_active !=
+			     virtio_balloon_cmd_id_received(vb)))
 			break;
 
 		/*
@@ -637,11 +654,9 @@ static int send_free_pages(struct virtio_balloon *vb)
 	return 0;
 }
 
-static void report_free_page_func(struct work_struct *work)
+static void virtio_balloon_report_free_page(struct virtio_balloon *vb)
 {
 	int err;
-	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
-						 report_free_page_work);
 	struct device *dev = &vb->vdev->dev;
 
 	/* Start by sending the received cmd id to host with an outbuf. */
@@ -659,6 +674,23 @@ static void report_free_page_func(struct work_struct *work)
 		dev_err(dev, "Failed to send a stop id, err = %d\n", err);
 }
 
+static void report_free_page_func(struct work_struct *work)
+{
+	struct virtio_balloon *vb = container_of(work, struct virtio_balloon,
+						 report_free_page_work);
+	u32 cmd_id_received;
+
+	cmd_id_received = virtio_balloon_cmd_id_received(vb);
+	if (cmd_id_received == VIRTIO_BALLOON_CMD_ID_DONE) {
+		/* Pass ULONG_MAX to give back all the free pages */
+		return_free_pages_to_mm(vb, ULONG_MAX);
+	} else if (cmd_id_received != VIRTIO_BALLOON_CMD_ID_STOP &&
+		   cmd_id_received !=
+		   virtio32_to_cpu(vb->vdev, vb->cmd_id_active)) {
+		virtio_balloon_report_free_page(vb);
+	}
+}
+
 #ifdef CONFIG_BALLOON_COMPACTION
 /*
  * virtballoon_migratepage - perform the balloon page migration on behalf of
@@ -885,7 +917,7 @@ static int virtballoon_probe(struct virtio_device *vdev)
 			goto out_del_vqs;
 		}
 		INIT_WORK(&vb->report_free_page_work, report_free_page_func);
-		vb->cmd_id_received = VIRTIO_BALLOON_CMD_ID_STOP;
+		vb->cmd_id_received_cache = VIRTIO_BALLOON_CMD_ID_STOP;
 		vb->cmd_id_active = cpu_to_virtio32(vb->vdev,
 						  VIRTIO_BALLOON_CMD_ID_STOP);
 		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
-- 
2.7.4


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^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [PATCH v4 2/3] virtio-balloon: improve update_balloon_size_func
  2019-01-08  4:50 ` [virtio-dev] " Wei Wang
@ 2019-01-08  4:50   ` Wei Wang
  -1 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

There is no need to update the balloon actual register when there is no
ballooning request. This patch avoids update_balloon_size when diff is 0.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 drivers/virtio/virtio_balloon.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 45d32f5..d48c12c 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
 			  update_balloon_size_work);
 	diff = towards_target(vb);
 
+	if (!diff)
+		return;
+
 	if (diff > 0)
 		diff -= fill_balloon(vb, diff);
-	else if (diff < 0)
+	else
 		diff += leak_balloon(vb, -diff);
 	update_balloon_size(vb);
 
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [PATCH v4 2/3] virtio-balloon: improve update_balloon_size_func
  2019-01-08  4:50 ` [virtio-dev] " Wei Wang
                   ` (2 preceding siblings ...)
  (?)
@ 2019-01-08  4:50 ` Wei Wang
  -1 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: pasic, dgilbert, pbonzini

There is no need to update the balloon actual register when there is no
ballooning request. This patch avoids update_balloon_size when diff is 0.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 drivers/virtio/virtio_balloon.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 45d32f5..d48c12c 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
 			  update_balloon_size_work);
 	diff = towards_target(vb);
 
+	if (!diff)
+		return;
+
 	if (diff > 0)
 		diff -= fill_balloon(vb, diff);
-	else if (diff < 0)
+	else
 		diff += leak_balloon(vb, -diff);
 	update_balloon_size(vb);
 
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [virtio-dev] [PATCH v4 2/3] virtio-balloon: improve update_balloon_size_func
@ 2019-01-08  4:50   ` Wei Wang
  0 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

There is no need to update the balloon actual register when there is no
ballooning request. This patch avoids update_balloon_size when diff is 0.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 drivers/virtio/virtio_balloon.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 45d32f5..d48c12c 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
 			  update_balloon_size_work);
 	diff = towards_target(vb);
 
+	if (!diff)
+		return;
+
 	if (diff > 0)
 		diff -= fill_balloon(vb, diff);
-	else if (diff < 0)
+	else
 		diff += leak_balloon(vb, -diff);
 	update_balloon_size(vb);
 
-- 
2.7.4


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^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [PATCH v4 3/3] virtio_balloon: remove the unnecessary 0-initialization
  2019-01-08  4:50 ` [virtio-dev] " Wei Wang
@ 2019-01-08  4:50   ` Wei Wang
  -1 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

We've changed to kzalloc the vb struct, so no need to 0-initialize
this field one more time.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
 drivers/virtio/virtio_balloon.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index d48c12c..048959a 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -925,7 +925,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
 						  VIRTIO_BALLOON_CMD_ID_STOP);
 		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
 						  VIRTIO_BALLOON_CMD_ID_STOP);
-		vb->num_free_page_blocks = 0;
 		spin_lock_init(&vb->free_page_list_lock);
 		INIT_LIST_HEAD(&vb->free_page_list);
 		if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [PATCH v4 3/3] virtio_balloon: remove the unnecessary 0-initialization
  2019-01-08  4:50 ` [virtio-dev] " Wei Wang
                   ` (4 preceding siblings ...)
  (?)
@ 2019-01-08  4:50 ` Wei Wang
  -1 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: pasic, dgilbert, pbonzini

We've changed to kzalloc the vb struct, so no need to 0-initialize
this field one more time.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
 drivers/virtio/virtio_balloon.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index d48c12c..048959a 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -925,7 +925,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
 						  VIRTIO_BALLOON_CMD_ID_STOP);
 		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
 						  VIRTIO_BALLOON_CMD_ID_STOP);
-		vb->num_free_page_blocks = 0;
 		spin_lock_init(&vb->free_page_list_lock);
 		INIT_LIST_HEAD(&vb->free_page_list);
 		if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 20+ messages in thread
* [virtio-dev] [PATCH v4 3/3] virtio_balloon: remove the unnecessary 0-initialization
@ 2019-01-08  4:50   ` Wei Wang
  0 siblings, 0 replies; 20+ messages in thread
From: Wei Wang @ 2019-01-08  4:50 UTC (permalink / raw)
  To: virtio-dev, linux-kernel, stable, virtualization, kvm, mst, cohuck
  Cc: borntraeger, pbonzini, dgilbert, wei.w.wang, pasic

We've changed to kzalloc the vb struct, so no need to 0-initialize
this field one more time.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
 drivers/virtio/virtio_balloon.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index d48c12c..048959a 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -925,7 +925,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
 						  VIRTIO_BALLOON_CMD_ID_STOP);
 		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
 						  VIRTIO_BALLOON_CMD_ID_STOP);
-		vb->num_free_page_blocks = 0;
 		spin_lock_init(&vb->free_page_list_lock);
 		INIT_LIST_HEAD(&vb->free_page_list);
 		if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
-- 
2.7.4


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^ permalink raw reply related	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 1/3] virtio-balloon: tweak config_changed implementation
  2019-01-08  4:50   ` [virtio-dev] " Wei Wang
@ 2019-01-08  7:10     ` Greg KH
  -1 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, linux-kernel, stable, virtualization, kvm, mst,
	cohuck, borntraeger, pbonzini, dgilbert, pasic

On Tue, Jan 08, 2019 at 12:50:03PM +0800, Wei Wang wrote:
> virtio-ccw has deadlock issues with reading the config space inside the
> interrupt context, so we tweak the virtballoon_changed implementation
> by moving the config read operations into the related workqueue contexts.
> The config_read_bitmap is used as a flag to the workqueue callbacks
> about the related config fields that need to be read.
> 
> The cmd_id_received is also renamed to cmd_id_received_cache, and
> the value should be obtained via virtio_balloon_cmd_id_received.
> 
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  drivers/virtio/virtio_balloon.c | 98 +++++++++++++++++++++++++++--------------
>  1 file changed, 65 insertions(+), 33 deletions(-)
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 1/3] virtio-balloon: tweak config_changed implementation
  2019-01-08  4:50   ` [virtio-dev] " Wei Wang
  (?)
  (?)
@ 2019-01-08  7:10   ` Greg KH
  -1 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, kvm, mst, cohuck, linux-kernel, stable,
	virtualization, pasic, pbonzini, dgilbert

On Tue, Jan 08, 2019 at 12:50:03PM +0800, Wei Wang wrote:
> virtio-ccw has deadlock issues with reading the config space inside the
> interrupt context, so we tweak the virtballoon_changed implementation
> by moving the config read operations into the related workqueue contexts.
> The config_read_bitmap is used as a flag to the workqueue callbacks
> about the related config fields that need to be read.
> 
> The cmd_id_received is also renamed to cmd_id_received_cache, and
> the value should be obtained via virtio_balloon_cmd_id_received.
> 
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  drivers/virtio/virtio_balloon.c | 98 +++++++++++++++++++++++++++--------------
>  1 file changed, 65 insertions(+), 33 deletions(-)
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 1/3] virtio-balloon: tweak config_changed implementation
@ 2019-01-08  7:10     ` Greg KH
  0 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, linux-kernel, stable, virtualization, kvm, mst,
	cohuck, borntraeger, pbonzini, dgilbert, pasic

On Tue, Jan 08, 2019 at 12:50:03PM +0800, Wei Wang wrote:
> virtio-ccw has deadlock issues with reading the config space inside the
> interrupt context, so we tweak the virtballoon_changed implementation
> by moving the config read operations into the related workqueue contexts.
> The config_read_bitmap is used as a flag to the workqueue callbacks
> about the related config fields that need to be read.
> 
> The cmd_id_received is also renamed to cmd_id_received_cache, and
> the value should be obtained via virtio_balloon_cmd_id_received.
> 
> Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
> Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  drivers/virtio/virtio_balloon.c | 98 +++++++++++++++++++++++++++--------------
>  1 file changed, 65 insertions(+), 33 deletions(-)
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 2/3] virtio-balloon: improve update_balloon_size_func
  2019-01-08  4:50   ` [virtio-dev] " Wei Wang
  (?)
@ 2019-01-08  7:10     ` Greg KH
  -1 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, linux-kernel, stable, virtualization, kvm, mst,
	cohuck, borntraeger, pbonzini, dgilbert, pasic

On Tue, Jan 08, 2019 at 12:50:04PM +0800, Wei Wang wrote:
> There is no need to update the balloon actual register when there is no
> ballooning request. This patch avoids update_balloon_size when diff is 0.
> 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  drivers/virtio/virtio_balloon.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 45d32f5..d48c12c 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
>  			  update_balloon_size_work);
>  	diff = towards_target(vb);
>  
> +	if (!diff)
> +		return;
> +
>  	if (diff > 0)
>  		diff -= fill_balloon(vb, diff);
> -	else if (diff < 0)
> +	else
>  		diff += leak_balloon(vb, -diff);
>  	update_balloon_size(vb);
>  
> -- 
> 2.7.4
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 2/3] virtio-balloon: improve update_balloon_size_func
@ 2019-01-08  7:10     ` Greg KH
  0 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, kvm, mst, cohuck, linux-kernel, stable,
	virtualization, pasic, pbonzini, dgilbert

On Tue, Jan 08, 2019 at 12:50:04PM +0800, Wei Wang wrote:
> There is no need to update the balloon actual register when there is no
> ballooning request. This patch avoids update_balloon_size when diff is 0.
> 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  drivers/virtio/virtio_balloon.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 45d32f5..d48c12c 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
>  			  update_balloon_size_work);
>  	diff = towards_target(vb);
>  
> +	if (!diff)
> +		return;
> +
>  	if (diff > 0)
>  		diff -= fill_balloon(vb, diff);
> -	else if (diff < 0)
> +	else
>  		diff += leak_balloon(vb, -diff);
>  	update_balloon_size(vb);
>  
> -- 
> 2.7.4
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 2/3] virtio-balloon: improve update_balloon_size_func
@ 2019-01-08  7:10     ` Greg KH
  0 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, linux-kernel, stable, virtualization, kvm, mst,
	cohuck, borntraeger, pbonzini, dgilbert, pasic

On Tue, Jan 08, 2019 at 12:50:04PM +0800, Wei Wang wrote:
> There is no need to update the balloon actual register when there is no
> ballooning request. This patch avoids update_balloon_size when diff is 0.
> 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  drivers/virtio/virtio_balloon.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 45d32f5..d48c12c 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -457,9 +457,12 @@ static void update_balloon_size_func(struct work_struct *work)
>  			  update_balloon_size_work);
>  	diff = towards_target(vb);
>  
> +	if (!diff)
> +		return;
> +
>  	if (diff > 0)
>  		diff -= fill_balloon(vb, diff);
> -	else if (diff < 0)
> +	else
>  		diff += leak_balloon(vb, -diff);
>  	update_balloon_size(vb);
>  
> -- 
> 2.7.4
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 3/3] virtio_balloon: remove the unnecessary 0-initialization
  2019-01-08  4:50   ` [virtio-dev] " Wei Wang
@ 2019-01-08  7:10     ` Greg KH
  -1 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, linux-kernel, stable, virtualization, kvm, mst,
	cohuck, borntraeger, pbonzini, dgilbert, pasic

On Tue, Jan 08, 2019 at 12:50:05PM +0800, Wei Wang wrote:
> We've changed to kzalloc the vb struct, so no need to 0-initialize
> this field one more time.
> 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> ---
>  drivers/virtio/virtio_balloon.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index d48c12c..048959a 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -925,7 +925,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
>  						  VIRTIO_BALLOON_CMD_ID_STOP);
>  		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
>  						  VIRTIO_BALLOON_CMD_ID_STOP);
> -		vb->num_free_page_blocks = 0;
>  		spin_lock_init(&vb->free_page_list_lock);
>  		INIT_LIST_HEAD(&vb->free_page_list);
>  		if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
> -- 
> 2.7.4
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 3/3] virtio_balloon: remove the unnecessary 0-initialization
  2019-01-08  4:50   ` [virtio-dev] " Wei Wang
  (?)
  (?)
@ 2019-01-08  7:10   ` Greg KH
  -1 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, kvm, mst, cohuck, linux-kernel, stable,
	virtualization, pasic, pbonzini, dgilbert

On Tue, Jan 08, 2019 at 12:50:05PM +0800, Wei Wang wrote:
> We've changed to kzalloc the vb struct, so no need to 0-initialize
> this field one more time.
> 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> ---
>  drivers/virtio/virtio_balloon.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index d48c12c..048959a 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -925,7 +925,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
>  						  VIRTIO_BALLOON_CMD_ID_STOP);
>  		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
>  						  VIRTIO_BALLOON_CMD_ID_STOP);
> -		vb->num_free_page_blocks = 0;
>  		spin_lock_init(&vb->free_page_list_lock);
>  		INIT_LIST_HEAD(&vb->free_page_list);
>  		if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
> -- 
> 2.7.4
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
* Re: [PATCH v4 3/3] virtio_balloon: remove the unnecessary 0-initialization
@ 2019-01-08  7:10     ` Greg KH
  0 siblings, 0 replies; 20+ messages in thread
From: Greg KH @ 2019-01-08  7:10 UTC (permalink / raw)
  To: Wei Wang
  Cc: virtio-dev, linux-kernel, stable, virtualization, kvm, mst,
	cohuck, borntraeger, pbonzini, dgilbert, pasic

On Tue, Jan 08, 2019 at 12:50:05PM +0800, Wei Wang wrote:
> We've changed to kzalloc the vb struct, so no need to 0-initialize
> this field one more time.
> 
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> ---
>  drivers/virtio/virtio_balloon.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index d48c12c..048959a 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -925,7 +925,6 @@ static int virtballoon_probe(struct virtio_device *vdev)
>  						  VIRTIO_BALLOON_CMD_ID_STOP);
>  		vb->cmd_id_stop = cpu_to_virtio32(vb->vdev,
>  						  VIRTIO_BALLOON_CMD_ID_STOP);
> -		vb->num_free_page_blocks = 0;
>  		spin_lock_init(&vb->free_page_list_lock);
>  		INIT_LIST_HEAD(&vb->free_page_list);
>  		if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
> -- 
> 2.7.4
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

^ permalink raw reply	[flat|nested] 20+ messages in thread
end of thread, other threads:[~2019-01-08  7:10 UTC | newest]

Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-01-08  4:50 [PATCH v4 0/3] virtio-balloon: tweak config_changed Wei Wang
2019-01-08  4:50 ` [virtio-dev] " Wei Wang
2019-01-08  4:50 ` [PATCH v4 1/3] virtio-balloon: tweak config_changed implementation Wei Wang
2019-01-08  4:50 ` Wei Wang
2019-01-08  4:50   ` [virtio-dev] " Wei Wang
2019-01-08  7:10   ` Greg KH
2019-01-08  7:10     ` Greg KH
2019-01-08  7:10   ` Greg KH
2019-01-08  4:50 ` [PATCH v4 2/3] virtio-balloon: improve update_balloon_size_func Wei Wang
2019-01-08  4:50 ` Wei Wang
2019-01-08  4:50   ` [virtio-dev] " Wei Wang
2019-01-08  7:10   ` Greg KH
2019-01-08  7:10     ` Greg KH
2019-01-08  7:10     ` Greg KH
2019-01-08  4:50 ` [PATCH v4 3/3] virtio_balloon: remove the unnecessary 0-initialization Wei Wang
2019-01-08  4:50 ` Wei Wang
2019-01-08  4:50   ` [virtio-dev] " Wei Wang
2019-01-08  7:10   ` Greg KH
2019-01-08  7:10     ` Greg KH
2019-01-08  7:10   ` Greg KH

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