[PATCH v29 4/4] virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON

[Wei Wang]

The VIRTIO_BALLOON_F_PAGE_POISON feature bit is used to indicate if the
guest is using page poisoning. Guest writes to the poison_val config
field to tell host about the page poisoning value in use.

Signed-off-by: Wei Wang 
Suggested-by: Michael S. Tsirkin 
Cc: Michael S. Tsirkin 
Cc: Michal Hocko 
Cc: Andrew Morton 
---
 drivers/virtio/virtio_balloon.c | 10 ++
 include/uapi/linux/virtio_balloon.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 18d24a4..6de9339 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -699,6 +699,7 @@ static struct file_system_type balloon_fs = {
 static int virtballoon_probe(struct virtio_device *vdev)
 {
struct virtio_balloon *vb;
+   __u32 poison_val;
int err;
 
if (!vdev->config->get) {
@@ -744,6 +745,11 @@ static int virtballoon_probe(struct virtio_device *vdev)
vb->stop_cmd_id = cpu_to_virtio32(vb->vdev,
VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID);
INIT_WORK(>report_free_page_work, report_free_page_func);
+   if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
+   memset(_val, PAGE_POISON, sizeof(poison_val));
+   virtio_cwrite(vb->vdev, struct virtio_balloon_config,
+ poison_val, _val);
+   }
}
 
vb->nb.notifier_call = virtballoon_oom_notify;
@@ -862,6 +868,9 @@ static int virtballoon_restore(struct virtio_device *vdev)
 
 static int virtballoon_validate(struct virtio_device *vdev)
 {
+   if (!page_poisoning_enabled())
+   __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
+
__virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
return 0;
 }
@@ -871,6 +880,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
VIRTIO_BALLOON_F_FREE_PAGE_HINT,
+   VIRTIO_BALLOON_F_PAGE_POISON,
 };
 
 static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h 
b/include/uapi/linux/virtio_balloon.h
index b2d86c2..8b93581 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -35,6 +35,7 @@
 #define VIRTIO_BALLOON_F_STATS_VQ  1 /* Memory Stats virtqueue */
 #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM2 /* Deflate balloon on OOM */
 #define VIRTIO_BALLOON_F_FREE_PAGE_HINT3 /* VQ to report free pages */
+#define VIRTIO_BALLOON_F_PAGE_POISON   4 /* Guest is using page poisoning */
 
 /* Size of a PFN in the balloon interface. */
 #define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -47,6 +48,8 @@ struct virtio_balloon_config {
__u32 actual;
/* Free page report command id, readonly by guest */
__u32 free_page_report_cmd_id;
+   /* Stores PAGE_POISON if page poisoning is in use */
+   __u32 poison_val;
 };
 
 #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
-- 
2.7.4

[PATCH v29 4/4] virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON

[Wei Wang]

The VIRTIO_BALLOON_F_PAGE_POISON feature bit is used to indicate if the
guest is using page poisoning. Guest writes to the poison_val config
field to tell host about the page poisoning value in use.

Signed-off-by: Wei Wang 
Suggested-by: Michael S. Tsirkin 
Cc: Michael S. Tsirkin 
Cc: Michal Hocko 
Cc: Andrew Morton 
---
 drivers/virtio/virtio_balloon.c | 10 ++
 include/uapi/linux/virtio_balloon.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 18d24a4..6de9339 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -699,6 +699,7 @@ static struct file_system_type balloon_fs = {
 static int virtballoon_probe(struct virtio_device *vdev)
 {
struct virtio_balloon *vb;
+   __u32 poison_val;
int err;
 
if (!vdev->config->get) {
@@ -744,6 +745,11 @@ static int virtballoon_probe(struct virtio_device *vdev)
vb->stop_cmd_id = cpu_to_virtio32(vb->vdev,
VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID);
INIT_WORK(>report_free_page_work, report_free_page_func);
+   if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
+   memset(_val, PAGE_POISON, sizeof(poison_val));
+   virtio_cwrite(vb->vdev, struct virtio_balloon_config,
+ poison_val, _val);
+   }
}
 
vb->nb.notifier_call = virtballoon_oom_notify;
@@ -862,6 +868,9 @@ static int virtballoon_restore(struct virtio_device *vdev)
 
 static int virtballoon_validate(struct virtio_device *vdev)
 {
+   if (!page_poisoning_enabled())
+   __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
+
__virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
return 0;
 }
@@ -871,6 +880,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
VIRTIO_BALLOON_F_FREE_PAGE_HINT,
+   VIRTIO_BALLOON_F_PAGE_POISON,
 };
 
 static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h 
b/include/uapi/linux/virtio_balloon.h
index b2d86c2..8b93581 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -35,6 +35,7 @@
 #define VIRTIO_BALLOON_F_STATS_VQ  1 /* Memory Stats virtqueue */
 #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM2 /* Deflate balloon on OOM */
 #define VIRTIO_BALLOON_F_FREE_PAGE_HINT3 /* VQ to report free pages */
+#define VIRTIO_BALLOON_F_PAGE_POISON   4 /* Guest is using page poisoning */
 
 /* Size of a PFN in the balloon interface. */
 #define VIRTIO_BALLOON_PFN_SHIFT 12
@@ -47,6 +48,8 @@ struct virtio_balloon_config {
__u32 actual;
/* Free page report command id, readonly by guest */
__u32 free_page_report_cmd_id;
+   /* Stores PAGE_POISON if page poisoning is in use */
+   __u32 poison_val;
 };
 
 #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
-- 
2.7.4