2019-09-09 02:32:56

by Alexander Duyck

Subject: [PATCH v9 7/8] virtio-balloon: Pull page poisoning config out of free page hinting

From: Alexander Duyck <[email protected]>

Currently the page poisoning setting wasn't being enabled unless free page
hinting was enabled. However we will need the page poisoning tracking logic
as well for unused page reporting. As such pull it out and make it a
separate bit of config in the probe function.

In addition we can actually wrap the code in a check for NO_SANITY. If we
don't care what is actually in the page we can just default to 0 and leave
it there.

Signed-off-by: Alexander Duyck <[email protected]>
---
drivers/virtio/virtio_balloon.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 226fbb995fb0..d2547df7de93 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -842,7 +842,6 @@ static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
- __u32 poison_val;
int err;

if (!vdev->config->get) {
@@ -909,11 +908,18 @@ static int virtballoon_probe(struct virtio_device *vdev)
VIRTIO_BALLOON_CMD_ID_STOP);
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)) {
- memset(&poison_val, PAGE_POISON, sizeof(poison_val));
- virtio_cwrite(vb->vdev, struct virtio_balloon_config,
- poison_val, &poison_val);
- }
+ }
+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
+ __u32 poison_val;
+
+ /*
+ * Let hypervisor know that we are expecting a specific
+ * value to be written back in unused pages.
+ */
+ memset(&poison_val, PAGE_POISON, sizeof(poison_val));
+
+ virtio_cwrite(vb->vdev, struct virtio_balloon_config,
+ poison_val, &poison_val);
}
/*
* We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a
@@ -1014,7 +1020,9 @@ static int virtballoon_restore(struct virtio_device *vdev)

static int virtballoon_validate(struct virtio_device *vdev)
{
- if (!page_poisoning_enabled())
+ /* Notify host if we care about poison value */
+ if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) ||
+ !page_poisoning_enabled())
__virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);

__virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);

2019-09-10 02:36:26

by David Hildenbrand

Subject: Re: [PATCH v9 7/8] virtio-balloon: Pull page poisoning config out of free page hinting

On 07.09.19 19:26, Alexander Duyck wrote:
> From: Alexander Duyck <[email protected]>
>
> Currently the page poisoning setting wasn't being enabled unless free page
> hinting was enabled. However we will need the page poisoning tracking logic
> as well for unused page reporting. As such pull it out and make it a
> separate bit of config in the probe function.
>
> In addition we can actually wrap the code in a check for NO_SANITY. If we
> don't care what is actually in the page we can just default to 0 and leave
> it there.
>
> Signed-off-by: Alexander Duyck <[email protected]>
> ---
> drivers/virtio/virtio_balloon.c | 22 +++++++++++++++-------
> 1 file changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 226fbb995fb0..d2547df7de93 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -842,7 +842,6 @@ static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
> static int virtballoon_probe(struct virtio_device *vdev)
> {
> struct virtio_balloon *vb;
> - __u32 poison_val;
> int err;
>
> if (!vdev->config->get) {
> @@ -909,11 +908,18 @@ static int virtballoon_probe(struct virtio_device *vdev)
> VIRTIO_BALLOON_CMD_ID_STOP);
> 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)) {
> - memset(&poison_val, PAGE_POISON, sizeof(poison_val));
> - virtio_cwrite(vb->vdev, struct virtio_balloon_config,
> - poison_val, &poison_val);
> - }
> + }
> + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
> + __u32 poison_val;
> +
> + /*
> + * Let hypervisor know that we are expecting a specific
> + * value to be written back in unused pages.
> + */

"Let the hypervisor know" ... ?

> + memset(&poison_val, PAGE_POISON, sizeof(poison_val));
> +
> + virtio_cwrite(vb->vdev, struct virtio_balloon_config,
> + poison_val, &poison_val);
> }
> /*
> * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a
> @@ -1014,7 +1020,9 @@ static int virtballoon_restore(struct virtio_device *vdev)
>
> static int virtballoon_validate(struct virtio_device *vdev)
> {
> - if (!page_poisoning_enabled())
> + /* Notify host if we care about poison value */

"Tell the host whether we care about poisoned pages." ?

> + if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) ||
> + !page_poisoning_enabled())
> __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
>
> __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
>

Reviewed-by: David Hildenbrand <[email protected]>

--

Thanks,

David / dhildenb

2019-09-10 18:32:21

by Alexander Duyck

Subject: Re: [PATCH v9 7/8] virtio-balloon: Pull page poisoning config out of free page hinting

On Mon, 2019-09-09 at 10:59 +0200, David Hildenbrand wrote:
> On 07.09.19 19:26, Alexander Duyck wrote:
> > From: Alexander Duyck <[email protected]>
> >
> > Currently the page poisoning setting wasn't being enabled unless free page
> > hinting was enabled. However we will need the page poisoning tracking logic
> > as well for unused page reporting. As such pull it out and make it a
> > separate bit of config in the probe function.
> >
> > In addition we can actually wrap the code in a check for NO_SANITY. If we
> > don't care what is actually in the page we can just default to 0 and leave
> > it there.
> >
> > Signed-off-by: Alexander Duyck <[email protected]>
> > ---
> > drivers/virtio/virtio_balloon.c | 22 +++++++++++++++-------
> > 1 file changed, 15 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> > index 226fbb995fb0..d2547df7de93 100644
> > --- a/drivers/virtio/virtio_balloon.c
> > +++ b/drivers/virtio/virtio_balloon.c
> > @@ -842,7 +842,6 @@ static int virtio_balloon_register_shrinker(struct virtio_balloon *vb)
> > static int virtballoon_probe(struct virtio_device *vdev)
> > {
> > struct virtio_balloon *vb;
> > - __u32 poison_val;
> > int err;
> >
> > if (!vdev->config->get) {
> > @@ -909,11 +908,18 @@ static int virtballoon_probe(struct virtio_device *vdev)
> > VIRTIO_BALLOON_CMD_ID_STOP);
> > 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)) {
> > - memset(&poison_val, PAGE_POISON, sizeof(poison_val));
> > - virtio_cwrite(vb->vdev, struct virtio_balloon_config,
> > - poison_val, &poison_val);
> > - }
> > + }
> > + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) {
> > + __u32 poison_val;
> > +
> > + /*
> > + * Let hypervisor know that we are expecting a specific
> > + * value to be written back in unused pages.
> > + */
>
> "Let the hypervisor know" ... ?
>
> > + memset(&poison_val, PAGE_POISON, sizeof(poison_val));
> > +
> > + virtio_cwrite(vb->vdev, struct virtio_balloon_config,
> > + poison_val, &poison_val);
> > }
> > /*
> > * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a
> > @@ -1014,7 +1020,9 @@ static int virtballoon_restore(struct virtio_device *vdev)
> >
> > static int virtballoon_validate(struct virtio_device *vdev)
> > {
> > - if (!page_poisoning_enabled())
> > + /* Notify host if we care about poison value */
>
> "Tell the host whether we care about poisoned pages." ?
>
> > + if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) ||
> > + !page_poisoning_enabled())
> > __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON);
> >
> > __virtio_clear_bit(vdev, VIRTIO_F_IOMMU_PLATFORM);
> >
>
> Reviewed-by: David Hildenbrand <[email protected]>
>

Thanks. I will update the comments for v10.

- Alex