From: "Michael S. Tsirkin" <mst@redhat.com>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: nitesh@redhat.com, kvm@vger.kernel.org, david@redhat.com,
dave.hansen@intel.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, akpm@linux-foundation.org,
yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com,
konrad.wilk@oracle.com, willy@infradead.org,
lcapitulino@redhat.com, wei.w.wang@intel.com,
aarcange@redhat.com, pbonzini@redhat.com,
dan.j.williams@intel.com, alexander.h.duyck@linux.intel.com
Subject: Re: [PATCH v4 6/6] virtio-balloon: Add support for providing unused page reports to host
Date: Mon, 12 Aug 2019 05:53:12 -0400 [thread overview]
Message-ID: <20190812055054-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20190807224219.6891.25387.stgit@localhost.localdomain>
On Wed, Aug 07, 2019 at 03:42:19PM -0700, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
>
> Add support for the page reporting feature provided by virtio-balloon.
> Reporting differs from the regular balloon functionality in that is is
> much less durable than a standard memory balloon. Instead of creating a
> list of pages that cannot be accessed the pages are only inaccessible
> while they are being indicated to the virtio interface. Once the
> interface has acknowledged them they are placed back into their respective
> free lists and are once again accessible by the guest system.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> ---
> drivers/virtio/Kconfig | 1 +
> drivers/virtio/virtio_balloon.c | 65 +++++++++++++++++++++++++++++++++++
> include/uapi/linux/virtio_balloon.h | 1 +
> 3 files changed, 67 insertions(+)
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index 078615cf2afc..4b2dd8259ff5 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -58,6 +58,7 @@ config VIRTIO_BALLOON
> tristate "Virtio balloon driver"
> depends on VIRTIO
> select MEMORY_BALLOON
> + select PAGE_REPORTING
> ---help---
> This driver supports increasing and decreasing the amount
> of memory within a KVM guest.
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 2c19457ab573..52f9eeda1877 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -19,6 +19,7 @@
> #include <linux/mount.h>
> #include <linux/magic.h>
> #include <linux/pseudo_fs.h>
> +#include <linux/page_reporting.h>
>
> /*
> * Balloon device works in 4K page units. So each page is pointed to by
> @@ -37,6 +38,9 @@
> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \
> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT))
>
> +/* limit on the number of pages that can be on the reporting vq */
> +#define VIRTIO_BALLOON_VRING_HINTS_MAX 16
> +
> #ifdef CONFIG_BALLOON_COMPACTION
> static struct vfsmount *balloon_mnt;
> #endif
> @@ -46,6 +50,7 @@ enum virtio_balloon_vq {
> VIRTIO_BALLOON_VQ_DEFLATE,
> VIRTIO_BALLOON_VQ_STATS,
> VIRTIO_BALLOON_VQ_FREE_PAGE,
> + VIRTIO_BALLOON_VQ_REPORTING,
> VIRTIO_BALLOON_VQ_MAX
> };
>
> @@ -113,6 +118,10 @@ struct virtio_balloon {
>
> /* To register a shrinker to shrink memory upon memory pressure */
> struct shrinker shrinker;
> +
> + /* Unused page reporting device */
> + struct virtqueue *reporting_vq;
> + struct page_reporting_dev_info ph_dev_info;
> };
>
> static struct virtio_device_id id_table[] = {
> @@ -152,6 +161,32 @@ static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
>
> }
>
> +void virtballoon_unused_page_report(struct page_reporting_dev_info *ph_dev_info,
> + unsigned int nents)
> +{
> + struct virtio_balloon *vb =
> + container_of(ph_dev_info, struct virtio_balloon, ph_dev_info);
> + struct virtqueue *vq = vb->reporting_vq;
> + unsigned int unused, err;
> +
> + /* We should always be able to add these buffers to an empty queue. */
> + err = virtqueue_add_inbuf(vq, ph_dev_info->sg, nents, vb,
> + GFP_NOWAIT | __GFP_NOWARN);
> +
> + /*
> + * In the extremely unlikely case that something has changed and we
> + * are able to trigger an error we will simply display a warning
> + * and exit without actually processing the pages.
> + */
> + if (WARN_ON(err))
> + return;
> +
> + virtqueue_kick(vq);
> +
> + /* When host has read buffer, this completes via balloon_ack */
> + wait_event(vb->acked, virtqueue_get_buf(vq, &unused));
> +}
> +
> static void set_page_pfns(struct virtio_balloon *vb,
> __virtio32 pfns[], struct page *page)
> {
> @@ -476,6 +511,7 @@ static int init_vqs(struct virtio_balloon *vb)
> names[VIRTIO_BALLOON_VQ_DEFLATE] = "deflate";
> names[VIRTIO_BALLOON_VQ_STATS] = NULL;
> names[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
> + names[VIRTIO_BALLOON_VQ_REPORTING] = NULL;
>
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
> names[VIRTIO_BALLOON_VQ_STATS] = "stats";
> @@ -487,11 +523,19 @@ static int init_vqs(struct virtio_balloon *vb)
> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL;
> }
>
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
> + names[VIRTIO_BALLOON_VQ_REPORTING] = "reporting_vq";
> + callbacks[VIRTIO_BALLOON_VQ_REPORTING] = balloon_ack;
> + }
> +
> err = vb->vdev->config->find_vqs(vb->vdev, VIRTIO_BALLOON_VQ_MAX,
> vqs, callbacks, names, NULL, NULL);
> if (err)
> return err;
>
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
> + vb->reporting_vq = vqs[VIRTIO_BALLOON_VQ_REPORTING];
> +
> vb->inflate_vq = vqs[VIRTIO_BALLOON_VQ_INFLATE];
> vb->deflate_vq = vqs[VIRTIO_BALLOON_VQ_DEFLATE];
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
> @@ -931,12 +975,30 @@ static int virtballoon_probe(struct virtio_device *vdev)
> if (err)
> goto out_del_balloon_wq;
> }
> +
> + vb->ph_dev_info.report = virtballoon_unused_page_report;
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) {
> + unsigned int capacity;
> +
> + capacity = min_t(unsigned int,
> + virtqueue_get_vring_size(vb->reporting_vq) - 1,
> + VIRTIO_BALLOON_VRING_HINTS_MAX);
> + vb->ph_dev_info.capacity = capacity;
> +
> + err = page_reporting_startup(&vb->ph_dev_info);
> + if (err)
> + goto out_unregister_shrinker;
> + }
> +
> virtio_device_ready(vdev);
>
> if (towards_target(vb))
> virtballoon_changed(vdev);
> return 0;
>
> +out_unregister_shrinker:
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
> + virtio_balloon_unregister_shrinker(vb);
> out_del_balloon_wq:
> if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT))
> destroy_workqueue(vb->balloon_wq);
> @@ -965,6 +1027,8 @@ static void virtballoon_remove(struct virtio_device *vdev)
> {
> struct virtio_balloon *vb = vdev->priv;
>
> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING))
> + page_reporting_shutdown(&vb->ph_dev_info);
> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
> virtio_balloon_unregister_shrinker(vb);
> spin_lock_irq(&vb->stop_update_lock);
> @@ -1034,6 +1098,7 @@ static int virtballoon_validate(struct virtio_device *vdev)
> VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
> VIRTIO_BALLOON_F_FREE_PAGE_HINT,
> VIRTIO_BALLOON_F_PAGE_POISON,
> + VIRTIO_BALLOON_F_REPORTING,
> };
>
> static struct virtio_driver virtio_balloon_driver = {
> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
> index a1966cd7b677..19974392d324 100644
> --- a/include/uapi/linux/virtio_balloon.h
> +++ b/include/uapi/linux/virtio_balloon.h
> @@ -36,6 +36,7 @@
> #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
> #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */
> #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */
> +#define VIRTIO_BALLOON_F_REPORTING 5 /* Page reporting virtqueue */
>
> /* Size of a PFN in the balloon interface. */
> #define VIRTIO_BALLOON_PFN_SHIFT 12
Just a small comment: same as any feature bit,
or indeed any host/guest interface changes, please
CC virtio-dev on any changes to this UAPI file.
We must maintain these in the central place in the spec,
otherwise we run a risk of conflicts.
--
MST
next prev parent reply other threads:[~2019-08-12 9:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 22:41 [PATCH v4 0/6] mm / virtio: Provide support for unused page reporting Alexander Duyck
2019-08-07 22:41 ` [PATCH v4 1/6] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-08-07 22:41 ` [PATCH v4 2/6] mm: Move set/get_pcppage_migratetype to mmzone.h Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 3/6] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 4/6] mm: Introduce Reported pages Alexander Duyck
2019-08-08 13:45 ` Nitesh Narayan Lal
2019-08-08 15:11 ` Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 5/6] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2019-08-07 22:42 ` [PATCH v4 6/6] virtio-balloon: Add support for providing unused page reports to host Alexander Duyck
2019-08-12 9:53 ` Michael S. Tsirkin [this message]
2019-08-12 15:20 ` Alexander Duyck
2019-08-12 15:43 ` Michael S. Tsirkin
2019-08-12 15:49 ` David Hildenbrand
2019-08-12 16:09 ` Alexander Duyck
2019-08-07 22:43 ` [PATCH v4 QEMU 1/3] virtio-ballon: Implement support for page poison tracking feature Alexander Duyck
2019-08-07 22:43 ` [PATCH v4 QEMU 2/3] virtio-balloon: Add bit to notify guest of unused page reporting Alexander Duyck
2019-08-07 22:43 ` [PATCH v4 QEMU 3/3] virtio-balloon: Provide a interface for " Alexander Duyck
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