| Message ID | 20190710195158.19640-3-nitesh@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: Support for page hinting | expand |
On Wed, Jul 10, 2019 at 03:51:58PM -0400, Nitesh Narayan Lal wrote: > Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the > host. If it is available and page_hinting_flag is set to true, page_hinting > is enabled and its callbacks are configured along with the max_pages count > which indicates the maximum number of pages that can be isolated and hinted > at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are > reported. To prevent any false OOM max_pages count is set to 16. > > By default page_hinting feature is enabled and gets loaded as soon > as the virtio-balloon driver is loaded. However, it could be disabled > by writing the page_hinting_flag which is a virtio-balloon parameter. > > Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> > --- > drivers/virtio/Kconfig | 1 + > drivers/virtio/virtio_balloon.c | 91 ++++++++++++++++++++++++++++- > include/uapi/linux/virtio_balloon.h | 11 ++++ > 3 files changed, 102 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > index 023fc3bc01c6..dcc0cb4269a5 100644 > --- a/drivers/virtio/Kconfig > +++ b/drivers/virtio/Kconfig > @@ -47,6 +47,7 @@ config VIRTIO_BALLOON > tristate "Virtio balloon driver" > depends on VIRTIO > select MEMORY_BALLOON > + select PAGE_HINTING > ---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 44339fc87cc7..1fb0eb0b2c20 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -18,6 +18,7 @@ > #include <linux/mm.h> > #include <linux/mount.h> > #include <linux/magic.h> > +#include <linux/page_hinting.h> > > /* > * Balloon device works in 4K page units. So each page is pointed to by > @@ -35,6 +36,12 @@ > /* The size of a free page block in bytes */ > #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ > (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) > +/* Number of isolated pages to be reported to the host at a time. > + * TODO: > + * 1. Set it via host. > + * 2. Find an optimal value for this. > + */ > +#define PAGE_HINTING_MAX_PAGES 16 > > #ifdef CONFIG_BALLOON_COMPACTION > static struct vfsmount *balloon_mnt; > @@ -45,6 +52,7 @@ enum virtio_balloon_vq { > VIRTIO_BALLOON_VQ_DEFLATE, > VIRTIO_BALLOON_VQ_STATS, > VIRTIO_BALLOON_VQ_FREE_PAGE, > + VIRTIO_BALLOON_VQ_HINTING, > VIRTIO_BALLOON_VQ_MAX > }; > > @@ -54,7 +62,8 @@ enum virtio_balloon_config_read { > > struct virtio_balloon { > struct virtio_device *vdev; > - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; > + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, > + *hinting_vq; > > /* Balloon's own wq for cpu-intensive work items */ > struct workqueue_struct *balloon_wq; > @@ -112,6 +121,9 @@ struct virtio_balloon { > > /* To register a shrinker to shrink memory upon memory pressure */ > struct shrinker shrinker; > + > + /* Array object pointing at the isolated pages ready for hinting */ > + struct isolated_memory isolated_pages[PAGE_HINTING_MAX_PAGES]; > }; > > static struct virtio_device_id id_table[] = { > @@ -119,6 +131,66 @@ static struct virtio_device_id id_table[] = { > { 0 }, > }; > > +static struct page_hinting_config page_hinting_conf; > +bool page_hinting_flag = true; > +struct virtio_balloon *hvb; > +module_param(page_hinting_flag, bool, 0444); > +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); > + > +static int page_hinting_report(void) > +{ > + struct virtqueue *vq = hvb->hinting_vq; > + struct scatterlist sg; > + int err = 0, unused; > + > + mutex_lock(&hvb->balloon_lock); > + sg_init_one(&sg, hvb->isolated_pages, sizeof(hvb->isolated_pages[0]) * > + PAGE_HINTING_MAX_PAGES); > + err = virtqueue_add_outbuf(vq, &sg, 1, hvb, GFP_KERNEL); In Alex's patch, I really like it that he's passing pages as sg entries. IMHO that's both cleaner and allows seamless support for arbitrary page sizes. In particular .... > + if (!err) > + virtqueue_kick(hvb->hinting_vq); > + wait_event(hvb->acked, virtqueue_get_buf(vq, &unused)); > + mutex_unlock(&hvb->balloon_lock); > + return err; > +} > + > +void hint_pages(struct list_head *pages) > +{ > + struct device *dev = &hvb->vdev->dev; > + struct page *page, *next; > + int idx = 0, order, err; > + unsigned long pfn; > + > + list_for_each_entry_safe(page, next, pages, lru) { > + pfn = page_to_pfn(page); > + order = page_private(page); > + hvb->isolated_pages[idx].phys_addr = pfn << PAGE_SHIFT; > + hvb->isolated_pages[idx].size = (1 << order) * PAGE_SIZE; > + idx++; ... passing native endian-ness values to host creates pain for cross-endian configurations. > + } > + err = page_hinting_report(); > + if (err < 0) > + dev_err(dev, "Failed to hint pages, err = %d\n", err); > +} > + > +static void page_hinting_init(struct virtio_balloon *vb) > +{ > + struct device *dev = &vb->vdev->dev; > + int err; > + > + page_hinting_conf.hint_pages = hint_pages; > + page_hinting_conf.max_pages = PAGE_HINTING_MAX_PAGES; > + err = page_hinting_enable(&page_hinting_conf); > + if (err < 0) { > + dev_err(dev, "Failed to enable page-hinting, err = %d\n", err); It would be nicer to disable the feature bit then, or fail probe completely. > + page_hinting_flag = false; > + page_hinting_conf.hint_pages = NULL; > + page_hinting_conf.max_pages = 0; > + return; > + } > + hvb = vb; > +} > + > static u32 page_to_balloon_pfn(struct page *page) > { > unsigned long pfn = page_to_pfn(page); > @@ -475,6 +547,7 @@ 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_HINTING] = NULL; > > if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { > names[VIRTIO_BALLOON_VQ_STATS] = "stats"; > @@ -486,11 +559,18 @@ static int init_vqs(struct virtio_balloon *vb) > callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; > } > > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { > + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; > + callbacks[VIRTIO_BALLOON_VQ_HINTING] = 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_HINTING)) > + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; > + > 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)) { > @@ -929,6 +1009,9 @@ static int virtballoon_probe(struct virtio_device *vdev) > if (err) > goto out_del_balloon_wq; > } > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && > + page_hinting_flag) > + page_hinting_init(vb); > virtio_device_ready(vdev); > > if (towards_target(vb)) > @@ -976,6 +1059,10 @@ static void virtballoon_remove(struct virtio_device *vdev) > destroy_workqueue(vb->balloon_wq); > } > > + if (!page_hinting_flag) { > + hvb = NULL; > + page_hinting_disable(); > + } > remove_common(vb); > #ifdef CONFIG_BALLOON_COMPACTION > if (vb->vb_dev_info.inode) > @@ -1030,8 +1117,10 @@ static unsigned int features[] = { > VIRTIO_BALLOON_F_MUST_TELL_HOST, > VIRTIO_BALLOON_F_STATS_VQ, > VIRTIO_BALLOON_F_DEFLATE_ON_OOM, > + VIRTIO_BALLOON_F_HINTING, > VIRTIO_BALLOON_F_FREE_PAGE_HINT, > VIRTIO_BALLOON_F_PAGE_POISON, > + VIRTIO_BALLOON_F_HINTING, > }; > > 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..29eed0ec83d3 100644 > --- a/include/uapi/linux/virtio_balloon.h > +++ b/include/uapi/linux/virtio_balloon.h > @@ -36,6 +36,8 @@ > #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 */ > +/* TODO: Find a better name to avoid any confusion with FREE_PAGE_HINT */ > +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ > > /* Size of a PFN in the balloon interface. */ > #define VIRTIO_BALLOON_PFN_SHIFT 12 > @@ -108,4 +110,13 @@ struct virtio_balloon_stat { > __virtio64 val; > } __attribute__((packed)); > > +/* > + * struct isolated_memory- holds the pages which will be reported to the host. > + * @phys_add: physical address associated with a page. > + * @size: total size of memory to be reported. > + */ > +struct isolated_memory { > + __virtio64 phys_addr; > + __virtio64 size; > +}; > #endif /* _LINUX_VIRTIO_BALLOON_H */ > -- > 2.21.0
On 24.07.19 21:47, Michael S. Tsirkin wrote: > On Wed, Jul 10, 2019 at 03:51:58PM -0400, Nitesh Narayan Lal wrote: >> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >> host. If it is available and page_hinting_flag is set to true, page_hinting >> is enabled and its callbacks are configured along with the max_pages count >> which indicates the maximum number of pages that can be isolated and hinted >> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >> reported. To prevent any false OOM max_pages count is set to 16. >> >> By default page_hinting feature is enabled and gets loaded as soon >> as the virtio-balloon driver is loaded. However, it could be disabled >> by writing the page_hinting_flag which is a virtio-balloon parameter. >> >> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> >> --- >> drivers/virtio/Kconfig | 1 + >> drivers/virtio/virtio_balloon.c | 91 ++++++++++++++++++++++++++++- >> include/uapi/linux/virtio_balloon.h | 11 ++++ >> 3 files changed, 102 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig >> index 023fc3bc01c6..dcc0cb4269a5 100644 >> --- a/drivers/virtio/Kconfig >> +++ b/drivers/virtio/Kconfig >> @@ -47,6 +47,7 @@ config VIRTIO_BALLOON >> tristate "Virtio balloon driver" >> depends on VIRTIO >> select MEMORY_BALLOON >> + select PAGE_HINTING >> ---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 44339fc87cc7..1fb0eb0b2c20 100644 >> --- a/drivers/virtio/virtio_balloon.c >> +++ b/drivers/virtio/virtio_balloon.c >> @@ -18,6 +18,7 @@ >> #include <linux/mm.h> >> #include <linux/mount.h> >> #include <linux/magic.h> >> +#include <linux/page_hinting.h> >> >> /* >> * Balloon device works in 4K page units. So each page is pointed to by >> @@ -35,6 +36,12 @@ >> /* The size of a free page block in bytes */ >> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >> +/* Number of isolated pages to be reported to the host at a time. >> + * TODO: >> + * 1. Set it via host. >> + * 2. Find an optimal value for this. >> + */ >> +#define PAGE_HINTING_MAX_PAGES 16 >> >> #ifdef CONFIG_BALLOON_COMPACTION >> static struct vfsmount *balloon_mnt; >> @@ -45,6 +52,7 @@ enum virtio_balloon_vq { >> VIRTIO_BALLOON_VQ_DEFLATE, >> VIRTIO_BALLOON_VQ_STATS, >> VIRTIO_BALLOON_VQ_FREE_PAGE, >> + VIRTIO_BALLOON_VQ_HINTING, >> VIRTIO_BALLOON_VQ_MAX >> }; >> >> @@ -54,7 +62,8 @@ enum virtio_balloon_config_read { >> >> struct virtio_balloon { >> struct virtio_device *vdev; >> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; >> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, >> + *hinting_vq; >> >> /* Balloon's own wq for cpu-intensive work items */ >> struct workqueue_struct *balloon_wq; >> @@ -112,6 +121,9 @@ struct virtio_balloon { >> >> /* To register a shrinker to shrink memory upon memory pressure */ >> struct shrinker shrinker; >> + >> + /* Array object pointing at the isolated pages ready for hinting */ >> + struct isolated_memory isolated_pages[PAGE_HINTING_MAX_PAGES]; >> }; >> >> static struct virtio_device_id id_table[] = { >> @@ -119,6 +131,66 @@ static struct virtio_device_id id_table[] = { >> { 0 }, >> }; >> >> +static struct page_hinting_config page_hinting_conf; >> +bool page_hinting_flag = true; >> +struct virtio_balloon *hvb; >> +module_param(page_hinting_flag, bool, 0444); >> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >> + >> +static int page_hinting_report(void) >> +{ >> + struct virtqueue *vq = hvb->hinting_vq; >> + struct scatterlist sg; >> + int err = 0, unused; >> + >> + mutex_lock(&hvb->balloon_lock); >> + sg_init_one(&sg, hvb->isolated_pages, sizeof(hvb->isolated_pages[0]) * >> + PAGE_HINTING_MAX_PAGES); >> + err = virtqueue_add_outbuf(vq, &sg, 1, hvb, GFP_KERNEL); > > In Alex's patch, I really like it that he's passing pages as sg > entries. IMHO that's both cleaner and allows seamless > support for arbitrary page sizes. > +1 I especially like passing full addresses and sizes instead of PFNs and orders (compared to Alex's v1, where he would pass PFNs and orders).
On 7/24/19 3:47 PM, Michael S. Tsirkin wrote: > On Wed, Jul 10, 2019 at 03:51:58PM -0400, Nitesh Narayan Lal wrote: >> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >> host. If it is available and page_hinting_flag is set to true, page_hinting >> is enabled and its callbacks are configured along with the max_pages count >> which indicates the maximum number of pages that can be isolated and hinted >> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >> reported. To prevent any false OOM max_pages count is set to 16. >> >> By default page_hinting feature is enabled and gets loaded as soon >> as the virtio-balloon driver is loaded. However, it could be disabled >> by writing the page_hinting_flag which is a virtio-balloon parameter. >> >> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> >> --- >> drivers/virtio/Kconfig | 1 + >> drivers/virtio/virtio_balloon.c | 91 ++++++++++++++++++++++++++++- >> include/uapi/linux/virtio_balloon.h | 11 ++++ >> 3 files changed, 102 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig >> index 023fc3bc01c6..dcc0cb4269a5 100644 >> --- a/drivers/virtio/Kconfig >> +++ b/drivers/virtio/Kconfig >> @@ -47,6 +47,7 @@ config VIRTIO_BALLOON >> tristate "Virtio balloon driver" >> depends on VIRTIO >> select MEMORY_BALLOON >> + select PAGE_HINTING >> ---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 44339fc87cc7..1fb0eb0b2c20 100644 >> --- a/drivers/virtio/virtio_balloon.c >> +++ b/drivers/virtio/virtio_balloon.c >> @@ -18,6 +18,7 @@ >> #include <linux/mm.h> >> #include <linux/mount.h> >> #include <linux/magic.h> >> +#include <linux/page_hinting.h> >> >> /* >> * Balloon device works in 4K page units. So each page is pointed to by >> @@ -35,6 +36,12 @@ >> /* The size of a free page block in bytes */ >> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >> +/* Number of isolated pages to be reported to the host at a time. >> + * TODO: >> + * 1. Set it via host. >> + * 2. Find an optimal value for this. >> + */ >> +#define PAGE_HINTING_MAX_PAGES 16 >> >> #ifdef CONFIG_BALLOON_COMPACTION >> static struct vfsmount *balloon_mnt; >> @@ -45,6 +52,7 @@ enum virtio_balloon_vq { >> VIRTIO_BALLOON_VQ_DEFLATE, >> VIRTIO_BALLOON_VQ_STATS, >> VIRTIO_BALLOON_VQ_FREE_PAGE, >> + VIRTIO_BALLOON_VQ_HINTING, >> VIRTIO_BALLOON_VQ_MAX >> }; >> >> @@ -54,7 +62,8 @@ enum virtio_balloon_config_read { >> >> struct virtio_balloon { >> struct virtio_device *vdev; >> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; >> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, >> + *hinting_vq; >> >> /* Balloon's own wq for cpu-intensive work items */ >> struct workqueue_struct *balloon_wq; >> @@ -112,6 +121,9 @@ struct virtio_balloon { >> >> /* To register a shrinker to shrink memory upon memory pressure */ >> struct shrinker shrinker; >> + >> + /* Array object pointing at the isolated pages ready for hinting */ >> + struct isolated_memory isolated_pages[PAGE_HINTING_MAX_PAGES]; >> }; >> >> static struct virtio_device_id id_table[] = { >> @@ -119,6 +131,66 @@ static struct virtio_device_id id_table[] = { >> { 0 }, >> }; >> >> +static struct page_hinting_config page_hinting_conf; >> +bool page_hinting_flag = true; >> +struct virtio_balloon *hvb; >> +module_param(page_hinting_flag, bool, 0444); >> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >> + >> +static int page_hinting_report(void) >> +{ >> + struct virtqueue *vq = hvb->hinting_vq; >> + struct scatterlist sg; >> + int err = 0, unused; >> + >> + mutex_lock(&hvb->balloon_lock); >> + sg_init_one(&sg, hvb->isolated_pages, sizeof(hvb->isolated_pages[0]) * >> + PAGE_HINTING_MAX_PAGES); >> + err = virtqueue_add_outbuf(vq, &sg, 1, hvb, GFP_KERNEL); > In Alex's patch, I really like it that he's passing pages as sg > entries. IMHO that's both cleaner and allows seamless > support for arbitrary page sizes. > > In particular .... +1. I will also incorporate this change. > >> + if (!err) >> + virtqueue_kick(hvb->hinting_vq); >> + wait_event(hvb->acked, virtqueue_get_buf(vq, &unused)); >> + mutex_unlock(&hvb->balloon_lock); >> + return err; >> +} >> + >> +void hint_pages(struct list_head *pages) >> +{ >> + struct device *dev = &hvb->vdev->dev; >> + struct page *page, *next; >> + int idx = 0, order, err; >> + unsigned long pfn; >> + >> + list_for_each_entry_safe(page, next, pages, lru) { >> + pfn = page_to_pfn(page); >> + order = page_private(page); >> + hvb->isolated_pages[idx].phys_addr = pfn << PAGE_SHIFT; >> + hvb->isolated_pages[idx].size = (1 << order) * PAGE_SIZE; >> + idx++; > ... passing native endian-ness values to host creates pain for > cross-endian configurations. > >> + } >> + err = page_hinting_report(); >> + if (err < 0) >> + dev_err(dev, "Failed to hint pages, err = %d\n", err); >> +} >> + >> +static void page_hinting_init(struct virtio_balloon *vb) >> +{ >> + struct device *dev = &vb->vdev->dev; >> + int err; >> + >> + page_hinting_conf.hint_pages = hint_pages; >> + page_hinting_conf.max_pages = PAGE_HINTING_MAX_PAGES; >> + err = page_hinting_enable(&page_hinting_conf); >> + if (err < 0) { >> + dev_err(dev, "Failed to enable page-hinting, err = %d\n", err); > It would be nicer to disable the feature bit then, or fail probe > completely. Makes sense. Thanks. >> + page_hinting_flag = false; >> + page_hinting_conf.hint_pages = NULL; >> + page_hinting_conf.max_pages = 0; >> + return; >> + } >> + hvb = vb; >> +} >> + >> static u32 page_to_balloon_pfn(struct page *page) >> { >> unsigned long pfn = page_to_pfn(page); >> @@ -475,6 +547,7 @@ 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_HINTING] = NULL; >> >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { >> names[VIRTIO_BALLOON_VQ_STATS] = "stats"; >> @@ -486,11 +559,18 @@ static int init_vqs(struct virtio_balloon *vb) >> callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; >> } >> >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { >> + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; >> + callbacks[VIRTIO_BALLOON_VQ_HINTING] = 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_HINTING)) >> + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; >> + >> 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)) { >> @@ -929,6 +1009,9 @@ static int virtballoon_probe(struct virtio_device *vdev) >> if (err) >> goto out_del_balloon_wq; >> } >> + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && >> + page_hinting_flag) >> + page_hinting_init(vb); >> virtio_device_ready(vdev); >> >> if (towards_target(vb)) >> @@ -976,6 +1059,10 @@ static void virtballoon_remove(struct virtio_device *vdev) >> destroy_workqueue(vb->balloon_wq); >> } >> >> + if (!page_hinting_flag) { >> + hvb = NULL; >> + page_hinting_disable(); >> + } >> remove_common(vb); >> #ifdef CONFIG_BALLOON_COMPACTION >> if (vb->vb_dev_info.inode) >> @@ -1030,8 +1117,10 @@ static unsigned int features[] = { >> VIRTIO_BALLOON_F_MUST_TELL_HOST, >> VIRTIO_BALLOON_F_STATS_VQ, >> VIRTIO_BALLOON_F_DEFLATE_ON_OOM, >> + VIRTIO_BALLOON_F_HINTING, >> VIRTIO_BALLOON_F_FREE_PAGE_HINT, >> VIRTIO_BALLOON_F_PAGE_POISON, >> + VIRTIO_BALLOON_F_HINTING, >> }; >> >> 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..29eed0ec83d3 100644 >> --- a/include/uapi/linux/virtio_balloon.h >> +++ b/include/uapi/linux/virtio_balloon.h >> @@ -36,6 +36,8 @@ >> #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 */ >> +/* TODO: Find a better name to avoid any confusion with FREE_PAGE_HINT */ >> +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ >> >> /* Size of a PFN in the balloon interface. */ >> #define VIRTIO_BALLOON_PFN_SHIFT 12 >> @@ -108,4 +110,13 @@ struct virtio_balloon_stat { >> __virtio64 val; >> } __attribute__((packed)); >> >> +/* >> + * struct isolated_memory- holds the pages which will be reported to the host. >> + * @phys_add: physical address associated with a page. >> + * @size: total size of memory to be reported. >> + */ >> +struct isolated_memory { >> + __virtio64 phys_addr; >> + __virtio64 size; >> +}; >> #endif /* _LINUX_VIRTIO_BALLOON_H */ >> -- >> 2.21.0
On 7/24/19 3:56 PM, David Hildenbrand wrote: > On 24.07.19 21:47, Michael S. Tsirkin wrote: >> On Wed, Jul 10, 2019 at 03:51:58PM -0400, Nitesh Narayan Lal wrote: >>> Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the >>> host. If it is available and page_hinting_flag is set to true, page_hinting >>> is enabled and its callbacks are configured along with the max_pages count >>> which indicates the maximum number of pages that can be isolated and hinted >>> at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are >>> reported. To prevent any false OOM max_pages count is set to 16. >>> >>> By default page_hinting feature is enabled and gets loaded as soon >>> as the virtio-balloon driver is loaded. However, it could be disabled >>> by writing the page_hinting_flag which is a virtio-balloon parameter. >>> >>> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> >>> --- >>> drivers/virtio/Kconfig | 1 + >>> drivers/virtio/virtio_balloon.c | 91 ++++++++++++++++++++++++++++- >>> include/uapi/linux/virtio_balloon.h | 11 ++++ >>> 3 files changed, 102 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig >>> index 023fc3bc01c6..dcc0cb4269a5 100644 >>> --- a/drivers/virtio/Kconfig >>> +++ b/drivers/virtio/Kconfig >>> @@ -47,6 +47,7 @@ config VIRTIO_BALLOON >>> tristate "Virtio balloon driver" >>> depends on VIRTIO >>> select MEMORY_BALLOON >>> + select PAGE_HINTING >>> ---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 44339fc87cc7..1fb0eb0b2c20 100644 >>> --- a/drivers/virtio/virtio_balloon.c >>> +++ b/drivers/virtio/virtio_balloon.c >>> @@ -18,6 +18,7 @@ >>> #include <linux/mm.h> >>> #include <linux/mount.h> >>> #include <linux/magic.h> >>> +#include <linux/page_hinting.h> >>> >>> /* >>> * Balloon device works in 4K page units. So each page is pointed to by >>> @@ -35,6 +36,12 @@ >>> /* The size of a free page block in bytes */ >>> #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ >>> (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) >>> +/* Number of isolated pages to be reported to the host at a time. >>> + * TODO: >>> + * 1. Set it via host. >>> + * 2. Find an optimal value for this. >>> + */ >>> +#define PAGE_HINTING_MAX_PAGES 16 >>> >>> #ifdef CONFIG_BALLOON_COMPACTION >>> static struct vfsmount *balloon_mnt; >>> @@ -45,6 +52,7 @@ enum virtio_balloon_vq { >>> VIRTIO_BALLOON_VQ_DEFLATE, >>> VIRTIO_BALLOON_VQ_STATS, >>> VIRTIO_BALLOON_VQ_FREE_PAGE, >>> + VIRTIO_BALLOON_VQ_HINTING, >>> VIRTIO_BALLOON_VQ_MAX >>> }; >>> >>> @@ -54,7 +62,8 @@ enum virtio_balloon_config_read { >>> >>> struct virtio_balloon { >>> struct virtio_device *vdev; >>> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; >>> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, >>> + *hinting_vq; >>> >>> /* Balloon's own wq for cpu-intensive work items */ >>> struct workqueue_struct *balloon_wq; >>> @@ -112,6 +121,9 @@ struct virtio_balloon { >>> >>> /* To register a shrinker to shrink memory upon memory pressure */ >>> struct shrinker shrinker; >>> + >>> + /* Array object pointing at the isolated pages ready for hinting */ >>> + struct isolated_memory isolated_pages[PAGE_HINTING_MAX_PAGES]; >>> }; >>> >>> static struct virtio_device_id id_table[] = { >>> @@ -119,6 +131,66 @@ static struct virtio_device_id id_table[] = { >>> { 0 }, >>> }; >>> >>> +static struct page_hinting_config page_hinting_conf; >>> +bool page_hinting_flag = true; >>> +struct virtio_balloon *hvb; >>> +module_param(page_hinting_flag, bool, 0444); >>> +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); >>> + >>> +static int page_hinting_report(void) >>> +{ >>> + struct virtqueue *vq = hvb->hinting_vq; >>> + struct scatterlist sg; >>> + int err = 0, unused; >>> + >>> + mutex_lock(&hvb->balloon_lock); >>> + sg_init_one(&sg, hvb->isolated_pages, sizeof(hvb->isolated_pages[0]) * >>> + PAGE_HINTING_MAX_PAGES); >>> + err = virtqueue_add_outbuf(vq, &sg, 1, hvb, GFP_KERNEL); >> In Alex's patch, I really like it that he's passing pages as sg >> entries. IMHO that's both cleaner and allows seamless >> support for arbitrary page sizes. >> > +1 > > I especially like passing full addresses and sizes instead of PFNs and > orders (compared to Alex's v1, where he would pass PFNs and orders). I agree it fixes the issues which could have been introduced due to different page sizes in the host and the guest. >
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig index 023fc3bc01c6..dcc0cb4269a5 100644 --- a/drivers/virtio/Kconfig +++ b/drivers/virtio/Kconfig @@ -47,6 +47,7 @@ config VIRTIO_BALLOON tristate "Virtio balloon driver" depends on VIRTIO select MEMORY_BALLOON + select PAGE_HINTING ---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 44339fc87cc7..1fb0eb0b2c20 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -18,6 +18,7 @@ #include <linux/mm.h> #include <linux/mount.h> #include <linux/magic.h> +#include <linux/page_hinting.h> /* * Balloon device works in 4K page units. So each page is pointed to by @@ -35,6 +36,12 @@ /* The size of a free page block in bytes */ #define VIRTIO_BALLOON_FREE_PAGE_SIZE \ (1 << (VIRTIO_BALLOON_FREE_PAGE_ORDER + PAGE_SHIFT)) +/* Number of isolated pages to be reported to the host at a time. + * TODO: + * 1. Set it via host. + * 2. Find an optimal value for this. + */ +#define PAGE_HINTING_MAX_PAGES 16 #ifdef CONFIG_BALLOON_COMPACTION static struct vfsmount *balloon_mnt; @@ -45,6 +52,7 @@ enum virtio_balloon_vq { VIRTIO_BALLOON_VQ_DEFLATE, VIRTIO_BALLOON_VQ_STATS, VIRTIO_BALLOON_VQ_FREE_PAGE, + VIRTIO_BALLOON_VQ_HINTING, VIRTIO_BALLOON_VQ_MAX }; @@ -54,7 +62,8 @@ enum virtio_balloon_config_read { struct virtio_balloon { struct virtio_device *vdev; - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq; + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq, + *hinting_vq; /* Balloon's own wq for cpu-intensive work items */ struct workqueue_struct *balloon_wq; @@ -112,6 +121,9 @@ struct virtio_balloon { /* To register a shrinker to shrink memory upon memory pressure */ struct shrinker shrinker; + + /* Array object pointing at the isolated pages ready for hinting */ + struct isolated_memory isolated_pages[PAGE_HINTING_MAX_PAGES]; }; static struct virtio_device_id id_table[] = { @@ -119,6 +131,66 @@ static struct virtio_device_id id_table[] = { { 0 }, }; +static struct page_hinting_config page_hinting_conf; +bool page_hinting_flag = true; +struct virtio_balloon *hvb; +module_param(page_hinting_flag, bool, 0444); +MODULE_PARM_DESC(page_hinting_flag, "Enable page hinting"); + +static int page_hinting_report(void) +{ + struct virtqueue *vq = hvb->hinting_vq; + struct scatterlist sg; + int err = 0, unused; + + mutex_lock(&hvb->balloon_lock); + sg_init_one(&sg, hvb->isolated_pages, sizeof(hvb->isolated_pages[0]) * + PAGE_HINTING_MAX_PAGES); + err = virtqueue_add_outbuf(vq, &sg, 1, hvb, GFP_KERNEL); + if (!err) + virtqueue_kick(hvb->hinting_vq); + wait_event(hvb->acked, virtqueue_get_buf(vq, &unused)); + mutex_unlock(&hvb->balloon_lock); + return err; +} + +void hint_pages(struct list_head *pages) +{ + struct device *dev = &hvb->vdev->dev; + struct page *page, *next; + int idx = 0, order, err; + unsigned long pfn; + + list_for_each_entry_safe(page, next, pages, lru) { + pfn = page_to_pfn(page); + order = page_private(page); + hvb->isolated_pages[idx].phys_addr = pfn << PAGE_SHIFT; + hvb->isolated_pages[idx].size = (1 << order) * PAGE_SIZE; + idx++; + } + err = page_hinting_report(); + if (err < 0) + dev_err(dev, "Failed to hint pages, err = %d\n", err); +} + +static void page_hinting_init(struct virtio_balloon *vb) +{ + struct device *dev = &vb->vdev->dev; + int err; + + page_hinting_conf.hint_pages = hint_pages; + page_hinting_conf.max_pages = PAGE_HINTING_MAX_PAGES; + err = page_hinting_enable(&page_hinting_conf); + if (err < 0) { + dev_err(dev, "Failed to enable page-hinting, err = %d\n", err); + page_hinting_flag = false; + page_hinting_conf.hint_pages = NULL; + page_hinting_conf.max_pages = 0; + return; + } + hvb = vb; +} + static u32 page_to_balloon_pfn(struct page *page) { unsigned long pfn = page_to_pfn(page); @@ -475,6 +547,7 @@ 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_HINTING] = NULL; if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) { names[VIRTIO_BALLOON_VQ_STATS] = "stats"; @@ -486,11 +559,18 @@ static int init_vqs(struct virtio_balloon *vb) callbacks[VIRTIO_BALLOON_VQ_FREE_PAGE] = NULL; } + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING)) { + names[VIRTIO_BALLOON_VQ_HINTING] = "hinting_vq"; + callbacks[VIRTIO_BALLOON_VQ_HINTING] = 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_HINTING)) + vb->hinting_vq = vqs[VIRTIO_BALLOON_VQ_HINTING]; + 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)) { @@ -929,6 +1009,9 @@ static int virtballoon_probe(struct virtio_device *vdev) if (err) goto out_del_balloon_wq; } + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_HINTING) && + page_hinting_flag) + page_hinting_init(vb); virtio_device_ready(vdev); if (towards_target(vb)) @@ -976,6 +1059,10 @@ static void virtballoon_remove(struct virtio_device *vdev) destroy_workqueue(vb->balloon_wq); } + if (!page_hinting_flag) { + hvb = NULL; + page_hinting_disable(); + } remove_common(vb); #ifdef CONFIG_BALLOON_COMPACTION if (vb->vb_dev_info.inode) @@ -1030,8 +1117,10 @@ static unsigned int features[] = { VIRTIO_BALLOON_F_MUST_TELL_HOST, VIRTIO_BALLOON_F_STATS_VQ, VIRTIO_BALLOON_F_DEFLATE_ON_OOM, + VIRTIO_BALLOON_F_HINTING, VIRTIO_BALLOON_F_FREE_PAGE_HINT, VIRTIO_BALLOON_F_PAGE_POISON, + VIRTIO_BALLOON_F_HINTING, }; 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..29eed0ec83d3 100644 --- a/include/uapi/linux/virtio_balloon.h +++ b/include/uapi/linux/virtio_balloon.h @@ -36,6 +36,8 @@ #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 */ +/* TODO: Find a better name to avoid any confusion with FREE_PAGE_HINT */ +#define VIRTIO_BALLOON_F_HINTING 5 /* Page hinting virtqueue */ /* Size of a PFN in the balloon interface. */ #define VIRTIO_BALLOON_PFN_SHIFT 12 @@ -108,4 +110,13 @@ struct virtio_balloon_stat { __virtio64 val; } __attribute__((packed)); +/* + * struct isolated_memory- holds the pages which will be reported to the host. + * @phys_add: physical address associated with a page. + * @size: total size of memory to be reported. + */ +struct isolated_memory { + __virtio64 phys_addr; + __virtio64 size; +}; #endif /* _LINUX_VIRTIO_BALLOON_H */
Enables the kernel to negotiate VIRTIO_BALLOON_F_HINTING feature with the host. If it is available and page_hinting_flag is set to true, page_hinting is enabled and its callbacks are configured along with the max_pages count which indicates the maximum number of pages that can be isolated and hinted at a time. Currently, only free pages of order >= (MAX_ORDER - 2) are reported. To prevent any false OOM max_pages count is set to 16. By default page_hinting feature is enabled and gets loaded as soon as the virtio-balloon driver is loaded. However, it could be disabled by writing the page_hinting_flag which is a virtio-balloon parameter. Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com> --- drivers/virtio/Kconfig | 1 + drivers/virtio/virtio_balloon.c | 91 ++++++++++++++++++++++++++++- include/uapi/linux/virtio_balloon.h | 11 ++++ 3 files changed, 102 insertions(+), 1 deletion(-)