Re: [PATCH for QEMU v2] virtio-balloon: Add option cont-pages to set VIRTIO_BALLOON_VQ_INFLATE_CONT

[teawater]

Ping.

Thanks,
Hui

> 2020年3月23日 00:04，Hui Zhu <address@hidden> 写道：
> 
> If the guest kernel has many fragmentation pages, use virtio_balloon
> will split THP of QEMU when it calls MADV_DONTNEED madvise to release
> the balloon pages.
> Set option cont-pages to on will open flags VIRTIO_BALLOON_VQ_INFLATE_CONT
> and set continuous pages order to THP order.
> Then It will get continuous pages PFN from VQ icvq use use madvise
> MADV_DONTNEED release the THP page.
> This will handle the THP split issue.
> 
> Signed-off-by: Hui Zhu <address@hidden>
> ---
> hw/virtio/virtio-balloon.c                      | 32 +++++++++++++++++++++----
> include/hw/virtio/virtio-balloon.h              |  4 +++-
> include/standard-headers/linux/virtio_balloon.h |  4 ++++
> 3 files changed, 35 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index a4729f7..88bdaca 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -34,6 +34,7 @@
> #include "hw/virtio/virtio-access.h"
> 
> #define BALLOON_PAGE_SIZE  (1 << VIRTIO_BALLOON_PFN_SHIFT)
> +#define CONT_PAGES_ORDER   9
> 
> typedef struct PartiallyBalloonedPage {
>     ram_addr_t base_gpa;
> @@ -65,7 +66,8 @@ static bool 
> virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
> 
> static void balloon_inflate_page(VirtIOBalloon *balloon,
>                                  MemoryRegion *mr, hwaddr mr_offset,
> -                                 PartiallyBalloonedPage *pbp)
> +                                 PartiallyBalloonedPage *pbp, 
> +                                 bool is_cont_pages)
> {
>     void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
>     ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
> @@ -76,6 +78,13 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
>     /* XXX is there a better way to get to the RAMBlock than via a
>      * host address? */
>     rb = qemu_ram_block_from_host(addr, false, &rb_offset);
> +
> +    if (is_cont_pages) {
> +        ram_block_discard_range(rb, rb_offset,
> +                                BALLOON_PAGE_SIZE << CONT_PAGES_ORDER);
> +        return;
> +    }
> +
>     rb_page_size = qemu_ram_pagesize(rb);
> 
>     if (rb_page_size == BALLOON_PAGE_SIZE) {
> @@ -361,9 +370,10 @@ static void virtio_balloon_handle_output(VirtIODevice 
> *vdev, VirtQueue *vq)
>             trace_virtio_balloon_handle_output(memory_region_name(section.mr),
>                                                pa);
>             if (!qemu_balloon_is_inhibited()) {
> -                if (vq == s->ivq) {
> +                if (vq == s->ivq || vq == s->icvq) {
>                     balloon_inflate_page(s, section.mr,
> -                                         section.offset_within_region, &pbp);
> +                                         section.offset_within_region, &pbp,
> +                                         vq == s->icvq);
>                 } else if (vq == s->dvq) {
>                     balloon_deflate_page(s, section.mr, 
> section.offset_within_region);
>                 } else {
> @@ -618,9 +628,12 @@ static size_t virtio_balloon_config_size(VirtIOBalloon 
> *s)
>     if (s->qemu_4_0_config_size) {
>         return sizeof(struct virtio_balloon_config);
>     }
> -    if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) {
> +    if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) {
>         return sizeof(struct virtio_balloon_config);
>     }
> +    if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) {
> +        return offsetof(struct virtio_balloon_config, pages_order);
> +    }
>     if (virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) {
>         return offsetof(struct virtio_balloon_config, poison_val);
>     }
> @@ -646,6 +659,10 @@ static void virtio_balloon_get_config(VirtIODevice 
> *vdev, uint8_t *config_data)
>                        cpu_to_le32(VIRTIO_BALLOON_CMD_ID_DONE);
>     }
> 
> +    if (virtio_has_feature(dev->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) 
> {
> +        config.pages_order = cpu_to_le32(CONT_PAGES_ORDER);
> +    }
> +
>     trace_virtio_balloon_get_config(config.num_pages, config.actual);
>     memcpy(config_data, &config, virtio_balloon_config_size(dev));
> }
> @@ -816,6 +833,11 @@ static void virtio_balloon_device_realize(DeviceState 
> *dev, Error **errp)
>             virtio_error(vdev, "iothread is missing");
>         }
>     }
> +
> +    if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) {
> +        s->icvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
> +    }
> +
>     reset_stats(s);
> }
> 
> @@ -916,6 +938,8 @@ static Property virtio_balloon_properties[] = {
>                     VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false),
>     DEFINE_PROP_BIT("free-page-hint", VirtIOBalloon, host_features,
>                     VIRTIO_BALLOON_F_FREE_PAGE_HINT, false),
> +    DEFINE_PROP_BIT("cont-pages", VirtIOBalloon, host_features,
> +                    VIRTIO_BALLOON_F_CONT_PAGES, false),
>     /* QEMU 4.0 accidentally changed the config size even when free-page-hint
>      * is disabled, resulting in QEMU 3.1 migration incompatibility.  This
>      * property retains this quirk for QEMU 4.1 machine types.
> diff --git a/include/hw/virtio/virtio-balloon.h 
> b/include/hw/virtio/virtio-balloon.h
> index d1c968d..61d2419 100644
> --- a/include/hw/virtio/virtio-balloon.h
> +++ b/include/hw/virtio/virtio-balloon.h
> @@ -42,7 +42,7 @@ enum virtio_balloon_free_page_report_status {
> 
> typedef struct VirtIOBalloon {
>     VirtIODevice parent_obj;
> -    VirtQueue *ivq, *dvq, *svq, *free_page_vq;
> +    VirtQueue *ivq, *dvq, *svq, *free_page_vq, *icvq;
>     uint32_t free_page_report_status;
>     uint32_t num_pages;
>     uint32_t actual;
> @@ -70,6 +70,8 @@ typedef struct VirtIOBalloon {
>     uint32_t host_features;
> 
>     bool qemu_4_0_config_size;
> +
> +    uint32_t pages_order;
> } VirtIOBalloon;
> 
> #endif
> diff --git a/include/standard-headers/linux/virtio_balloon.h 
> b/include/standard-headers/linux/virtio_balloon.h
> index 9375ca2..ee18be7 100644
> --- a/include/standard-headers/linux/virtio_balloon.h
> +++ b/include/standard-headers/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 */
> +#define VIRTIO_BALLOON_F_CONT_PAGES  5 /* VQ to report continuous pages */
> +
> 
> /* Size of a PFN in the balloon interface. */
> #define VIRTIO_BALLOON_PFN_SHIFT 12
> @@ -51,6 +53,8 @@ struct virtio_balloon_config {
>       uint32_t free_page_report_cmd_id;
>       /* Stores PAGE_POISON if page poisoning is in use */
>       uint32_t poison_val;
> +     /* Pages order if VIRTIO_BALLOON_F_CONT_PAGES is set */
> +     uint32_t pages_order;
> };
> 
> #define VIRTIO_BALLOON_S_SWAP_IN  0   /* Amount of memory swapped in */
> -- 
> 2.7.4
>