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Subject[RFC for qemu v4 2/2] virtio_balloon: Add dcvq to deflate continuous pages
Date
This commit adds a vq dcvq to deflate continuous pages.
When VIRTIO_BALLOON_F_CONT_PAGES is set, try to get continuous pages
from icvq and use madvise MADV_WILLNEED with the pages.

Signed-off-by: Hui Zhu <teawaterz@linux.alibaba.com>
---
hw/virtio/virtio-balloon.c | 14 +++++++++-----
include/hw/virtio/virtio-balloon.h | 2 +-
2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index d36a5c8..165adf7 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -138,7 +138,8 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
}

static void balloon_deflate_page(VirtIOBalloon *balloon,
- MemoryRegion *mr, hwaddr mr_offset)
+ MemoryRegion *mr, hwaddr mr_offset,
+ size_t size)
{
void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
ram_addr_t rb_offset;
@@ -153,10 +154,11 @@ static void balloon_deflate_page(VirtIOBalloon *balloon,
rb_page_size = qemu_ram_pagesize(rb);

host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1));
+ size &= ~(rb_page_size - 1);

/* When a page is deflated, we hint the whole host page it lives
* on, since we can't do anything smaller */
- ret = qemu_madvise(host_addr, rb_page_size, QEMU_MADV_WILLNEED);
+ ret = qemu_madvise(host_addr, size, QEMU_MADV_WILLNEED);
if (ret != 0) {
warn_report("Couldn't MADV_WILLNEED on balloon deflate: %s",
strerror(errno));
@@ -354,7 +356,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
offset += 4;

- if (vq == s->icvq) {
+ if (vq == s->icvq || vq == s->dcvq) {
uint32_t psize_ptr;
if (iov_to_buf(elem->out_sg, elem->out_num, offset, &psize_ptr, 4) != 4) {
break;
@@ -383,8 +385,9 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
balloon_inflate_page(s, section.mr,
section.offset_within_region,
psize, &pbp);
- } else if (vq == s->dvq) {
- balloon_deflate_page(s, section.mr, section.offset_within_region);
+ } else if (vq == s->dvq || vq == s->dcvq) {
+ balloon_deflate_page(s, section.mr, section.offset_within_region,
+ psize);
} else {
g_assert_not_reached();
}
@@ -838,6 +841,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)

if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_CONT_PAGES)) {
s->icvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
+ s->dcvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
}

reset_stats(s);
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index 6a2514d..848a7fb 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, *icvq;
+ VirtQueue *ivq, *dvq, *svq, *free_page_vq, *icvq, *dcvq;
uint32_t free_page_report_status;
uint32_t num_pages;
uint32_t actual;
--
2.7.4
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