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Date: Thu, 16 Jul 2020 10:41:54 +0800
From: Hui Zhu <teawater@...il.com>
To: mst@...hat.com, david@...hat.com, jasowang@...hat.com,
akpm@...ux-foundation.org,
virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
qemu-devel@...gnu.org, virtio-dev@...ts.oasis-open.org
Cc: Hui Zhu <teawater@...il.com>, Hui Zhu <teawaterz@...ux.alibaba.com>
Subject: [RFC for qemu v4 1/2] virtio_balloon: Add cont-pages and icvq
This commit adds cont-pages option to virtio_balloon. virtio_balloon
will open flags VIRTIO_BALLOON_F_CONT_PAGES with this option.
And it add a vq icvq to inflate continuous pages.
When VIRTIO_BALLOON_F_CONT_PAGES is set, try to get continuous pages
from icvq and use madvise MADV_DONTNEED release the pages.
Signed-off-by: Hui Zhu <teawaterz@...ux.alibaba.com>
---
hw/virtio/virtio-balloon.c | 80 ++++++++++++++++---------
include/hw/virtio/virtio-balloon.h | 2 +-
include/standard-headers/linux/virtio_balloon.h | 1 +
3 files changed, 55 insertions(+), 28 deletions(-)
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index a4729f7..d36a5c8 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -65,23 +65,26 @@ static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp,
static void balloon_inflate_page(VirtIOBalloon *balloon,
MemoryRegion *mr, hwaddr mr_offset,
+ size_t size,
PartiallyBalloonedPage *pbp)
{
void *addr = memory_region_get_ram_ptr(mr) + mr_offset;
ram_addr_t rb_offset, rb_aligned_offset, base_gpa;
RAMBlock *rb;
size_t rb_page_size;
- int subpages;
+ int subpages, pages_num;
/* 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);
rb_page_size = qemu_ram_pagesize(rb);
+ size &= ~(rb_page_size - 1);
+
if (rb_page_size == BALLOON_PAGE_SIZE) {
/* Easy case */
- ram_block_discard_range(rb, rb_offset, rb_page_size);
+ ram_block_discard_range(rb, rb_offset, size);
/* We ignore errors from ram_block_discard_range(), because it
* has already reported them, and failing to discard a balloon
* page is not fatal */
@@ -99,32 +102,38 @@ static void balloon_inflate_page(VirtIOBalloon *balloon,
rb_aligned_offset = QEMU_ALIGN_DOWN(rb_offset, rb_page_size);
subpages = rb_page_size / BALLOON_PAGE_SIZE;
- base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
- (rb_offset - rb_aligned_offset);
- if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
- /* We've partially ballooned part of a host page, but now
- * we're trying to balloon part of a different one. Too hard,
- * give up on the old partial page */
- virtio_balloon_pbp_free(pbp);
- }
+ for (pages_num = size / BALLOON_PAGE_SIZE;
+ pages_num > 0; pages_num--) {
+ base_gpa = memory_region_get_ram_addr(mr) + mr_offset -
+ (rb_offset - rb_aligned_offset);
- if (!pbp->bitmap) {
- virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
- }
+ if (pbp->bitmap && !virtio_balloon_pbp_matches(pbp, base_gpa)) {
+ /* We've partially ballooned part of a host page, but now
+ * we're trying to balloon part of a different one. Too hard,
+ * give up on the old partial page */
+ virtio_balloon_pbp_free(pbp);
+ }
- set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
- pbp->bitmap);
+ if (!pbp->bitmap) {
+ virtio_balloon_pbp_alloc(pbp, base_gpa, subpages);
+ }
- if (bitmap_full(pbp->bitmap, subpages)) {
- /* We've accumulated a full host page, we can actually discard
- * it now */
+ set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE,
+ pbp->bitmap);
- ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
- /* We ignore errors from ram_block_discard_range(), because it
- * has already reported them, and failing to discard a balloon
- * page is not fatal */
- virtio_balloon_pbp_free(pbp);
+ if (bitmap_full(pbp->bitmap, subpages)) {
+ /* We've accumulated a full host page, we can actually discard
+ * it now */
+
+ ram_block_discard_range(rb, rb_aligned_offset, rb_page_size);
+ /* We ignore errors from ram_block_discard_range(), because it
+ * has already reported them, and failing to discard a balloon
+ * page is not fatal */
+ virtio_balloon_pbp_free(pbp);
+ }
+
+ mr_offset += BALLOON_PAGE_SIZE;
}
}
@@ -340,12 +349,21 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
unsigned int p = virtio_ldl_p(vdev, &pfn);
hwaddr pa;
+ unsigned int psize = BALLOON_PAGE_SIZE;
pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
offset += 4;
- section = memory_region_find(get_system_memory(), pa,
- BALLOON_PAGE_SIZE);
+ if (vq == s->icvq) {
+ uint32_t psize_ptr;
+ if (iov_to_buf(elem->out_sg, elem->out_num, offset, &psize_ptr, 4) != 4) {
+ break;
+ }
+ psize = virtio_ldl_p(vdev, &psize_ptr);
+ offset += 4;
+ }
+
+ section = memory_region_find(get_system_memory(), pa, psize);
if (!section.mr) {
trace_virtio_balloon_bad_addr(pa);
continue;
@@ -361,9 +379,10 @@ 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,
+ psize, &pbp);
} else if (vq == s->dvq) {
balloon_deflate_page(s, section.mr, section.offset_within_region);
} else {
@@ -816,6 +835,11 @@ 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 +940,8 @@ 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..6a2514d 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;
diff --git a/include/standard-headers/linux/virtio_balloon.h b/include/standard-headers/linux/virtio_balloon.h
index 9375ca2..033926c 100644
--- a/include/standard-headers/linux/virtio_balloon.h
+++ b/include/standard-headers/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_CONT_PAGES 6 /* VQ to report continuous pages */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
--
2.7.4
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