diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index f206cc8bf7..40d493a31a 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -35,16 +35,44 @@ #define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT) struct PartiallyBalloonedPage { - RAMBlock *rb; - ram_addr_t base; - unsigned long bitmap[]; + ram_addr_t base_gpa; + long subpages; + unsigned long *bitmap; }; +static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp) +{ + if (!pbp) { + return; + } + g_free(pbp->bitmap); + g_free(pbp); +} + +static PartiallyBalloonedPage *virtio_balloon_pbp_alloc(ram_addr_t base_gpa, + long subpages) +{ + PartiallyBalloonedPage *pbp = g_new0(PartiallyBalloonedPage, 1); + + pbp->base_gpa = base_gpa; + pbp->subpages = subpages; + pbp->bitmap = bitmap_new(subpages); + + return pbp; +} + +static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp, + ram_addr_t base_gpa, long subpages) +{ + return pbp->subpages == subpages && pbp->base_gpa == base_gpa; +} + static void balloon_inflate_page(VirtIOBalloon *balloon, MemoryRegion *mr, hwaddr mr_offset) { void *addr = memory_region_get_ram_ptr(mr) + mr_offset; - ram_addr_t rb_offset, rb_aligned_offset; + ram_addr_t rb_offset, rb_aligned_offset, base_gpa; + PartiallyBalloonedPage **pbp = &balloon->pbp; RAMBlock *rb; size_t rb_page_size; int subpages; @@ -75,39 +103,34 @@ 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 (balloon->pbp - && (rb != balloon->pbp->rb - || rb_aligned_offset != balloon->pbp->base)) { + if (*pbp && !virtio_balloon_pbp_matches(*pbp, base_gpa, subpages)) { /* 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 */ - g_free(balloon->pbp); - balloon->pbp = NULL; + virtio_balloon_pbp_free(*pbp); + *pbp = NULL; } - if (!balloon->pbp) { - /* Starting on a new host page */ - size_t bitlen = BITS_TO_LONGS(subpages) * sizeof(unsigned long); - balloon->pbp = g_malloc0(sizeof(PartiallyBalloonedPage) + bitlen); - balloon->pbp->rb = rb; - balloon->pbp->base = rb_aligned_offset; + if (!*pbp) { + *pbp = virtio_balloon_pbp_alloc(base_gpa, subpages); } - set_bit((rb_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, - balloon->pbp->bitmap); + set_bit((rb_offset - rb_aligned_offset) / BALLOON_PAGE_SIZE, + (*pbp)->bitmap); - if (bitmap_full(balloon->pbp->bitmap, subpages)) { + if (bitmap_full((*pbp)->bitmap, subpages)) { /* We've accumulated a full host page, we can actually discard * it now */ - ram_block_discard_range(rb, balloon->pbp->base, rb_page_size); + 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 */ - - g_free(balloon->pbp); - balloon->pbp = NULL; + virtio_balloon_pbp_free(*pbp); + *pbp = NULL; } } @@ -128,7 +151,7 @@ static void balloon_deflate_page(VirtIOBalloon *balloon, if (balloon->pbp) { /* Let's play safe and always reset the pbp on deflation requests. */ - g_free(balloon->pbp); + virtio_balloon_pbp_free(balloon->pbp); balloon->pbp = NULL; }