diff options
Diffstat (limited to 'hw/virtio/virtio-balloon.c')
| -rw-r--r-- | hw/virtio/virtio-balloon.c | 115 |
1 files changed, 55 insertions, 60 deletions
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index e85d1c0d5c..25de154307 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -34,31 +34,53 @@ #define BALLOON_PAGE_SIZE (1 << VIRTIO_BALLOON_PFN_SHIFT) -struct PartiallyBalloonedPage { - RAMBlock *rb; - ram_addr_t base; - unsigned long bitmap[]; -}; +typedef struct PartiallyBalloonedPage { + ram_addr_t base_gpa; + unsigned long *bitmap; +} PartiallyBalloonedPage; + +static void virtio_balloon_pbp_free(PartiallyBalloonedPage *pbp) +{ + if (!pbp->bitmap) { + return; + } + g_free(pbp->bitmap); + pbp->bitmap = NULL; +} + +static void virtio_balloon_pbp_alloc(PartiallyBalloonedPage *pbp, + ram_addr_t base_gpa, + long subpages) +{ + pbp->base_gpa = base_gpa; + pbp->bitmap = bitmap_new(subpages); +} + +static bool virtio_balloon_pbp_matches(PartiallyBalloonedPage *pbp, + ram_addr_t base_gpa) +{ + return pbp->base_gpa == base_gpa; +} static void balloon_inflate_page(VirtIOBalloon *balloon, - MemoryRegion *mr, hwaddr offset) + MemoryRegion *mr, hwaddr mr_offset, + PartiallyBalloonedPage *pbp) { - void *addr = memory_region_get_ram_ptr(mr) + offset; + 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; - ram_addr_t ram_offset, host_page_base; /* XXX is there a better way to get to the RAMBlock than via a * host address? */ - rb = qemu_ram_block_from_host(addr, false, &ram_offset); + rb = qemu_ram_block_from_host(addr, false, &rb_offset); rb_page_size = qemu_ram_pagesize(rb); - host_page_base = ram_offset & ~(rb_page_size - 1); if (rb_page_size == BALLOON_PAGE_SIZE) { /* Easy case */ - ram_block_discard_range(rb, ram_offset, rb_page_size); + ram_block_discard_range(rb, rb_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 */ @@ -74,81 +96,51 @@ static void balloon_inflate_page(VirtIOBalloon *balloon, warn_report_once( "Balloon used with backing page size > 4kiB, this may not be reliable"); + 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 - || host_page_base != balloon->pbp->base)) { + 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 */ - g_free(balloon->pbp); - balloon->pbp = NULL; + virtio_balloon_pbp_free(pbp); } - 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 = host_page_base; + if (!pbp->bitmap) { + virtio_balloon_pbp_alloc(pbp, base_gpa, subpages); } - bitmap_set(balloon->pbp->bitmap, - (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, - subpages); + 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); } } static void balloon_deflate_page(VirtIOBalloon *balloon, - MemoryRegion *mr, hwaddr offset) + MemoryRegion *mr, hwaddr mr_offset) { - void *addr = memory_region_get_ram_ptr(mr) + offset; + void *addr = memory_region_get_ram_ptr(mr) + mr_offset; + ram_addr_t rb_offset; RAMBlock *rb; size_t rb_page_size; - ram_addr_t ram_offset, host_page_base; void *host_addr; int ret; /* XXX is there a better way to get to the RAMBlock than via a * host address? */ - rb = qemu_ram_block_from_host(addr, false, &ram_offset); + rb = qemu_ram_block_from_host(addr, false, &rb_offset); rb_page_size = qemu_ram_pagesize(rb); - host_page_base = ram_offset & ~(rb_page_size - 1); - - if (balloon->pbp - && rb == balloon->pbp->rb - && host_page_base == balloon->pbp->base) { - int subpages = rb_page_size / BALLOON_PAGE_SIZE; - - /* - * This means the guest has asked to discard some of the 4kiB - * subpages of a host page, but then changed its mind and - * asked to keep them after all. It's exceedingly unlikely - * for a guest to do this in practice, but handle it anyway, - * since getting it wrong could mean discarding memory the - * guest is still using. */ - bitmap_clear(balloon->pbp->bitmap, - (ram_offset - balloon->pbp->base) / BALLOON_PAGE_SIZE, - subpages); - - if (bitmap_empty(balloon->pbp->bitmap, subpages)) { - g_free(balloon->pbp); - balloon->pbp = NULL; - } - } host_addr = (void *)((uintptr_t)addr & ~(rb_page_size - 1)); @@ -335,16 +327,18 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) MemoryRegionSection section; for (;;) { + PartiallyBalloonedPage pbp = {}; size_t offset = 0; uint32_t pfn; + elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); if (!elem) { - return; + break; } while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) { + unsigned int p = virtio_ldl_p(vdev, &pfn); hwaddr pa; - int p = virtio_ldl_p(vdev, &pfn); pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT; offset += 4; @@ -368,7 +362,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) if (!qemu_balloon_is_inhibited()) { if (vq == s->ivq) { balloon_inflate_page(s, section.mr, - section.offset_within_region); + section.offset_within_region, &pbp); } else if (vq == s->dvq) { balloon_deflate_page(s, section.mr, section.offset_within_region); } else { @@ -381,6 +375,7 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq) virtqueue_push(vq, elem, offset); virtio_notify(vdev, vq); g_free(elem); + virtio_balloon_pbp_free(&pbp); } } |