From: Gavin Shan Date: Thu, 31 Aug 2023 01:10:07 +0000 (+1000) Subject: virtio_balloon: Fix endless deflation and inflation on arm64 X-Git-Tag: v6.6.17~3698^2~4 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=07622bd415639e9709579f400afd19e7e9866e5e;p=platform%2Fkernel%2Flinux-rpi.git virtio_balloon: Fix endless deflation and inflation on arm64 The deflation request to the target, which isn't unaligned to the guest page size causes endless deflation and inflation actions. For example, we receive the flooding QMP events for the changes on memory balloon's size after a deflation request to the unaligned target is sent for the ARM64 guest, where we have 64KB base page size. /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 \ -accel kvm -machine virt,gic-version=host -cpu host \ -smp maxcpus=8,cpus=8,sockets=2,clusters=2,cores=2,threads=1 \ -m 1024M,slots=16,maxmem=64G \ -object memory-backend-ram,id=mem0,size=512M \ -object memory-backend-ram,id=mem1,size=512M \ -numa node,nodeid=0,memdev=mem0,cpus=0-3 \ -numa node,nodeid=1,memdev=mem1,cpus=4-7 \ : \ -device virtio-balloon-pci,id=balloon0,bus=pcie.10 { "execute" : "balloon", "arguments": { "value" : 1073672192 } } {"return": {}} {"timestamp": {"seconds": 1693272173, "microseconds": 88667}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272174, "microseconds": 89704}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272175, "microseconds": 90819}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272176, "microseconds": 91961}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272177, "microseconds": 93040}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} {"timestamp": {"seconds": 1693272178, "microseconds": 94117}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} {"timestamp": {"seconds": 1693272179, "microseconds": 95337}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272180, "microseconds": 96615}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} {"timestamp": {"seconds": 1693272181, "microseconds": 97626}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272182, "microseconds": 98693}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} {"timestamp": {"seconds": 1693272183, "microseconds": 99698}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272184, "microseconds": 100727}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272185, "microseconds": 90430}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} {"timestamp": {"seconds": 1693272186, "microseconds": 102999}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}} : Fix it by aligning the target up to the guest page size, 64KB in this specific case. With this applied, no flooding QMP events are observed and the memory balloon's size can be stablizied to 0x3ffe0000 soon after the deflation request is sent. { "execute" : "balloon", "arguments": { "value" : 1073672192 } } {"return": {}} {"timestamp": {"seconds": 1693273328, "microseconds": 793075}, \ "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}} { "execute" : "query-balloon" } {"return": {"actual": 1073610752}} Cc: stable@vger.kernel.org Signed-off-by: Gavin Shan Tested-by: Zhenyu Zhang Message-Id: <20230831011007.1032822-1-gshan@redhat.com> Signed-off-by: Michael S. Tsirkin Reviewed-by: David Hildenbrand --- diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 5b15936..2d5d252 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -395,7 +395,11 @@ static inline s64 towards_target(struct virtio_balloon *vb) virtio_cread_le(vb->vdev, struct virtio_balloon_config, num_pages, &num_pages); - target = num_pages; + /* + * Aligned up to guest page size to avoid inflating and deflating + * balloon endlessly. + */ + target = ALIGN(num_pages, VIRTIO_BALLOON_PAGES_PER_PAGE); return target - vb->num_pages; }