From: David Hildenbrand <da...@redhat.com> In case we don't have an iothread, we mark the feature as abscent but still add the queue. 'free_page_bh' remains set to NULL.
qemu-system-i386 \ -M microvm \ -nographic \ -device virtio-balloon-device,free-page-hint=true \ -nographic \ -display none \ -monitor none \ -serial none \ -qtest stdio Doing a "write 0xc0000e30 0x24 0x030000000300000003000000030000000300000003000000030000000300000003000000" We will trigger a SEGFAULT. Let's move the check and bail out. While at it, move the static initializations to instance_init(). free_page_report_status and block_iothread are implicitly set to the right values (0/false) already, so drop the initialization. Reviewed-by: Alexander Duyck <alexander.h.du...@linux.intel.com> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT") Reported-by: Alexander Bulekov <alx...@bu.edu> Cc: qemu-sta...@nongnu.org Cc: Wei Wang <wei.w.w...@intel.com> Cc: Michael S. Tsirkin <m...@redhat.com> Cc: Philippe Mathieu-Daudé <phi...@redhat.com> Cc: Alexander Duyck <alexander.du...@gmail.com> Signed-off-by: David Hildenbrand <da...@redhat.com> Message-Id: <20200520100439.19872-2-da...@redhat.com> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> (cherry picked from commit 12fc8903a8ee09fb5f642de82699a0b211e1b5a7) Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> --- hw/virtio/virtio-balloon.c | 33 ++++++++++++++++----------------- 1 file changed, 16 insertions(+), 17 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index 40b04f5180..8c6a177365 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -789,6 +789,13 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) return; } + if (virtio_has_feature(s->host_features, VIRTIO_BALLOON_F_FREE_PAGE_HINT) && + !s->iothread) { + error_setg(errp, "'free-page-hint' requires 'iothread' to be set"); + virtio_cleanup(vdev); + return; + } + s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output); s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats); @@ -797,24 +804,11 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { s->free_page_vq = virtio_add_queue(vdev, VIRTQUEUE_MAX_SIZE, virtio_balloon_handle_free_page_vq); - s->free_page_report_status = FREE_PAGE_REPORT_S_STOP; - s->free_page_report_cmd_id = - VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; - s->free_page_report_notify.notify = - virtio_balloon_free_page_report_notify; precopy_add_notifier(&s->free_page_report_notify); - if (s->iothread) { - object_ref(OBJECT(s->iothread)); - s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread), - virtio_ballloon_get_free_page_hints, s); - qemu_mutex_init(&s->free_page_lock); - qemu_cond_init(&s->free_page_cond); - s->block_iothread = false; - } else { - /* Simply disable this feature if the iothread wasn't created. */ - s->host_features &= ~(1 << VIRTIO_BALLOON_F_FREE_PAGE_HINT); - virtio_error(vdev, "iothread is missing"); - } + + object_ref(OBJECT(s->iothread)); + s->free_page_bh = aio_bh_new(iothread_get_aio_context(s->iothread), + virtio_ballloon_get_free_page_hints, s); } reset_stats(s); } @@ -885,6 +879,11 @@ static void virtio_balloon_instance_init(Object *obj) { VirtIOBalloon *s = VIRTIO_BALLOON(obj); + qemu_mutex_init(&s->free_page_lock); + qemu_cond_init(&s->free_page_cond); + s->free_page_report_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_CMD_ID_MIN; + s->free_page_report_notify.notify = virtio_balloon_free_page_report_notify; + object_property_add(obj, "guest-stats", "guest statistics", balloon_stats_get_all, NULL, NULL, s, NULL); -- 2.17.1