On 18.05.20 17:01, Alexander Duyck wrote:
> On Mon, May 18, 2020 at 1:37 AM David Hildenbrand <da...@redhat.com> wrote:
>>
>> 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_initialize().
>>
>> Fixes: c13c4153f76d ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
>> Reported-by: Alexander Bulekov <alx...@bu.edu>
>> 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>
>> ---
>> hw/virtio/virtio-balloon.c | 35 ++++++++++++++++++-----------------
>> 1 file changed, 18 insertions(+), 17 deletions(-)
>>
>> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
>> index 065cd450f1..dc3b1067ab 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);
>> }
>> @@ -892,6 +886,13 @@ 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_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;
>> + s->block_iothread = false;
>> +
>> object_property_add(obj, "guest-stats", "guest statistics",
>> balloon_stats_get_all, NULL, NULL, s);
>>
>
> So the one nit I have is that I am not sure you need to bother with
> initializing block_iothread since it should already be initialized to
> false/0 shouldn't it? Otherwise this all looks good to me.
Yes, and as "FREE_PAGE_REPORT_S_STOP = 0", that's implicitly set as
well. Both can go IMHO.
>
> Reviewed-by: Alexander Duyck <alexander.h.du...@linux.intel.com>
>
Thanks!
--
Thanks,
David / dhildenb
