In order to avoid migration issues, we enable DISCARD and WRITE_ZEROES features only for machine type >= 4.0
As discussed with Michael S. Tsirkin and Stefan Hajnoczi on the list [1], DISCARD operation should not have security implications (eg. page cache attacks), so we can enable it by default. [1] https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg00504.html Suggested-by: Dr. David Alan Gilbert <dgilb...@redhat.com> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com> Signed-off-by: Stefano Garzarella <sgarz...@redhat.com> --- hw/block/virtio-blk.c | 4 ++++ hw/core/machine.c | 2 ++ 2 files changed, 6 insertions(+) diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 938273c63c..6f2e86264d 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -1026,6 +1026,10 @@ static Property virtio_blk_properties[] = { DEFINE_PROP_UINT16("queue-size", VirtIOBlock, conf.queue_size, 128), DEFINE_PROP_LINK("iothread", VirtIOBlock, conf.iothread, TYPE_IOTHREAD, IOThread *), + DEFINE_PROP_BIT64("discard", VirtIOBlock, host_features, + VIRTIO_BLK_F_DISCARD, true), + DEFINE_PROP_BIT64("write-zeroes", VirtIOBlock, host_features, + VIRTIO_BLK_F_WRITE_ZEROES, true), DEFINE_PROP_END_OF_LIST(), }; diff --git a/hw/core/machine.c b/hw/core/machine.c index 077fbd182a..766ca5899d 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -33,6 +33,8 @@ GlobalProperty hw_compat_3_1[] = { { "usb-kbd", "serial", "42" }, { "usb-mouse", "serial", "42" }, { "usb-kbd", "serial", "42" }, + { "virtio-blk-device", "discard", "false" }, + { "virtio-blk-device", "write-zeroes", "false" }, }; const size_t hw_compat_3_1_len = G_N_ELEMENTS(hw_compat_3_1); -- 2.20.1
