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virtio-blk: add "discard" and "write-zeroes" properties 

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 <dgilbert@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20190221103314.58500-4-sgarzare@redhat.com
Message-Id: <20190221103314.58500-4-sgarzare@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefano Garzarella 2019-02-21 11:33:07 +01:00 committed by Stefan Hajnoczi
parent bbe8bd4d85
commit 5c81161f80
2 changed files with 6 additions and 0 deletions
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4
hw/block/virtio-blk.c
View File

@ -1027,6 +1027,10 @@ 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(),
};

2
hw/core/machine.c
View File

@ -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);