Michael S. Tsirkin
2021-Apr-12 09:00 UTC
[PATCH v6 03/10] vhost-vdpa: protect concurrent access to vhost device iotlb
On Mon, Apr 12, 2021 at 10:29:17AM +0800, Yongji Xie wrote:> On Mon, Apr 12, 2021 at 4:49 AM Michael S. Tsirkin <mst at redhat.com> wrote: > > > > On Sun, Apr 11, 2021 at 01:36:18PM +0800, Yongji Xie wrote: > > > On Sat, Apr 10, 2021 at 12:16 AM Michael S. Tsirkin <mst at redhat.com> wrote: > > > > > > > > On Wed, Mar 31, 2021 at 04:05:12PM +0800, Xie Yongji wrote: > > > > > Use vhost_dev->mutex to protect vhost device iotlb from > > > > > concurrent access. > > > > > > > > > > Fixes: 4c8cf318("vhost: introduce vDPA-based backend") > > > > > Cc: stable at vger.kernel.org > > > > > Signed-off-by: Xie Yongji <xieyongji at bytedance.com> > > > > > Acked-by: Jason Wang <jasowang at redhat.com> > > > > > Reviewed-by: Stefano Garzarella <sgarzare at redhat.com> > > > > > > > > I could not figure out whether there's a bug there now. > > > > If yes when is the concurrent access triggered? > > > > > > > > > > When userspace sends the VHOST_IOTLB_MSG_V2 message concurrently? > > > > > > vhost_vdpa_chr_write_iter -> vhost_chr_write_iter -> > > > vhost_vdpa_process_iotlb_msg() > > > > > > Thanks, > > > Yongji > > > > And then what happens currently? > > > > Then we might access vhost_vdpa_map() concurrently and cause > corruption of the list and interval tree in struct vhost_iotlb. > > Thanks, > YongjiOK. Sounds like it's actually needed in this release if possible. Pls add this info in the commit log and post it as a separate patch. -- MST