On Tue, Jun 4, 2024 at 6:07 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote:
>
> On Thu, 2023-08-10 at 20:30 +0800, Xuan Zhuo wrote:
> > If the vq is the premapped mode, use the sg_dma_address() directly.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > ---
> > drivers/virtio/virtio_ring.c | 19 +++++++++++++++++--
> > 1 file changed, 17 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c
> > b/drivers/virtio/virtio_ring.c
> > index 8e81b01e0735..f9f772e85a38 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -361,6 +361,11 @@ static struct device *vring_dma_dev(const struct
> > vring_virtqueue *vq)
> > static int vring_map_one_sg(const struct vring_virtqueue *vq, struct
> > scatterlist *sg,
> > enum dma_data_direction direction,
> > dma_addr_t *addr)
> > {
> > + if (vq->premapped) {
> > + *addr = sg_dma_address(sg);
> > + return 0;
> > + }
> > +
>
> I wonder if something needs to be done for KMSAN here, like it's done
> by the next block in this function? I'm looking into what seems to be a
> KMSAN false positive on s390x:
>
> BUG: KMSAN: uninit-value in receive_buf+0x45ca/0x6990
> receive_buf+0x45ca/0x6990
> virtnet_poll+0x17e0/0x3130
> net_rx_action+0x832/0x26e0
> handle_softirqs+0x330/0x10f0
> [...]
I think there's a similar problem on x86 as well:
https://syzkaller.appspot.com/bug?extid=c5336dcd1b741349d27a
I was going to look closer this week.
