Michael S. Tsirkin
2014-Oct-20 13:35 UTC
[PATCH v4 13/25] virtio_console: enable VQs early
On Mon, Oct 20, 2014 at 02:42:23PM +0200, Cornelia Huck wrote:> On Mon, 20 Oct 2014 13:07:50 +0100 > Thomas Graf <tgraf at suug.ch> wrote: > > > On 10/13/14 at 10:50am, Michael S. Tsirkin wrote: > > > virtio spec requires drivers to set DRIVER_OK before using VQs. > > > This is set automatically after probe returns, virtio console violated this > > > rule by adding inbufs, which causes the VQ to be used directly within > > > probe. > > > > > > To fix, call virtio_device_ready before using VQs. > > > > > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > > > --- > > > drivers/char/virtio_console.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > > > index b585b47..6ebe8f6 100644 > > > --- a/drivers/char/virtio_console.c > > > +++ b/drivers/char/virtio_console.c > > > @@ -1449,6 +1449,8 @@ static int add_port(struct ports_device *portdev, u32 id) > > > spin_lock_init(&port->outvq_lock); > > > init_waitqueue_head(&port->waitqueue); > > > > > > + virtio_device_ready(portdev->vdev); > > > + > > > /* Fill the in_vq with buffers so the host can send us data. */ > > > nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); > > > if (!nr_added_bufs) { > > > > Seems like probe and add_port() now both set VIRTIO_CONFIG_S_DRIVER_OK > > I think we need to set this in the probe function instead, otherwise we > fail for multiqueue (which also wants to use the control queue early). > > Completely untested patch below; I can send this with proper s-o-b if > it helps. > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index bfa6400..cf7a561 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -1449,8 +1449,6 @@ static int add_port(struct ports_device *portdev, u32 id) > spin_lock_init(&port->outvq_lock); > init_waitqueue_head(&port->waitqueue); > > - virtio_device_ready(portdev->vdev); > - > /* Fill the in_vq with buffers so the host can send us data. */ > nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); > if (!nr_added_bufs) { > @@ -2026,6 +2024,8 @@ static int virtcons_probe(struct virtio_device *vdev) > spin_lock_init(&portdev->ports_lock); > INIT_LIST_HEAD(&portdev->ports); > > + virtio_device_ready(portdev->vdev); > + > if (multiport) { > unsigned int nr_added_bufs; >I wanted to set DRIVER_OK as late as possible, to both reduce the chance it can fail after DRIVER_OK and to reduce the risk of introducing a regression since old qemu might only start sending interrupts after DRIVER_OK is set. So I wanted everything completely initialized before DRIVER_OK. You patch makes sense to me since nothing can fail, and we won't get interrupts before we add inbufs. Reviewed-by: Michael S. Tsirkin <mst at redhat.com> Testig will report shortly, pls send with sob line. -- MST
Commit f5866db6 (virtio_console: enable VQs early) tried to make
sure that DRIVER_OK was set when virtio_console started using its
virtqueues. Doing this in add_port(), however, means that we try
to set DRIVER_OK again when when a port is dynamically added after
the probe function is done.
Let's move virtio_device_ready() to the probe function just before
trying to use the virtqueues instead. This is fine as nothing can
fail inbetween.
Reported-by: Thomas Graf <tgraf at suug.ch>
Reviewed-by: Michael S. Tsirkin <mst at redhat.com>
Signed-off-by: Cornelia Huck <cornelia.huck at de.ibm.com>
---
drivers/char/virtio_console.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index bfa6400..cf7a561 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1449,8 +1449,6 @@ static int add_port(struct ports_device *portdev, u32 id)
spin_lock_init(&port->outvq_lock);
init_waitqueue_head(&port->waitqueue);
- virtio_device_ready(portdev->vdev);
-
/* Fill the in_vq with buffers so the host can send us data. */
nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock);
if (!nr_added_bufs) {
@@ -2026,6 +2024,8 @@ static int virtcons_probe(struct virtio_device *vdev)
spin_lock_init(&portdev->ports_lock);
INIT_LIST_HEAD(&portdev->ports);
+ virtio_device_ready(portdev->vdev);
+
if (multiport) {
unsigned int nr_added_bufs;
--
1.8.5.5
Michael S. Tsirkin
2014-Oct-20 14:04 UTC
[PATCH v4 13/25] virtio_console: enable VQs early
On Mon, Oct 20, 2014 at 04:35:55PM +0300, Michael S. Tsirkin wrote:> On Mon, Oct 20, 2014 at 02:42:23PM +0200, Cornelia Huck wrote: > > On Mon, 20 Oct 2014 13:07:50 +0100 > > Thomas Graf <tgraf at suug.ch> wrote: > > > > > On 10/13/14 at 10:50am, Michael S. Tsirkin wrote: > > > > virtio spec requires drivers to set DRIVER_OK before using VQs. > > > > This is set automatically after probe returns, virtio console violated this > > > > rule by adding inbufs, which causes the VQ to be used directly within > > > > probe. > > > > > > > > To fix, call virtio_device_ready before using VQs. > > > > > > > > Signed-off-by: Michael S. Tsirkin <mst at redhat.com> > > > > --- > > > > drivers/char/virtio_console.c | 2 ++ > > > > 1 file changed, 2 insertions(+) > > > > > > > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > > > > index b585b47..6ebe8f6 100644 > > > > --- a/drivers/char/virtio_console.c > > > > +++ b/drivers/char/virtio_console.c > > > > @@ -1449,6 +1449,8 @@ static int add_port(struct ports_device *portdev, u32 id) > > > > spin_lock_init(&port->outvq_lock); > > > > init_waitqueue_head(&port->waitqueue); > > > > > > > > + virtio_device_ready(portdev->vdev); > > > > + > > > > /* Fill the in_vq with buffers so the host can send us data. */ > > > > nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); > > > > if (!nr_added_bufs) { > > > > > > Seems like probe and add_port() now both set VIRTIO_CONFIG_S_DRIVER_OK > > > > I think we need to set this in the probe function instead, otherwise we > > fail for multiqueue (which also wants to use the control queue early). > > > > Completely untested patch below; I can send this with proper s-o-b if > > it helps. > > > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > > index bfa6400..cf7a561 100644 > > --- a/drivers/char/virtio_console.c > > +++ b/drivers/char/virtio_console.c > > @@ -1449,8 +1449,6 @@ static int add_port(struct ports_device *portdev, u32 id) > > spin_lock_init(&port->outvq_lock); > > init_waitqueue_head(&port->waitqueue); > > > > - virtio_device_ready(portdev->vdev); > > - > > /* Fill the in_vq with buffers so the host can send us data. */ > > nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); > > if (!nr_added_bufs) { > > @@ -2026,6 +2024,8 @@ static int virtcons_probe(struct virtio_device *vdev) > > spin_lock_init(&portdev->ports_lock); > > INIT_LIST_HEAD(&portdev->ports); > > > > + virtio_device_ready(portdev->vdev); > > + > > if (multiport) { > > unsigned int nr_added_bufs; > > > > I wanted to set DRIVER_OK as late as possible, to both reduce > the chance it can fail after DRIVER_OK and to reduce the risk of > introducing a regression since old qemu might only start sending > interrupts after DRIVER_OK is set. > > So I wanted everything completely initialized before DRIVER_OK. > > You patch makes sense to me since nothing can fail, > and we won't get interrupts before we add inbufs. > > Reviewed-by: Michael S. Tsirkin <mst at redhat.com> > > Testig will report shortly, pls send with sob line.Sure enough, this helps: Tested-by: Michael S. Tsirkin <mst at redhat.com> Acked-by: Michael S. Tsirkin <mst at redhat.com> Pls repost as a top-level patch.> -- > MST
On Mon, Oct 20, 2014 at 03:58:49PM +0200, Cornelia Huck wrote:> Commit f5866db6 (virtio_console: enable VQs early) tried to make > sure that DRIVER_OK was set when virtio_console started using its > virtqueues. Doing this in add_port(), however, means that we try > to set DRIVER_OK again when when a port is dynamically added after > the probe function is done. > > Let's move virtio_device_ready() to the probe function just before > trying to use the virtqueues instead. This is fine as nothing can > fail inbetween. > > Reported-by: Thomas Graf <tgraf at suug.ch> > Reviewed-by: Michael S. Tsirkin <mst at redhat.com> > Signed-off-by: Cornelia Huck <cornelia.huck at de.ibm.com>Thanks! Acked-by: Michael S. Tsirkin <mst at redhat.com> Tested-by: Michael S. Tsirkin <mst at redhat.com>> --- > drivers/char/virtio_console.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index bfa6400..cf7a561 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -1449,8 +1449,6 @@ static int add_port(struct ports_device *portdev, u32 id) > spin_lock_init(&port->outvq_lock); > init_waitqueue_head(&port->waitqueue); > > - virtio_device_ready(portdev->vdev); > - > /* Fill the in_vq with buffers so the host can send us data. */ > nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); > if (!nr_added_bufs) { > @@ -2026,6 +2024,8 @@ static int virtcons_probe(struct virtio_device *vdev) > spin_lock_init(&portdev->ports_lock); > INIT_LIST_HEAD(&portdev->ports); > > + virtio_device_ready(portdev->vdev); > + > if (multiport) { > unsigned int nr_added_bufs; > > -- > 1.8.5.5
On 10/20/14 at 05:04pm, Michael S. Tsirkin wrote:> Sure enough, this helps: > > Tested-by: Michael S. Tsirkin <mst at redhat.com> > Acked-by: Michael S. Tsirkin <mst at redhat.com> > > Pls repost as a top-level patch.Thanks for fixing this so promptly.