* Re: [PATCH v1 1/1] virtio: Restore semantics of vq->broken in virtqueues
[not found] <20220630093651.25981-1-alexander.atanasov@virtuozzo.com>
@ 2022-06-30 9:46 ` Michael S. Tsirkin
[not found] ` <1c72645a-f162-2649-bdb6-a28ba93bccd2@virtuozzo.com>
0 siblings, 1 reply; 5+ messages in thread
From: Michael S. Tsirkin @ 2022-06-30 9:46 UTC (permalink / raw)
To: Alexander Atanasov
Cc: linux-s390, Paul E. McKenney, Peter Zijlstra, Marc Zyngier,
Cornelia Huck, Peter Oberparleiter, virtualization, Halil Pasic,
kernel, Vineeth Vijayan, Thomas Gleixner, linux-kernel
On Thu, Jun 30, 2022 at 09:36:46AM +0000, Alexander Atanasov wrote:
> virtio: harden vring IRQ (8b4ec69d7e09) changed the use
> of vq->broken. As result vring_interrupt handles IRQs for
> broken drivers as IRQ_NONE and not IRQ_HANDLED and made impossible
> to initiallize vqs before the driver is ready, i.e. in probe method.
> Balloon driver does this and it can not load because it fails in
> vqs_init with -EIO.
>
> So instead of changing the original intent ot the flag introduce
> a new flag vq->ready which servers the purpose to check of early IRQs
> and restore the behaviour of the vq->broken flag.
>
> Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
Does
commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
Author: Jason Wang <jasowang@redhat.com>
Date: Wed Jun 22 09:29:40 2022 +0800
virtio: disable notification hardening by default
solve the problem for you?
> ---
> drivers/virtio/virtio_ring.c | 20 ++++++++++++++------
> include/linux/virtio.h | 2 +-
> include/linux/virtio_config.h | 10 +++++-----
> 3 files changed, 20 insertions(+), 12 deletions(-)
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: "Paul E. McKenney" <paulmck@kernel.org>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Halil Pasic <pasic@linux.ibm.com>
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: Vineeth Vijayan <vneethv@linux.ibm.com>
> Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
> Cc: linux-s390@vger.kernel.org
> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
>
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 13a7348cedff..dca3cc774584 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -100,6 +100,9 @@ struct vring_virtqueue {
> /* Other side has made a mess, don't try any more. */
> bool broken;
>
> + /* the queue is ready to handle interrupts */
> + bool ready;
> +
> /* Host supports indirect buffers */
> bool indirect;
>
> @@ -1688,7 +1691,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
> vq->we_own_ring = true;
> vq->notify = notify;
> vq->weak_barriers = weak_barriers;
> - vq->broken = true;
> + vq->broken = false;
> + vq->ready = false;
> vq->last_used_idx = 0;
> vq->event_triggered = false;
> vq->num_added = 0;
> @@ -2134,7 +2138,10 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
> return IRQ_NONE;
> }
>
> - if (unlikely(vq->broken)) {
> + if (unlikely(vq->broken))
> + return IRQ_HANDLED;
> +
> + if (unlikely(!vq->ready)) {
> dev_warn_once(&vq->vq.vdev->dev,
> "virtio vring IRQ raised before DRIVER_OK");
> return IRQ_NONE;
> @@ -2180,7 +2187,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
> vq->we_own_ring = false;
> vq->notify = notify;
> vq->weak_barriers = weak_barriers;
> - vq->broken = true;
> + vq->broken = false;
> + vq->ready = false;
> vq->last_used_idx = 0;
> vq->event_triggered = false;
> vq->num_added = 0;
> @@ -2405,7 +2413,7 @@ EXPORT_SYMBOL_GPL(virtio_break_device);
> * (probing and restoring). This function should only be called by the
> * core, not directly by the driver.
> */
> -void __virtio_unbreak_device(struct virtio_device *dev)
> +void __virtio_device_ready(struct virtio_device *dev)
> {
> struct virtqueue *_vq;
>
> @@ -2414,11 +2422,11 @@ void __virtio_unbreak_device(struct virtio_device *dev)
> struct vring_virtqueue *vq = to_vvq(_vq);
>
> /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> - WRITE_ONCE(vq->broken, false);
> + WRITE_ONCE(vq->ready, true);
> }
> spin_unlock(&dev->vqs_list_lock);
> }
> -EXPORT_SYMBOL_GPL(__virtio_unbreak_device);
> +EXPORT_SYMBOL_GPL(__virtio_device_ready);
>
> dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> {
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index d8fdf170637c..538c5959949a 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -131,7 +131,7 @@ void unregister_virtio_device(struct virtio_device *dev);
> bool is_virtio_device(struct device *dev);
>
> void virtio_break_device(struct virtio_device *dev);
> -void __virtio_unbreak_device(struct virtio_device *dev);
> +void __virtio_device_ready(struct virtio_device *dev);
>
> void virtio_config_changed(struct virtio_device *dev);
> #ifdef CONFIG_PM_SLEEP
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 49c7c32815f1..35cf1b26e05a 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -259,21 +259,21 @@ void virtio_device_ready(struct virtio_device *dev)
>
> /*
> * The virtio_synchronize_cbs() makes sure vring_interrupt()
> - * will see the driver specific setup if it sees vq->broken
> + * will see the driver specific setup if it sees vq->ready
> * as false (even if the notifications come before DRIVER_OK).
> */
> virtio_synchronize_cbs(dev);
> - __virtio_unbreak_device(dev);
> + __virtio_device_ready(dev);
> /*
> - * The transport should ensure the visibility of vq->broken
> + * The transport should ensure the visibility of vq->ready
> * before setting DRIVER_OK. See the comments for the transport
> * specific set_status() method.
> *
> * A well behaved device will only notify a virtqueue after
> * DRIVER_OK, this means the device should "see" the coherenct
> - * memory write that set vq->broken as false which is done by
> + * memory write that set vq->ready as true which is done by
> * the driver when it sees DRIVER_OK, then the following
> - * driver's vring_interrupt() will see vq->broken as false so
> + * driver's vring_interrupt() will see vq->true as true so
> * we won't lose any notification.
> */
> dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
> --
> 2.25.1
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v1 1/1] virtio: Restore semantics of vq->broken in virtqueues
[not found] ` <1c72645a-f162-2649-bdb6-a28ba93bccd2@virtuozzo.com>
@ 2022-06-30 15:43 ` Michael S. Tsirkin
2022-07-01 1:12 ` Jason Wang
2022-07-01 1:07 ` Jason Wang
1 sibling, 1 reply; 5+ messages in thread
From: Michael S. Tsirkin @ 2022-06-30 15:43 UTC (permalink / raw)
To: Alexander Atanasov
Cc: linux-s390, Paul E. McKenney, Peter Zijlstra, Marc Zyngier,
Cornelia Huck, Peter Oberparleiter, virtualization, Halil Pasic,
kernel, Vineeth Vijayan, Thomas Gleixner, linux-kernel
On Thu, Jun 30, 2022 at 01:08:53PM +0300, Alexander Atanasov wrote:
> Hello,
>
> On 30/06/2022 12:46, Michael S. Tsirkin wrote:
> > On Thu, Jun 30, 2022 at 09:36:46AM +0000, Alexander Atanasov wrote:
> > > virtio: harden vring IRQ (8b4ec69d7e09) changed the use
> > > of vq->broken. As result vring_interrupt handles IRQs for
> > > broken drivers as IRQ_NONE and not IRQ_HANDLED and made impossible
> > > to initiallize vqs before the driver is ready, i.e. in probe method.
> > > Balloon driver does this and it can not load because it fails in
> > > vqs_init with -EIO.
> > >
> > > So instead of changing the original intent ot the flag introduce
> > > a new flag vq->ready which servers the purpose to check of early IRQs
> > > and restore the behaviour of the vq->broken flag.
> > >
> > > Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
> >
> > Does
> >
> > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > Author: Jason Wang <jasowang@redhat.com>
> > Date: Wed Jun 22 09:29:40 2022 +0800
> >
> > virtio: disable notification hardening by default
> >
> >
> > solve the problem for you?
>
>
> No, it won't if CONFIG_VIRTIO_HARDEN_NOTIFICATION is enabled - balloon still
> won't be able to init vqs.
Yea I intend to make CONFIG_VIRTIO_HARDEN_NOTIFICATION
depend on BROKEN for now.
> The problem is in virtqueue_add_split and virtqueue_add_packed - can not set
> driver_ok without queues.
>
> The return value of the vring_interrupt gets different - and iirc IRQ_NONE
> for broken device can lead to interrupt storms - i am not sure if that is
> valid for virtio devices yet but for real harware most likely.
No, I think it's the reverse. With IRQ_HANDLED an interrupt
storm will keep overloading the CPU since driver tells
kernel all is well. With IRQ_NONE kernel will eventually
intervene and disable the irq.
> Either way if
> you have a mix of drivers working differently depending on return of the
> handler it would get really messy.
>
> RR's original intent was to flag a driver as bad why reuse it like that ?
>
>
> > > drivers/virtio/virtio_ring.c | 20 ++++++++++++++------
> > > include/linux/virtio.h | 2 +-
> > > include/linux/virtio_config.h | 10 +++++-----
> > > 3 files changed, 20 insertions(+), 12 deletions(-)
> > >
> > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > Cc: "Paul E. McKenney" <paulmck@kernel.org>
> > > Cc: Marc Zyngier <maz@kernel.org>
> > > Cc: Halil Pasic <pasic@linux.ibm.com>
> > > Cc: Cornelia Huck <cohuck@redhat.com>
> > > Cc: Vineeth Vijayan <vneethv@linux.ibm.com>
> > > Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
> > > Cc: linux-s390@vger.kernel.org
> > > Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > >
> > >
> > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > > index 13a7348cedff..dca3cc774584 100644
> > > --- a/drivers/virtio/virtio_ring.c
> > > +++ b/drivers/virtio/virtio_ring.c
> > > @@ -100,6 +100,9 @@ struct vring_virtqueue {
> > > /* Other side has made a mess, don't try any more. */
> > > bool broken;
> > > + /* the queue is ready to handle interrupts */
> > > + bool ready;
> > > +
> > > /* Host supports indirect buffers */
> > > bool indirect;
> > > @@ -1688,7 +1691,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
> > > vq->we_own_ring = true;
> > > vq->notify = notify;
> > > vq->weak_barriers = weak_barriers;
> > > - vq->broken = true;
> > > + vq->broken = false;
> > > + vq->ready = false;
> > > vq->last_used_idx = 0;
> > > vq->event_triggered = false;
> > > vq->num_added = 0;
> > > @@ -2134,7 +2138,10 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
> > > return IRQ_NONE;
> > > }
> > > - if (unlikely(vq->broken)) {
> > > + if (unlikely(vq->broken))
> > > + return IRQ_HANDLED;
> > > +
> > > + if (unlikely(!vq->ready)) {
> > > dev_warn_once(&vq->vq.vdev->dev,
> > > "virtio vring IRQ raised before DRIVER_OK");
> > > return IRQ_NONE;
> > > @@ -2180,7 +2187,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
> > > vq->we_own_ring = false;
> > > vq->notify = notify;
> > > vq->weak_barriers = weak_barriers;
> > > - vq->broken = true;
> > > + vq->broken = false;
> > > + vq->ready = false;
> > > vq->last_used_idx = 0;
> > > vq->event_triggered = false;
> > > vq->num_added = 0;
> > > @@ -2405,7 +2413,7 @@ EXPORT_SYMBOL_GPL(virtio_break_device);
> > > * (probing and restoring). This function should only be called by the
> > > * core, not directly by the driver.
> > > */
> > > -void __virtio_unbreak_device(struct virtio_device *dev)
> > > +void __virtio_device_ready(struct virtio_device *dev)
> > > {
> > > struct virtqueue *_vq;
> > > @@ -2414,11 +2422,11 @@ void __virtio_unbreak_device(struct virtio_device *dev)
> > > struct vring_virtqueue *vq = to_vvq(_vq);
> > > /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> > > - WRITE_ONCE(vq->broken, false);
> > > + WRITE_ONCE(vq->ready, true);
> > > }
> > > spin_unlock(&dev->vqs_list_lock);
> > > }
> > > -EXPORT_SYMBOL_GPL(__virtio_unbreak_device);
> > > +EXPORT_SYMBOL_GPL(__virtio_device_ready);
> > > dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> > > {
> > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > > index d8fdf170637c..538c5959949a 100644
> > > --- a/include/linux/virtio.h
> > > +++ b/include/linux/virtio.h
> > > @@ -131,7 +131,7 @@ void unregister_virtio_device(struct virtio_device *dev);
> > > bool is_virtio_device(struct device *dev);
> > > void virtio_break_device(struct virtio_device *dev);
> > > -void __virtio_unbreak_device(struct virtio_device *dev);
> > > +void __virtio_device_ready(struct virtio_device *dev);
> > > void virtio_config_changed(struct virtio_device *dev);
> > > #ifdef CONFIG_PM_SLEEP
> > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> > > index 49c7c32815f1..35cf1b26e05a 100644
> > > --- a/include/linux/virtio_config.h
> > > +++ b/include/linux/virtio_config.h
> > > @@ -259,21 +259,21 @@ void virtio_device_ready(struct virtio_device *dev)
> > > /*
> > > * The virtio_synchronize_cbs() makes sure vring_interrupt()
> > > - * will see the driver specific setup if it sees vq->broken
> > > + * will see the driver specific setup if it sees vq->ready
> > > * as false (even if the notifications come before DRIVER_OK).
> > > */
> > > virtio_synchronize_cbs(dev);
> > > - __virtio_unbreak_device(dev);
> > > + __virtio_device_ready(dev);
> > > /*
> > > - * The transport should ensure the visibility of vq->broken
> > > + * The transport should ensure the visibility of vq->ready
> > > * before setting DRIVER_OK. See the comments for the transport
> > > * specific set_status() method.
> > > *
> > > * A well behaved device will only notify a virtqueue after
> > > * DRIVER_OK, this means the device should "see" the coherenct
> > > - * memory write that set vq->broken as false which is done by
> > > + * memory write that set vq->ready as true which is done by
> > > * the driver when it sees DRIVER_OK, then the following
> > > - * driver's vring_interrupt() will see vq->broken as false so
> > > + * driver's vring_interrupt() will see vq->true as true so
> > > * we won't lose any notification.
> > > */
> > > dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
> > > --
> > > 2.25.1
>
> --
> Regards,
> Alexander Atanasov
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v1 1/1] virtio: Restore semantics of vq->broken in virtqueues
[not found] ` <1c72645a-f162-2649-bdb6-a28ba93bccd2@virtuozzo.com>
2022-06-30 15:43 ` Michael S. Tsirkin
@ 2022-07-01 1:07 ` Jason Wang
1 sibling, 0 replies; 5+ messages in thread
From: Jason Wang @ 2022-07-01 1:07 UTC (permalink / raw)
To: Alexander Atanasov
Cc: linux-s390, Paul E. McKenney, Michael S. Tsirkin, Peter Zijlstra,
Marc Zyngier, Cornelia Huck, Peter Oberparleiter, virtualization,
Halil Pasic, kernel, Vineeth Vijayan, Thomas Gleixner,
linux-kernel
On Thu, Jun 30, 2022 at 6:09 PM Alexander Atanasov
<alexander.atanasov@virtuozzo.com> wrote:
>
> Hello,
>
> On 30/06/2022 12:46, Michael S. Tsirkin wrote:
> > On Thu, Jun 30, 2022 at 09:36:46AM +0000, Alexander Atanasov wrote:
> >> virtio: harden vring IRQ (8b4ec69d7e09) changed the use
> >> of vq->broken. As result vring_interrupt handles IRQs for
> >> broken drivers as IRQ_NONE and not IRQ_HANDLED and made impossible
> >> to initiallize vqs before the driver is ready, i.e. in probe method.
> >> Balloon driver does this and it can not load because it fails in
> >> vqs_init with -EIO.
> >>
> >> So instead of changing the original intent ot the flag introduce
> >> a new flag vq->ready which servers the purpose to check of early IRQs
> >> and restore the behaviour of the vq->broken flag.
> >>
> >> Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
> >
> > Does
> >
> > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > Author: Jason Wang <jasowang@redhat.com>
> > Date: Wed Jun 22 09:29:40 2022 +0800
> >
> > virtio: disable notification hardening by default
> >
> >
> > solve the problem for you?
>
>
> No, it won't if CONFIG_VIRTIO_HARDEN_NOTIFICATION is enabled - balloon
> still won't be able to init vqs.
>
> The problem is in virtqueue_add_split and virtqueue_add_packed - can not
> set driver_ok without queues.
>
> The return value of the vring_interrupt gets different - and iirc
> IRQ_NONE for broken device can lead to interrupt storms - i am not sure
> if that is valid for virtio devices yet but for real harware most
> likely.
Valid but the interrupt will be noted and disabled by the kernel then.
> Either way if you have a mix of drivers working differently
> depending on return of the handler it would get really messy.
Yes, IRQ_HANDLED may break the driver that shares a single IRQ.
>
> RR's original intent was to flag a driver as bad why reuse it like that ?
It's somehow the same, we want to prevent the driver from using the
malicious or buggy device.
Anyhow, I think using a dedicated variable is better.
We are discussing a better approach for hardening the notifications.
But in case, this will be merged:
Acked-by: Jason Wang <jasowang@redhat.com>
Thanks
>
>
> >> drivers/virtio/virtio_ring.c | 20 ++++++++++++++------
> >> include/linux/virtio.h | 2 +-
> >> include/linux/virtio_config.h | 10 +++++-----
> >> 3 files changed, 20 insertions(+), 12 deletions(-)
> >>
> >> Cc: Thomas Gleixner <tglx@linutronix.de>
> >> Cc: Peter Zijlstra <peterz@infradead.org>
> >> Cc: "Paul E. McKenney" <paulmck@kernel.org>
> >> Cc: Marc Zyngier <maz@kernel.org>
> >> Cc: Halil Pasic <pasic@linux.ibm.com>
> >> Cc: Cornelia Huck <cohuck@redhat.com>
> >> Cc: Vineeth Vijayan <vneethv@linux.ibm.com>
> >> Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
> >> Cc: linux-s390@vger.kernel.org
> >> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> >>
> >>
> >> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> >> index 13a7348cedff..dca3cc774584 100644
> >> --- a/drivers/virtio/virtio_ring.c
> >> +++ b/drivers/virtio/virtio_ring.c
> >> @@ -100,6 +100,9 @@ struct vring_virtqueue {
> >> /* Other side has made a mess, don't try any more. */
> >> bool broken;
> >>
> >> + /* the queue is ready to handle interrupts */
> >> + bool ready;
> >> +
> >> /* Host supports indirect buffers */
> >> bool indirect;
> >>
> >> @@ -1688,7 +1691,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
> >> vq->we_own_ring = true;
> >> vq->notify = notify;
> >> vq->weak_barriers = weak_barriers;
> >> - vq->broken = true;
> >> + vq->broken = false;
> >> + vq->ready = false;
> >> vq->last_used_idx = 0;
> >> vq->event_triggered = false;
> >> vq->num_added = 0;
> >> @@ -2134,7 +2138,10 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
> >> return IRQ_NONE;
> >> }
> >>
> >> - if (unlikely(vq->broken)) {
> >> + if (unlikely(vq->broken))
> >> + return IRQ_HANDLED;
> >> +
> >> + if (unlikely(!vq->ready)) {
> >> dev_warn_once(&vq->vq.vdev->dev,
> >> "virtio vring IRQ raised before DRIVER_OK");
> >> return IRQ_NONE;
> >> @@ -2180,7 +2187,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
> >> vq->we_own_ring = false;
> >> vq->notify = notify;
> >> vq->weak_barriers = weak_barriers;
> >> - vq->broken = true;
> >> + vq->broken = false;
> >> + vq->ready = false;
> >> vq->last_used_idx = 0;
> >> vq->event_triggered = false;
> >> vq->num_added = 0;
> >> @@ -2405,7 +2413,7 @@ EXPORT_SYMBOL_GPL(virtio_break_device);
> >> * (probing and restoring). This function should only be called by the
> >> * core, not directly by the driver.
> >> */
> >> -void __virtio_unbreak_device(struct virtio_device *dev)
> >> +void __virtio_device_ready(struct virtio_device *dev)
> >> {
> >> struct virtqueue *_vq;
> >>
> >> @@ -2414,11 +2422,11 @@ void __virtio_unbreak_device(struct virtio_device *dev)
> >> struct vring_virtqueue *vq = to_vvq(_vq);
> >>
> >> /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> >> - WRITE_ONCE(vq->broken, false);
> >> + WRITE_ONCE(vq->ready, true);
> >> }
> >> spin_unlock(&dev->vqs_list_lock);
> >> }
> >> -EXPORT_SYMBOL_GPL(__virtio_unbreak_device);
> >> +EXPORT_SYMBOL_GPL(__virtio_device_ready);
> >>
> >> dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> >> {
> >> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> >> index d8fdf170637c..538c5959949a 100644
> >> --- a/include/linux/virtio.h
> >> +++ b/include/linux/virtio.h
> >> @@ -131,7 +131,7 @@ void unregister_virtio_device(struct virtio_device *dev);
> >> bool is_virtio_device(struct device *dev);
> >>
> >> void virtio_break_device(struct virtio_device *dev);
> >> -void __virtio_unbreak_device(struct virtio_device *dev);
> >> +void __virtio_device_ready(struct virtio_device *dev);
> >>
> >> void virtio_config_changed(struct virtio_device *dev);
> >> #ifdef CONFIG_PM_SLEEP
> >> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> >> index 49c7c32815f1..35cf1b26e05a 100644
> >> --- a/include/linux/virtio_config.h
> >> +++ b/include/linux/virtio_config.h
> >> @@ -259,21 +259,21 @@ void virtio_device_ready(struct virtio_device *dev)
> >>
> >> /*
> >> * The virtio_synchronize_cbs() makes sure vring_interrupt()
> >> - * will see the driver specific setup if it sees vq->broken
> >> + * will see the driver specific setup if it sees vq->ready
> >> * as false (even if the notifications come before DRIVER_OK).
> >> */
> >> virtio_synchronize_cbs(dev);
> >> - __virtio_unbreak_device(dev);
> >> + __virtio_device_ready(dev);
> >> /*
> >> - * The transport should ensure the visibility of vq->broken
> >> + * The transport should ensure the visibility of vq->ready
> >> * before setting DRIVER_OK. See the comments for the transport
> >> * specific set_status() method.
> >> *
> >> * A well behaved device will only notify a virtqueue after
> >> * DRIVER_OK, this means the device should "see" the coherenct
> >> - * memory write that set vq->broken as false which is done by
> >> + * memory write that set vq->ready as true which is done by
> >> * the driver when it sees DRIVER_OK, then the following
> >> - * driver's vring_interrupt() will see vq->broken as false so
> >> + * driver's vring_interrupt() will see vq->true as true so
> >> * we won't lose any notification.
> >> */
> >> dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
> >> --
> >> 2.25.1
>
> --
> Regards,
> Alexander Atanasov
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v1 1/1] virtio: Restore semantics of vq->broken in virtqueues
2022-06-30 15:43 ` Michael S. Tsirkin
@ 2022-07-01 1:12 ` Jason Wang
2022-07-01 6:14 ` Michael S. Tsirkin
0 siblings, 1 reply; 5+ messages in thread
From: Jason Wang @ 2022-07-01 1:12 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: linux-s390, Paul E. McKenney, Peter Zijlstra, Marc Zyngier,
Cornelia Huck, Alexander Atanasov, Peter Oberparleiter,
virtualization, Halil Pasic, kernel, Vineeth Vijayan,
Thomas Gleixner, linux-kernel
On Thu, Jun 30, 2022 at 11:44 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Thu, Jun 30, 2022 at 01:08:53PM +0300, Alexander Atanasov wrote:
> > Hello,
> >
> > On 30/06/2022 12:46, Michael S. Tsirkin wrote:
> > > On Thu, Jun 30, 2022 at 09:36:46AM +0000, Alexander Atanasov wrote:
> > > > virtio: harden vring IRQ (8b4ec69d7e09) changed the use
> > > > of vq->broken. As result vring_interrupt handles IRQs for
> > > > broken drivers as IRQ_NONE and not IRQ_HANDLED and made impossible
> > > > to initiallize vqs before the driver is ready, i.e. in probe method.
> > > > Balloon driver does this and it can not load because it fails in
> > > > vqs_init with -EIO.
> > > >
> > > > So instead of changing the original intent ot the flag introduce
> > > > a new flag vq->ready which servers the purpose to check of early IRQs
> > > > and restore the behaviour of the vq->broken flag.
> > > >
> > > > Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
> > >
> > > Does
> > >
> > > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > > Author: Jason Wang <jasowang@redhat.com>
> > > Date: Wed Jun 22 09:29:40 2022 +0800
> > >
> > > virtio: disable notification hardening by default
> > >
> > >
> > > solve the problem for you?
> >
> >
> > No, it won't if CONFIG_VIRTIO_HARDEN_NOTIFICATION is enabled - balloon still
> > won't be able to init vqs.
>
> Yea I intend to make CONFIG_VIRTIO_HARDEN_NOTIFICATION
> depend on BROKEN for now.
>
> > The problem is in virtqueue_add_split and virtqueue_add_packed - can not set
> > driver_ok without queues.
> >
> > The return value of the vring_interrupt gets different - and iirc IRQ_NONE
> > for broken device can lead to interrupt storms - i am not sure if that is
> > valid for virtio devices yet but for real harware most likely.
>
> No, I think it's the reverse. With IRQ_HANDLED an interrupt
> storm will keep overloading the CPU since driver tells
> kernel all is well. With IRQ_NONE kernel will eventually
> intervene and disable the irq.
Yes, and users may get a warn.
For IRQ_HANDLED, it has an issue when the driver is sharing IRQ with
other drivers.
Thanks
>
> > Either way if
> > you have a mix of drivers working differently depending on return of the
> > handler it would get really messy.
> >
> > RR's original intent was to flag a driver as bad why reuse it like that ?
> >
> >
> > > > drivers/virtio/virtio_ring.c | 20 ++++++++++++++------
> > > > include/linux/virtio.h | 2 +-
> > > > include/linux/virtio_config.h | 10 +++++-----
> > > > 3 files changed, 20 insertions(+), 12 deletions(-)
> > > >
> > > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > > Cc: "Paul E. McKenney" <paulmck@kernel.org>
> > > > Cc: Marc Zyngier <maz@kernel.org>
> > > > Cc: Halil Pasic <pasic@linux.ibm.com>
> > > > Cc: Cornelia Huck <cohuck@redhat.com>
> > > > Cc: Vineeth Vijayan <vneethv@linux.ibm.com>
> > > > Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
> > > > Cc: linux-s390@vger.kernel.org
> > > > Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > >
> > > >
> > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > > > index 13a7348cedff..dca3cc774584 100644
> > > > --- a/drivers/virtio/virtio_ring.c
> > > > +++ b/drivers/virtio/virtio_ring.c
> > > > @@ -100,6 +100,9 @@ struct vring_virtqueue {
> > > > /* Other side has made a mess, don't try any more. */
> > > > bool broken;
> > > > + /* the queue is ready to handle interrupts */
> > > > + bool ready;
> > > > +
> > > > /* Host supports indirect buffers */
> > > > bool indirect;
> > > > @@ -1688,7 +1691,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
> > > > vq->we_own_ring = true;
> > > > vq->notify = notify;
> > > > vq->weak_barriers = weak_barriers;
> > > > - vq->broken = true;
> > > > + vq->broken = false;
> > > > + vq->ready = false;
> > > > vq->last_used_idx = 0;
> > > > vq->event_triggered = false;
> > > > vq->num_added = 0;
> > > > @@ -2134,7 +2138,10 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
> > > > return IRQ_NONE;
> > > > }
> > > > - if (unlikely(vq->broken)) {
> > > > + if (unlikely(vq->broken))
> > > > + return IRQ_HANDLED;
> > > > +
> > > > + if (unlikely(!vq->ready)) {
> > > > dev_warn_once(&vq->vq.vdev->dev,
> > > > "virtio vring IRQ raised before DRIVER_OK");
> > > > return IRQ_NONE;
> > > > @@ -2180,7 +2187,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
> > > > vq->we_own_ring = false;
> > > > vq->notify = notify;
> > > > vq->weak_barriers = weak_barriers;
> > > > - vq->broken = true;
> > > > + vq->broken = false;
> > > > + vq->ready = false;
> > > > vq->last_used_idx = 0;
> > > > vq->event_triggered = false;
> > > > vq->num_added = 0;
> > > > @@ -2405,7 +2413,7 @@ EXPORT_SYMBOL_GPL(virtio_break_device);
> > > > * (probing and restoring). This function should only be called by the
> > > > * core, not directly by the driver.
> > > > */
> > > > -void __virtio_unbreak_device(struct virtio_device *dev)
> > > > +void __virtio_device_ready(struct virtio_device *dev)
> > > > {
> > > > struct virtqueue *_vq;
> > > > @@ -2414,11 +2422,11 @@ void __virtio_unbreak_device(struct virtio_device *dev)
> > > > struct vring_virtqueue *vq = to_vvq(_vq);
> > > > /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> > > > - WRITE_ONCE(vq->broken, false);
> > > > + WRITE_ONCE(vq->ready, true);
> > > > }
> > > > spin_unlock(&dev->vqs_list_lock);
> > > > }
> > > > -EXPORT_SYMBOL_GPL(__virtio_unbreak_device);
> > > > +EXPORT_SYMBOL_GPL(__virtio_device_ready);
> > > > dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> > > > {
> > > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > > > index d8fdf170637c..538c5959949a 100644
> > > > --- a/include/linux/virtio.h
> > > > +++ b/include/linux/virtio.h
> > > > @@ -131,7 +131,7 @@ void unregister_virtio_device(struct virtio_device *dev);
> > > > bool is_virtio_device(struct device *dev);
> > > > void virtio_break_device(struct virtio_device *dev);
> > > > -void __virtio_unbreak_device(struct virtio_device *dev);
> > > > +void __virtio_device_ready(struct virtio_device *dev);
> > > > void virtio_config_changed(struct virtio_device *dev);
> > > > #ifdef CONFIG_PM_SLEEP
> > > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> > > > index 49c7c32815f1..35cf1b26e05a 100644
> > > > --- a/include/linux/virtio_config.h
> > > > +++ b/include/linux/virtio_config.h
> > > > @@ -259,21 +259,21 @@ void virtio_device_ready(struct virtio_device *dev)
> > > > /*
> > > > * The virtio_synchronize_cbs() makes sure vring_interrupt()
> > > > - * will see the driver specific setup if it sees vq->broken
> > > > + * will see the driver specific setup if it sees vq->ready
> > > > * as false (even if the notifications come before DRIVER_OK).
> > > > */
> > > > virtio_synchronize_cbs(dev);
> > > > - __virtio_unbreak_device(dev);
> > > > + __virtio_device_ready(dev);
> > > > /*
> > > > - * The transport should ensure the visibility of vq->broken
> > > > + * The transport should ensure the visibility of vq->ready
> > > > * before setting DRIVER_OK. See the comments for the transport
> > > > * specific set_status() method.
> > > > *
> > > > * A well behaved device will only notify a virtqueue after
> > > > * DRIVER_OK, this means the device should "see" the coherenct
> > > > - * memory write that set vq->broken as false which is done by
> > > > + * memory write that set vq->ready as true which is done by
> > > > * the driver when it sees DRIVER_OK, then the following
> > > > - * driver's vring_interrupt() will see vq->broken as false so
> > > > + * driver's vring_interrupt() will see vq->true as true so
> > > > * we won't lose any notification.
> > > > */
> > > > dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
> > > > --
> > > > 2.25.1
> >
> > --
> > Regards,
> > Alexander Atanasov
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v1 1/1] virtio: Restore semantics of vq->broken in virtqueues
2022-07-01 1:12 ` Jason Wang
@ 2022-07-01 6:14 ` Michael S. Tsirkin
0 siblings, 0 replies; 5+ messages in thread
From: Michael S. Tsirkin @ 2022-07-01 6:14 UTC (permalink / raw)
To: Jason Wang
Cc: linux-s390, Paul E. McKenney, Peter Zijlstra, Marc Zyngier,
Cornelia Huck, Alexander Atanasov, Peter Oberparleiter,
virtualization, Halil Pasic, kernel, Vineeth Vijayan,
Thomas Gleixner, linux-kernel
On Fri, Jul 01, 2022 at 09:12:58AM +0800, Jason Wang wrote:
> On Thu, Jun 30, 2022 at 11:44 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Thu, Jun 30, 2022 at 01:08:53PM +0300, Alexander Atanasov wrote:
> > > Hello,
> > >
> > > On 30/06/2022 12:46, Michael S. Tsirkin wrote:
> > > > On Thu, Jun 30, 2022 at 09:36:46AM +0000, Alexander Atanasov wrote:
> > > > > virtio: harden vring IRQ (8b4ec69d7e09) changed the use
> > > > > of vq->broken. As result vring_interrupt handles IRQs for
> > > > > broken drivers as IRQ_NONE and not IRQ_HANDLED and made impossible
> > > > > to initiallize vqs before the driver is ready, i.e. in probe method.
> > > > > Balloon driver does this and it can not load because it fails in
> > > > > vqs_init with -EIO.
> > > > >
> > > > > So instead of changing the original intent ot the flag introduce
> > > > > a new flag vq->ready which servers the purpose to check of early IRQs
> > > > > and restore the behaviour of the vq->broken flag.
> > > > >
> > > > > Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
> > > >
> > > > Does
> > > >
> > > > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > > > Author: Jason Wang <jasowang@redhat.com>
> > > > Date: Wed Jun 22 09:29:40 2022 +0800
> > > >
> > > > virtio: disable notification hardening by default
> > > >
> > > >
> > > > solve the problem for you?
> > >
> > >
> > > No, it won't if CONFIG_VIRTIO_HARDEN_NOTIFICATION is enabled - balloon still
> > > won't be able to init vqs.
> >
> > Yea I intend to make CONFIG_VIRTIO_HARDEN_NOTIFICATION
> > depend on BROKEN for now.
> >
> > > The problem is in virtqueue_add_split and virtqueue_add_packed - can not set
> > > driver_ok without queues.
> > >
> > > The return value of the vring_interrupt gets different - and iirc IRQ_NONE
> > > for broken device can lead to interrupt storms - i am not sure if that is
> > > valid for virtio devices yet but for real harware most likely.
> >
> > No, I think it's the reverse. With IRQ_HANDLED an interrupt
> > storm will keep overloading the CPU since driver tells
> > kernel all is well. With IRQ_NONE kernel will eventually
> > intervene and disable the irq.
>
> Yes, and users may get a warn.
>
> For IRQ_HANDLED, it has an issue when the driver is sharing IRQ with
> other drivers.
>
> Thanks
Couldn't tell whether you are agreeing or disagreeing with me here.
> >
> > > Either way if
> > > you have a mix of drivers working differently depending on return of the
> > > handler it would get really messy.
> > >
> > > RR's original intent was to flag a driver as bad why reuse it like that ?
> > >
> > >
> > > > > drivers/virtio/virtio_ring.c | 20 ++++++++++++++------
> > > > > include/linux/virtio.h | 2 +-
> > > > > include/linux/virtio_config.h | 10 +++++-----
> > > > > 3 files changed, 20 insertions(+), 12 deletions(-)
> > > > >
> > > > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > > > Cc: "Paul E. McKenney" <paulmck@kernel.org>
> > > > > Cc: Marc Zyngier <maz@kernel.org>
> > > > > Cc: Halil Pasic <pasic@linux.ibm.com>
> > > > > Cc: Cornelia Huck <cohuck@redhat.com>
> > > > > Cc: Vineeth Vijayan <vneethv@linux.ibm.com>
> > > > > Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
> > > > > Cc: linux-s390@vger.kernel.org
> > > > > Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > > >
> > > > >
> > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > > > > index 13a7348cedff..dca3cc774584 100644
> > > > > --- a/drivers/virtio/virtio_ring.c
> > > > > +++ b/drivers/virtio/virtio_ring.c
> > > > > @@ -100,6 +100,9 @@ struct vring_virtqueue {
> > > > > /* Other side has made a mess, don't try any more. */
> > > > > bool broken;
> > > > > + /* the queue is ready to handle interrupts */
> > > > > + bool ready;
> > > > > +
> > > > > /* Host supports indirect buffers */
> > > > > bool indirect;
> > > > > @@ -1688,7 +1691,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
> > > > > vq->we_own_ring = true;
> > > > > vq->notify = notify;
> > > > > vq->weak_barriers = weak_barriers;
> > > > > - vq->broken = true;
> > > > > + vq->broken = false;
> > > > > + vq->ready = false;
> > > > > vq->last_used_idx = 0;
> > > > > vq->event_triggered = false;
> > > > > vq->num_added = 0;
> > > > > @@ -2134,7 +2138,10 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
> > > > > return IRQ_NONE;
> > > > > }
> > > > > - if (unlikely(vq->broken)) {
> > > > > + if (unlikely(vq->broken))
> > > > > + return IRQ_HANDLED;
> > > > > +
> > > > > + if (unlikely(!vq->ready)) {
> > > > > dev_warn_once(&vq->vq.vdev->dev,
> > > > > "virtio vring IRQ raised before DRIVER_OK");
> > > > > return IRQ_NONE;
> > > > > @@ -2180,7 +2187,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
> > > > > vq->we_own_ring = false;
> > > > > vq->notify = notify;
> > > > > vq->weak_barriers = weak_barriers;
> > > > > - vq->broken = true;
> > > > > + vq->broken = false;
> > > > > + vq->ready = false;
> > > > > vq->last_used_idx = 0;
> > > > > vq->event_triggered = false;
> > > > > vq->num_added = 0;
> > > > > @@ -2405,7 +2413,7 @@ EXPORT_SYMBOL_GPL(virtio_break_device);
> > > > > * (probing and restoring). This function should only be called by the
> > > > > * core, not directly by the driver.
> > > > > */
> > > > > -void __virtio_unbreak_device(struct virtio_device *dev)
> > > > > +void __virtio_device_ready(struct virtio_device *dev)
> > > > > {
> > > > > struct virtqueue *_vq;
> > > > > @@ -2414,11 +2422,11 @@ void __virtio_unbreak_device(struct virtio_device *dev)
> > > > > struct vring_virtqueue *vq = to_vvq(_vq);
> > > > > /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> > > > > - WRITE_ONCE(vq->broken, false);
> > > > > + WRITE_ONCE(vq->ready, true);
> > > > > }
> > > > > spin_unlock(&dev->vqs_list_lock);
> > > > > }
> > > > > -EXPORT_SYMBOL_GPL(__virtio_unbreak_device);
> > > > > +EXPORT_SYMBOL_GPL(__virtio_device_ready);
> > > > > dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
> > > > > {
> > > > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > > > > index d8fdf170637c..538c5959949a 100644
> > > > > --- a/include/linux/virtio.h
> > > > > +++ b/include/linux/virtio.h
> > > > > @@ -131,7 +131,7 @@ void unregister_virtio_device(struct virtio_device *dev);
> > > > > bool is_virtio_device(struct device *dev);
> > > > > void virtio_break_device(struct virtio_device *dev);
> > > > > -void __virtio_unbreak_device(struct virtio_device *dev);
> > > > > +void __virtio_device_ready(struct virtio_device *dev);
> > > > > void virtio_config_changed(struct virtio_device *dev);
> > > > > #ifdef CONFIG_PM_SLEEP
> > > > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> > > > > index 49c7c32815f1..35cf1b26e05a 100644
> > > > > --- a/include/linux/virtio_config.h
> > > > > +++ b/include/linux/virtio_config.h
> > > > > @@ -259,21 +259,21 @@ void virtio_device_ready(struct virtio_device *dev)
> > > > > /*
> > > > > * The virtio_synchronize_cbs() makes sure vring_interrupt()
> > > > > - * will see the driver specific setup if it sees vq->broken
> > > > > + * will see the driver specific setup if it sees vq->ready
> > > > > * as false (even if the notifications come before DRIVER_OK).
> > > > > */
> > > > > virtio_synchronize_cbs(dev);
> > > > > - __virtio_unbreak_device(dev);
> > > > > + __virtio_device_ready(dev);
> > > > > /*
> > > > > - * The transport should ensure the visibility of vq->broken
> > > > > + * The transport should ensure the visibility of vq->ready
> > > > > * before setting DRIVER_OK. See the comments for the transport
> > > > > * specific set_status() method.
> > > > > *
> > > > > * A well behaved device will only notify a virtqueue after
> > > > > * DRIVER_OK, this means the device should "see" the coherenct
> > > > > - * memory write that set vq->broken as false which is done by
> > > > > + * memory write that set vq->ready as true which is done by
> > > > > * the driver when it sees DRIVER_OK, then the following
> > > > > - * driver's vring_interrupt() will see vq->broken as false so
> > > > > + * driver's vring_interrupt() will see vq->true as true so
> > > > > * we won't lose any notification.
> > > > > */
> > > > > dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
> > > > > --
> > > > > 2.25.1
> > >
> > > --
> > > Regards,
> > > Alexander Atanasov
> >
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-06-30 9:46 ` [PATCH v1 1/1] virtio: Restore semantics of vq->broken in virtqueues Michael S. Tsirkin
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2022-07-01 1:07 ` Jason Wang
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for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).