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 <[email protected]>
Does
commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
Author: Jason Wang <[email protected]>
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 <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: "Paul E. McKenney" <[email protected]>
> Cc: Marc Zyngier <[email protected]>
> Cc: Halil Pasic <[email protected]>
> Cc: Cornelia Huck <[email protected]>
> Cc: Vineeth Vijayan <[email protected]>
> Cc: Peter Oberparleiter <[email protected]>
> Cc: [email protected]
> Cc: Xuan Zhuo <[email protected]>
>
>
> 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
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 <[email protected]>
>
> Does
>
> commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> Author: Jason Wang <[email protected]>
> 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. 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 <[email protected]>
>> Cc: Peter Zijlstra <[email protected]>
>> Cc: "Paul E. McKenney" <[email protected]>
>> Cc: Marc Zyngier <[email protected]>
>> Cc: Halil Pasic <[email protected]>
>> Cc: Cornelia Huck <[email protected]>
>> Cc: Vineeth Vijayan <[email protected]>
>> Cc: Peter Oberparleiter <[email protected]>
>> Cc: [email protected]
>> Cc: Xuan Zhuo <[email protected]>
>>
>>
>> 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
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 <[email protected]>
> >
> > Does
> >
> > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > Author: Jason Wang <[email protected]>
> > 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 <[email protected]>
> > > Cc: Peter Zijlstra <[email protected]>
> > > Cc: "Paul E. McKenney" <[email protected]>
> > > Cc: Marc Zyngier <[email protected]>
> > > Cc: Halil Pasic <[email protected]>
> > > Cc: Cornelia Huck <[email protected]>
> > > Cc: Vineeth Vijayan <[email protected]>
> > > Cc: Peter Oberparleiter <[email protected]>
> > > Cc: [email protected]
> > > Cc: Xuan Zhuo <[email protected]>
> > >
> > >
> > > 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
On Thu, Jun 30, 2022 at 6:09 PM Alexander Atanasov
<[email protected]> 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 <[email protected]>
> >
> > Does
> >
> > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > Author: Jason Wang <[email protected]>
> > 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 <[email protected]>
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 <[email protected]>
> >> Cc: Peter Zijlstra <[email protected]>
> >> Cc: "Paul E. McKenney" <[email protected]>
> >> Cc: Marc Zyngier <[email protected]>
> >> Cc: Halil Pasic <[email protected]>
> >> Cc: Cornelia Huck <[email protected]>
> >> Cc: Vineeth Vijayan <[email protected]>
> >> Cc: Peter Oberparleiter <[email protected]>
> >> Cc: [email protected]
> >> Cc: Xuan Zhuo <[email protected]>
> >>
> >>
> >> 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
>
On Thu, Jun 30, 2022 at 11:44 PM Michael S. Tsirkin <[email protected]> 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 <[email protected]>
> > >
> > > Does
> > >
> > > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > > Author: Jason Wang <[email protected]>
> > > 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 <[email protected]>
> > > > Cc: Peter Zijlstra <[email protected]>
> > > > Cc: "Paul E. McKenney" <[email protected]>
> > > > Cc: Marc Zyngier <[email protected]>
> > > > Cc: Halil Pasic <[email protected]>
> > > > Cc: Cornelia Huck <[email protected]>
> > > > Cc: Vineeth Vijayan <[email protected]>
> > > > Cc: Peter Oberparleiter <[email protected]>
> > > > Cc: [email protected]
> > > > Cc: Xuan Zhuo <[email protected]>
> > > >
> > > >
> > > > 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
>
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 <[email protected]> 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 <[email protected]>
> > > >
> > > > Does
> > > >
> > > > commit c346dae4f3fbce51bbd4f2ec5e8c6f9b91e93163
> > > > Author: Jason Wang <[email protected]>
> > > > 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 <[email protected]>
> > > > > Cc: Peter Zijlstra <[email protected]>
> > > > > Cc: "Paul E. McKenney" <[email protected]>
> > > > > Cc: Marc Zyngier <[email protected]>
> > > > > Cc: Halil Pasic <[email protected]>
> > > > > Cc: Cornelia Huck <[email protected]>
> > > > > Cc: Vineeth Vijayan <[email protected]>
> > > > > Cc: Peter Oberparleiter <[email protected]>
> > > > > Cc: [email protected]
> > > > > Cc: Xuan Zhuo <[email protected]>
> > > > >
> > > > >
> > > > > 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
> >
virtio: harden vring IRQ (8b4ec69d7e09) changed the meaning
of vq->broken which results in 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.
Acked-by: Jason Wang <[email protected]>
Signed-off-by: Alexander Atanasov <[email protected]>
---
drivers/virtio/virtio_ring.c | 33 ++++++++++++++++++---------------
include/linux/virtio.h | 4 +++-
include/linux/virtio_config.h | 12 ++++++------
3 files changed, 27 insertions(+), 22 deletions(-)
V1->V2:
Reworked on top of config option to disable the hardening.
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 643ca779fcc6..f0e645e17848 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;
@@ -1708,10 +1711,9 @@ static struct virtqueue *vring_create_virtqueue_packed(
vq->we_own_ring = true;
vq->notify = notify;
vq->weak_barriers = weak_barriers;
-#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
- vq->broken = true;
-#else
vq->broken = false;
+#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+ vq->ready = false;
#endif
vq->last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR);
vq->event_triggered = false;
@@ -2157,15 +2159,16 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
return IRQ_NONE;
}
- if (unlikely(vq->broken)) {
+ if (unlikely(vq->broken))
+ return IRQ_HANDLED;
+
#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+ if (unlikely(!vq->ready)) {
dev_warn_once(&vq->vq.vdev->dev,
"virtio vring IRQ raised before DRIVER_OK");
return IRQ_NONE;
-#else
- return IRQ_HANDLED;
-#endif
}
+#endif
/* Just a hint for performance: so it's ok that this can be racy! */
if (vq->event)
@@ -2207,10 +2210,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
vq->we_own_ring = false;
vq->notify = notify;
vq->weak_barriers = weak_barriers;
-#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
- vq->broken = true;
-#else
vq->broken = false;
+#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+ vq->ready = false;
#endif
vq->last_used_idx = 0;
vq->event_triggered = false;
@@ -2429,14 +2431,15 @@ void virtio_break_device(struct virtio_device *dev)
}
EXPORT_SYMBOL_GPL(virtio_break_device);
+#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
/*
* This should allow the device to be used by the driver. You may
* need to grab appropriate locks to flush the write to
- * vq->broken. This should only be used in some specific case e.g
+ * vq->ready. This should only be used in some specific case e.g
* (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;
@@ -2444,12 +2447,12 @@ void __virtio_unbreak_device(struct virtio_device *dev)
list_for_each_entry(_vq, &dev->vqs, list) {
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);
+#endif
dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
{
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index d8fdf170637c..a63120477ae1 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -131,7 +131,9 @@ 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);
+#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+void __virtio_device_ready(struct virtio_device *dev);
+#endif
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 b47c2e7ed0ee..472d4703d499 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -260,22 +260,22 @@ void virtio_device_ready(struct virtio_device *dev)
#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
/*
* The virtio_synchronize_cbs() makes sure vring_interrupt()
- * will see the driver specific setup if it sees vq->broken
- * as false (even if the notifications come before DRIVER_OK).
+ * will see the driver specific setup if it sees vq->ready
+ * as true (even if the notifications come before DRIVER_OK).
*/
virtio_synchronize_cbs(dev);
- __virtio_unbreak_device(dev);
+ __virtio_device_ready(dev);
#endif
/*
- * 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->ready as true so
* we won't lose any notification.
*/
dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
--
2.25.1