Messages in this thread Patch in this message | | | From | Alexander Atanasov <> | Subject | [PATCH v3 1/1] virtio: Restore semantics of vq->broken in virtqueues and improve irq handling | Date | Mon, 1 Aug 2022 09:39:41 +0000 |
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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.
With the new flag improve the logic of IRQ handling like this: Until the driver is ready return IRQ_HANDLED so the IRQ does not get disabled while starting up. If the driver gets broken return IRQ_NONE so the IRQ gets disabled.
Signed-off-by: Alexander Atanasov <alexander.atanasov@virtuozzo.com> --- drivers/virtio/virtio_ring.c | 34 ++++++++++++++++++++++------------ include/linux/virtio.h | 4 +++- include/linux/virtio_config.h | 12 ++++++------ 3 files changed, 31 insertions(+), 19 deletions(-)
V2: Reworked on top of config option to disable the hardening. V3: Changed irq handling logic depending on the flags
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 643ca779fcc6..a385d563c71f 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; @@ -2160,13 +2162,21 @@ irqreturn_t vring_interrupt(int irq, void *_vq) if (unlikely(vq->broken)) { #ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION dev_warn_once(&vq->vq.vdev->dev, - "virtio vring IRQ raised before DRIVER_OK"); + "virtio vring IRQ raised for broken vq"); return IRQ_NONE; #else return IRQ_HANDLED; #endif } +#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_HANDLED; + } +#endif + /* Just a hint for performance: so it's ok that this can be racy! */ if (vq->event) vq->event_triggered = true; @@ -2207,10 +2217,9 @@ 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 +2438,15 @@ 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 +2454,12 @@ 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
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