2010-11-03 20:17:39

by Alex Williamson

Subject: [PATCH] vfio: Fix PCI 2.3 shared interrupt

Trying to be too clever with setting the irq_disabled flag. PCI 2.3
disabled devices can still share IRQs, which can lead to clearing
the irq_disabled flag, preventing the EOI from registering, and leaving
the device without interrupts. Interrupt handler should only ever
set irq_disabled and we can exit earlier to avoid the config space
access if we know we're disabled.

Signed-off-by: Alex Williamson <[email protected]>
---

drivers/vfio/vfio_intrs.c | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/vfio/vfio_intrs.c b/drivers/vfio/vfio_intrs.c
index 604082c..73e3deb 100644
--- a/drivers/vfio/vfio_intrs.c
+++ b/drivers/vfio/vfio_intrs.c
@@ -57,6 +57,12 @@ irqreturn_t vfio_interrupt(int irq, void *dev_id)

spin_lock_irq(&vdev->irqlock);

+ /* INTX disabled interrupts can still be shared */
+ if (vdev->irq_disabled) {
+ spin_unlock_irq(&vdev->irqlock);
+ return ret;
+ }
+
if (vdev->pci_2_3) {
pci_block_user_cfg_access(pdev);

@@ -87,7 +93,8 @@ done:
ret = IRQ_HANDLED;
}

- vdev->irq_disabled = (ret == IRQ_HANDLED);
+ if (ret == IRQ_HANDLED)
+ vdev->irq_disabled = true;

spin_unlock_irq(&vdev->irqlock);

2010-11-03 21:03:18

by Tom Lyon

Subject: Re: [PATCH] vfio: Fix PCI 2.3 shared interrupt

Applied.

On Wednesday, November 03, 2010 01:17:33 pm Alex Williamson wrote:
> Trying to be too clever with setting the irq_disabled flag. PCI 2.3
> disabled devices can still share IRQs, which can lead to clearing
> the irq_disabled flag, preventing the EOI from registering, and leaving
> the device without interrupts. Interrupt handler should only ever
> set irq_disabled and we can exit earlier to avoid the config space
> access if we know we're disabled.
>
> Signed-off-by: Alex Williamson <[email protected]>
> ---
>
> drivers/vfio/vfio_intrs.c | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/vfio/vfio_intrs.c b/drivers/vfio/vfio_intrs.c
> index 604082c..73e3deb 100644
> --- a/drivers/vfio/vfio_intrs.c
> +++ b/drivers/vfio/vfio_intrs.c
> @@ -57,6 +57,12 @@ irqreturn_t vfio_interrupt(int irq, void *dev_id)
>
> spin_lock_irq(&vdev->irqlock);
>
> + /* INTX disabled interrupts can still be shared */
> + if (vdev->irq_disabled) {
> + spin_unlock_irq(&vdev->irqlock);
> + return ret;
> + }
> +
> if (vdev->pci_2_3) {
> pci_block_user_cfg_access(pdev);
>
> @@ -87,7 +93,8 @@ done:
> ret = IRQ_HANDLED;
> }
>
> - vdev->irq_disabled = (ret == IRQ_HANDLED);
> + if (ret == IRQ_HANDLED)
> + vdev->irq_disabled = true;
>
> spin_unlock_irq(&vdev->irqlock);