Re: [PATCH 04/10] VFIO: pci: Add automasked field to vfio_pci_irq_ctx

Alex Williamson
2017-05-31T18:17:37Z

On Wed, 24 May 2017 22:13:17 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> For direct EOI modality we will need to differentiate a userspace
> masking from the IRQ handler auto-masking.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> drivers/vfio/pci/vfio_pci_intrs.c | 15 +++++++++------
> drivers/vfio/pci/vfio_pci_private.h | 1 +
> 2 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
> index 1c46045..d4d377b 100644
> --- a/drivers/vfio/pci/vfio_pci_intrs.c
> +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> @@ -52,7 +52,7 @@ void vfio_pci_intx_mask(struct vfio_pci_device *vdev)
> if (unlikely(!is_intx(vdev))) {
> if (vdev->pci_2_3)
> pci_intx(pdev, 0);
> - } else if (!vdev->ctx[0].masked) {
> + } else if (!vdev->ctx[0].masked && !vdev->ctx[0].automasked) {
> /*
> * Can't use check_and_mask here because we always want to
> * mask, not just when something is pending.
> @@ -90,7 +90,8 @@ static int vfio_pci_intx_unmask_handler(void *opaque, void *unused)
> if (unlikely(!is_intx(vdev))) {
> if (vdev->pci_2_3)
> pci_intx(pdev, 1);
> - } else if (vdev->ctx[0].masked && !vdev->virq_disabled) {
> + } else if ((vdev->ctx[0].masked || vdev->ctx[0].automasked) &&
> + !vdev->virq_disabled) {
> /*
> * A pending interrupt here would immediately trigger,
> * but we can avoid that overhead by just re-sending
> @@ -103,6 +104,7 @@ static int vfio_pci_intx_unmask_handler(void *opaque, void *unused)
> enable_irq(pdev->irq);
>
> vdev->ctx[0].masked = (ret > 0);
> + vdev->ctx[0].automasked = (ret > 0);
> }

This looks suspicious, if we leave this function with the interrupt
masked, isn't it due to an automask, not a usermask?

>
> spin_unlock_irqrestore(&vdev->irqlock, flags);
> @@ -126,11 +128,12 @@ static irqreturn_t vfio_intx_handler(int irq, void *dev_id)
>
> if (!vdev->pci_2_3) {
> disable_irq_nosync(vdev->pdev->irq);
> - vdev->ctx[0].masked = true;
> + vdev->ctx[0].automasked = true;
> ret = IRQ_HANDLED;
> - } else if (!vdev->ctx[0].masked && /* may be shared */
> - pci_check_and_mask_intx(vdev->pdev)) {
> - vdev->ctx[0].masked = true;
> + } else if (!vdev->ctx[0].masked && !vdev->ctx[0].automasked &&
> + pci_check_and_mask_intx(vdev->pdev)) {
> + /* shared INTx */
> + vdev->ctx[0].automasked = true;
> ret = IRQ_HANDLED;
> }
>
> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
> index f561ac1..f7f1101 100644
> --- a/drivers/vfio/pci/vfio_pci_private.h
> +++ b/drivers/vfio/pci/vfio_pci_private.h
> @@ -35,6 +35,7 @@ struct vfio_pci_irq_ctx {
> struct virqfd *mask;
> char *name;
> bool masked;
> + bool automasked;
> struct irq_bypass_producer producer;
> };
>