Re: [PATCH 01/10] vfio: platform: Add automasked field to vfio_platform_irq

Alex Williamson
2017-05-31T17:38:05Z

On Tue, 30 May 2017 14:45:54 +0200
Auger Eric <eric.auger@redhat.com> wrote:

> Hi Marc,
>
> On 25/05/2017 20:05, Marc Zyngier wrote:
> > Hi Eric,
> >
> > On Wed, May 24 2017 at 10:13:14 pm BST, 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/platform/vfio_platform_irq.c | 10 ++++++----
> >> drivers/vfio/platform/vfio_platform_private.h | 1 +
> >> 2 files changed, 7 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> >> index 46d4750..831f0b0 100644
> >> --- a/drivers/vfio/platform/vfio_platform_irq.c
> >> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> >> @@ -29,7 +29,7 @@ static void vfio_platform_mask(struct vfio_platform_irq *irq_ctx)
> >>
> >> spin_lock_irqsave(&irq_ctx->lock, flags);
> >>
> >> - if (!irq_ctx->masked) {
> >> + if (!irq_ctx->masked && !irq_ctx->automasked) {
> >
> > Could you please expand a bit on what this automasked variable covers?
> > It'd be good to document how masked and automasked differ in behaviour.
>
> Yes sure. So automasked is set by the physical IRQ handler only, for
> level sensitive IRQ (AUTOMASKED interrupts). masked is set through the
> userspace API (VFIO_DEVICE_SET_IRQS and ACTION_MASK) when masking the
> IRQ. VFIO ACTION_UNMASK resets both.

This would make more sense if you at the same time renamed 'masked' to
'usermasked'. Thanks,

Alex

> >
> > Also, it may be worth having a helper (is_masked?) to abstract both
> > cases.
>
> Sure
>
> Eric
> >
> >> disable_irq_nosync(irq_ctx->hwirq);
> >> irq_ctx->masked = true;
> >> }
> >> @@ -89,9 +89,10 @@ static void vfio_platform_unmask(struct vfio_platform_irq *irq_ctx)
> >>
> >> spin_lock_irqsave(&irq_ctx->lock, flags);
> >>
> >> - if (irq_ctx->masked) {
> >> + if (irq_ctx->masked || irq_ctx->automasked) {
> >> enable_irq(irq_ctx->hwirq);
> >> irq_ctx->masked = false;
> >> + irq_ctx->automasked = false;
> >> }
> >>
> >> spin_unlock_irqrestore(&irq_ctx->lock, flags);
> >> @@ -152,12 +153,12 @@ static irqreturn_t vfio_automasked_irq_handler(int irq, void *dev_id)
> >>
> >> spin_lock_irqsave(&irq_ctx->lock, flags);
> >>
> >> - if (!irq_ctx->masked) {
> >> + if (!irq_ctx->masked && !irq_ctx->automasked) {
> >> ret = IRQ_HANDLED;
> >>
> >> /* automask maskable interrupts */
> >> disable_irq_nosync(irq_ctx->hwirq);
> >> - irq_ctx->masked = true;
> >> + irq_ctx->automasked = true;
> >> }
> >>
> >> spin_unlock_irqrestore(&irq_ctx->lock, flags);
> >> @@ -315,6 +316,7 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
> >> vdev->irqs[i].count = 1;
> >> vdev->irqs[i].hwirq = hwirq;
> >> vdev->irqs[i].masked = false;
> >> + vdev->irqs[i].automasked = false;
> >> }
> >>
> >> vdev->num_irqs = cnt;
> >> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> >> index 85ffe5d..8a3cfa9 100644
> >> --- a/drivers/vfio/platform/vfio_platform_private.h
> >> +++ b/drivers/vfio/platform/vfio_platform_private.h
> >> @@ -34,6 +34,7 @@ struct vfio_platform_irq {
> >> char *name;
> >> struct eventfd_ctx *trigger;
> >> bool masked;
> >> + bool automasked;
> >> spinlock_t lock;
> >> struct virqfd *unmask;
> >> struct virqfd *mask;
> >
> > Thanks,
> >
> > M.
> >