[PATCH v14 12/20] vfio/platform: trigger an interrupt via eventfd

Baptiste Reynal
2015-03-02T16:59:52Z

From: Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>

This patch allows to set an eventfd for a platform device's interrupt,
and also to trigger the interrupt eventfd from userspace for testing.
Level sensitive interrupts are marked as maskable and are handled in
a later patch. Edge triggered interrupts are not advertised as maskable
and are implemented here using a simple and efficient IRQ handler.

Signed-off-by: Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
[Baptiste Reynal: fix masked interrupt initialization]
Signed-off-by: Baptiste Reynal <b.reynal-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
---
drivers/vfio/platform/vfio_platform_irq.c | 94 ++++++++++++++++++++++++++-
drivers/vfio/platform/vfio_platform_private.h | 2 +
2 files changed, 94 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index df5c919..611ec80 100644
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -39,12 +39,92 @@ static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
return -EINVAL;
}

+static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
+{
+ struct vfio_platform_irq *irq_ctx = dev_id;
+
+ eventfd_signal(irq_ctx->trigger, 1);
+
+ return IRQ_HANDLED;
+}
+
+static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
+ int fd, irq_handler_t handler)
+{
+ struct vfio_platform_irq *irq = &vdev->irqs[index];
+ struct eventfd_ctx *trigger;
+ int ret;
+
+ if (irq->trigger) {
+ free_irq(irq->hwirq, irq);
+ kfree(irq->name);
+ eventfd_ctx_put(irq->trigger);
+ irq->trigger = NULL;
+ }
+
+ if (fd < 0) /* Disable only */
+ return 0;
+
+ irq->name = kasprintf(GFP_KERNEL, "vfio-irq[%d](%s)",
+ irq->hwirq, vdev->name);
+ if (!irq->name)
+ return -ENOMEM;
+
+ trigger = eventfd_ctx_fdget(fd);
+ if (IS_ERR(trigger)) {
+ kfree(irq->name);
+ return PTR_ERR(trigger);
+ }
+
+ irq->trigger = trigger;
+
+ ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
+ if (ret) {
+ kfree(irq->name);
+ eventfd_ctx_put(trigger);
+ irq->trigger = NULL;
+ return ret;
+ }
+
+ return 0;
+}
+
static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
unsigned index, unsigned start,
unsigned count, uint32_t flags,
void *data)
{
- return -EINVAL;
+ struct vfio_platform_irq *irq = &vdev->irqs[index];
+ irq_handler_t handler;
+
+ if (vdev->irqs[index].flags & VFIO_IRQ_INFO_AUTOMASKED)
+ return -EINVAL; /* not implemented */
+ else
+ handler = vfio_irq_handler;
+
+ if (!count && (flags & VFIO_IRQ_SET_DATA_NONE))
+ return vfio_set_trigger(vdev, index, -1, handler);
+
+ if (start != 0 || count != 1)
+ return -EINVAL;
+
+ if (flags & VFIO_IRQ_SET_DATA_EVENTFD) {
+ int32_t fd = *(int32_t *)data;
+
+ return vfio_set_trigger(vdev, index, fd, handler);
+ }
+
+ if (flags & VFIO_IRQ_SET_DATA_NONE) {
+ handler(irq->hwirq, irq);
+
+ } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
+ uint8_t trigger = *(uint8_t *)data;
+
+ if (trigger)
+ handler(irq->hwirq, irq);
+ }
+
+ return 0;
}

int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
@@ -90,7 +170,12 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
if (hwirq < 0)
goto err;

- vdev->irqs[i].flags = 0;
+ vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
+
+ if (irq_get_trigger_type(hwirq) & IRQ_TYPE_LEVEL_MASK)
+ vdev->irqs[i].flags |= VFIO_IRQ_INFO_MASKABLE
+ | VFIO_IRQ_INFO_AUTOMASKED;
+
vdev->irqs[i].count = 1;
vdev->irqs[i].hwirq = hwirq;
}
@@ -105,6 +190,11 @@ err:

void vfio_platform_irq_cleanup(struct vfio_platform_device *vdev)
{
+ int i;
+
+ for (i = 0; i < vdev->num_irqs; i++)
+ vfio_set_trigger(vdev, i, -1, NULL);
+
vdev->num_irqs = 0;
kfree(vdev->irqs);
}
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index b119a6c..aa01cc3 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -31,6 +31,8 @@ struct vfio_platform_irq {
u32 flags;
u32 count;
int hwirq;
+ char *name;
+ struct eventfd_ctx *trigger;
};

struct vfio_platform_region {
--
2.3.1