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Date: Wed, 5 Nov 2014 11:08:34 +0100
From: Antonios Motakis <a.motakis@...tualopensystems.com>
To: Alex Williamson <alex.williamson@...hat.com>
Cc: kvm-arm <kvmarm@...ts.cs.columbia.edu>,
Linux IOMMU <iommu@...ts.linux-foundation.org>,
Will Deacon <will.deacon@....com>,
VirtualOpenSystems Technical Team <tech@...tualopensystems.com>,
Christoffer Dall <christoffer.dall@...aro.org>,
Eric Auger <eric.auger@...aro.org>,
Kim Phillips <kim.phillips@...escale.com>,
Marc Zyngier <marc.zyngier@....com>,
"open list:VFIO DRIVER" <kvm@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 12/19] vfio/platform: trigger an interrupt via eventfd
On Fri, Oct 31, 2014 at 8:36 PM, Alex Williamson
<alex.williamson@...hat.com> wrote:
> On Mon, 2014-10-27 at 19:07 +0100, Antonios Motakis wrote:
>> This patch allows to set an eventfd for a patform 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@...tualopensystems.com>
>> ---
>> drivers/vfio/platform/vfio_platform_irq.c | 93 ++++++++++++++++++++++++++-
>> drivers/vfio/platform/vfio_platform_private.h | 2 +
>> 2 files changed, 93 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
>> index 007b386..2ac8ed7 100644
>> --- a/drivers/vfio/platform/vfio_platform_irq.c
>> +++ b/drivers/vfio/platform/vfio_platform_irq.c
>> @@ -45,11 +45,91 @@ 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_MASKABLE)
>> + 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,
>> @@ -95,7 +175,11 @@ 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;
>
> This is a bit confusing because edge interrupts can support masking, but
> they don't require it. Level interrupts really must support masking
> because we need to mask them on the host and therefore the user needs to
> be able to unmask them (ignoring the irq prioritization thing you guys
> can do on arm). So this works, but I would really have expected
> VFIO_IRQ_INFO_AUTOMASKED here and in the above function.
You're right, it will be clearer by using automasked as the defining
property for level sensitive interrupts.
>
>> +
>> vdev->irqs[i].count = 1;
>> vdev->irqs[i].hwirq = hwirq;
>> }
>> @@ -110,6 +194,11 @@ 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 ffa2459..a3f2411 100644
>> --- a/drivers/vfio/platform/vfio_platform_private.h
>> +++ b/drivers/vfio/platform/vfio_platform_private.h
>> @@ -28,6 +28,8 @@ struct vfio_platform_irq {
>> u32 flags;
>> u32 count;
>> int hwirq;
>> + char *name;
>> + struct eventfd_ctx *trigger;
>> };
>>
>> struct vfio_platform_region {
>
>
>
--
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