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Date: Tue, 21 Oct 2014 11:47:18 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Antonios Motakis <a.motakis@...tualopensystems.com>
Cc: kvmarm@...ts.cs.columbia.edu, iommu@...ts.linux-foundation.org,
will.deacon@....com, tech@...tualopensystems.com,
christoffer.dall@...aro.org, eric.auger@...aro.org,
kim.phillips@...escale.com, marc.zyngier@....com,
"open list:VFIO DRIVER" <kvm@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 13/18] vfio/platform: support for maskable and
automasked interrupts
On Mon, 2014-10-13 at 15:10 +0200, Antonios Motakis wrote:
> Adds support to mask interrupts, and also for automasked interrupts.
> Level sensitive interrupts are exposed as automasked interrupts and
> are masked and disabled automatically when they fire.
>
> Signed-off-by: Antonios Motakis <a.motakis@...tualopensystems.com>
> ---
> drivers/vfio/platform/vfio_platform_irq.c | 94 +++++++++++++++++++++++++--
> drivers/vfio/platform/vfio_platform_private.h | 2 +
> 2 files changed, 91 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index 4359b9c..7620a17 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -31,27 +31,103 @@
>
> #include "vfio_platform_private.h"
>
> +static void vfio_platform_mask(struct vfio_platform_irq *irq_ctx)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&irq_ctx->lock, flags);
> +
> + if (!irq_ctx->masked) {
> + disable_irq(irq_ctx->hwirq);
> + irq_ctx->masked = true;
> + }
> +
> + spin_unlock_irqrestore(&irq_ctx->lock, flags);
> +}
> +
> static int vfio_platform_set_irq_mask(struct vfio_platform_device *vdev,
> unsigned index, unsigned start,
> unsigned count, uint32_t flags, void *data)
> {
> - return -EINVAL;
> + if (start != 0 || count != 1)
> + return -EINVAL;
> +
> + if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
> + return -EINVAL; /* not implemented yet */
> +
> + if (flags & VFIO_IRQ_SET_DATA_NONE) {
> + vfio_platform_mask(&vdev->irqs[index]);
> +
> + } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
> + uint8_t mask = *(uint8_t *)data;
> +
> + if (mask)
> + vfio_platform_mask(&vdev->irqs[index]);
> + }
> +
> + return 0;
> +}
> +
> +static void vfio_platform_unmask(struct vfio_platform_irq *irq_ctx)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&irq_ctx->lock, flags);
> +
> + if (irq_ctx->masked) {
> + enable_irq(irq_ctx->hwirq);
> + irq_ctx->masked = false;
> + }
> +
> + spin_unlock_irqrestore(&irq_ctx->lock, flags);
> }
>
> static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
> unsigned index, unsigned start,
> unsigned count, uint32_t flags, void *data)
> {
> - return -EINVAL;
> + if (start != 0 || count != 1)
> + return -EINVAL;
> +
> + if (flags & VFIO_IRQ_SET_DATA_EVENTFD)
> + return -EINVAL; /* not implemented yet */
> +
> + if (flags & VFIO_IRQ_SET_DATA_NONE) {
> + vfio_platform_unmask(&vdev->irqs[index]);
> +
> + } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
> + uint8_t unmask = *(uint8_t *)data;
> +
> + if (unmask)
> + vfio_platform_unmask(&vdev->irqs[index]);
> + }
> +
> + return 0;
> }
>
> static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
> {
> struct vfio_platform_irq *irq_ctx = dev_id;
> + unsigned long flags;
> + int ret = IRQ_NONE;
>
> - eventfd_signal(irq_ctx->trigger, 1);
> + spin_lock_irqsave(&irq_ctx->lock, flags);
> +
> + if (!irq_ctx->masked) {
> + ret = IRQ_HANDLED;
> +
> + if (irq_ctx->flags & VFIO_IRQ_INFO_AUTOMASKED) {
> + disable_irq_nosync(irq_ctx->hwirq);
> + irq_ctx->masked = true;
> + }
> + }
>
> - return IRQ_HANDLED;
> + spin_unlock_irqrestore(&irq_ctx->lock, flags);
> +
> + if (ret == IRQ_HANDLED)
> + eventfd_signal(irq_ctx->trigger, 1);
> +
> + return ret;
> }
If you actually have edge interrupts, you're unnecessarily penalizing
them with the spinlock here. You could do like vfio-pci and only
advertise level interrupts as maskable then use separate edge vs level
handlers.
>
> static int vfio_set_trigger(struct vfio_platform_device *vdev,
> @@ -169,9 +245,17 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
> if (hwirq < 0)
> goto err;
>
> - vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
> + spin_lock_init(&vdev->irqs[i].lock);
> +
> + vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD
> + | VFIO_IRQ_INFO_MASKABLE;
> +
> + if (irq_get_trigger_type(hwirq) & IRQ_TYPE_LEVEL_MASK)
> + vdev->irqs[i].flags |= VFIO_IRQ_INFO_AUTOMASKED;
> +
> vdev->irqs[i].count = 1;
> vdev->irqs[i].hwirq = hwirq;
> + vdev->irqs[i].masked = false;
> }
>
> vdev->num_irqs = cnt;
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 47af6e0..65e80e7 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -30,6 +30,8 @@ struct vfio_platform_irq {
> int hwirq;
> char *name;
> struct eventfd_ctx *trigger;
> + bool masked;
> + spinlock_t lock;
> };
>
> struct vfio_platform_region {
--
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