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Date: Wed, 22 Oct 2014 15:55:56 +0200
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 v8 13/18] vfio/platform: support for maskable and
automasked interrupts
On Tue, Oct 21, 2014 at 7:47 PM, Alex Williamson
<alex.williamson@...hat.com> wrote:
> 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.
>
Ok, I shall implement separate handlers then.
>>
>> 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 {
>
>
>
--
Antonios Motakis
Virtual Open Systems
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