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Date:	Tue, 23 Sep 2014 16:46:20 +0200
From:	Antonios Motakis <a.motakis@...tualopensystems.com>
To:	alex.williamson@...hat.com, kvmarm@...ts.cs.columbia.edu,
	iommu@...ts.linux-foundation.org
Cc:	tech@...tualopensystems.com, kvm@...r.kernel.org,
	christoffer.dall@...aro.org, will.deacon@....com,
	kim.phillips@...escale.com, eric.auger@...aro.org,
	marc.zyngier@....com,
	Antonios Motakis <a.motakis@...tualopensystems.com>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCHv7 21/26] vfio/platform: support for maskable and automasked interrupts

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     | 120 ++++++++++++++++++++++++--
 drivers/vfio/platform/vfio_platform_private.h |   2 +
 2 files changed, 117 insertions(+), 5 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index 25a7825..90fa25a 100644
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -31,27 +31,129 @@
 
 #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;
+	uint8_t irq_bitmap;
+
+	if (start != 0 || count != 1)
+		return -EINVAL;
+
+	switch (flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
+	case VFIO_IRQ_SET_DATA_BOOL:
+		if (copy_from_user(&irq_bitmap, data, sizeof(uint8_t)))
+			return -EFAULT;
+
+		if (irq_bitmap != 0x1)
+			return -EINVAL;
+
+		/*
+		 * The following fall through is both intentional and safe.
+		 * VFIO_IRQ_SET_DATA_BOOL allows to handle an array of IRQs
+		 * on the same index. For VFIO platform devices we always have
+		 * one IRQ per index, so as soon as we check that the user
+		 * provided bitmap only refers to one single IRQ, we can safely
+		 * share the rest of the logic with VFIO_IRQ_SET_DATA_NONE.
+		 */
+
+	case VFIO_IRQ_SET_DATA_NONE:
+		vfio_platform_mask(&vdev->irqs[index]);
+		return 0;
+
+	case VFIO_IRQ_SET_DATA_EVENTFD: /* XXX not implemented yet */
+	default:
+		return -ENOTTY;
+	}
+
+	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;
+	uint8_t irq_bitmap;
+
+	if (start != 0 || count != 1)
+		return -EINVAL;
+
+	switch (flags & VFIO_IRQ_SET_DATA_TYPE_MASK) {
+	case VFIO_IRQ_SET_DATA_BOOL:
+		if (copy_from_user(&irq_bitmap, data, sizeof(uint8_t)))
+			return -EFAULT;
+
+		if (irq_bitmap != 0x1)
+			return -EINVAL;
+
+		/*
+		 * The following fall through is both intentional and safe,
+		 * as in vfio_platform_set_irq_mask().
+		 */
+
+	case VFIO_IRQ_SET_DATA_NONE:
+		vfio_platform_unmask(&vdev->irqs[index]);
+		return 0;
+
+	case VFIO_IRQ_SET_DATA_EVENTFD: /* XXX not implemented yet */
+	default:
+		return -ENOTTY;
+	}
+
+	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);
 
-	return IRQ_HANDLED;
+	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;
+		}
+	}
+
+	spin_unlock_irqrestore(&irq_ctx->lock, flags);
+
+	if (ret == IRQ_HANDLED)
+		eventfd_signal(irq_ctx->trigger, 1);
+
+	return ret;
 }
 
 static int vfio_set_trigger(struct vfio_platform_device *vdev,
@@ -175,9 +277,17 @@ 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 765b371..500e299 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 {
-- 
1.8.3.2

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