vfio/platform: support for level sensitive interrupts

Level sensitive interrupts are exposed as maskable and automasked
interrupts and are masked and disabled automatically when they fire.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
[Baptiste Reynal: Move masked interrupt initialization from "vfio/platform:
trigger an interrupt via eventfd"]
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

2 files changed, 102 insertions, 3 deletions

diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index 611ec80db63a..e0e638841d0b 100644
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -23,12 +23,59 @@
 
 #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_nosync(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 (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
+                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,
@@ -36,7 +83,50 @@ static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
                                         unsigned count, uint32_t flags,
                                         void *data)
 {
-        return -EINVAL;
+        if (start != 0 || count != 1)
+                return -EINVAL;
+
+        if (!(vdev->irqs[index].flags & VFIO_IRQ_INFO_MASKABLE))
+                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_automasked_irq_handler(int irq, void *dev_id)
+{
+        struct vfio_platform_irq *irq_ctx = dev_id;
+        unsigned long flags;
+        int ret = IRQ_NONE;
+
+        spin_lock_irqsave(&irq_ctx->lock, flags);
+
+        if (!irq_ctx->masked) {
+                ret = IRQ_HANDLED;
+
+                /* automask maskable interrupts */
+                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 irqreturn_t vfio_irq_handler(int irq, void *dev_id)
@@ -78,6 +168,7 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
 
         irq->trigger = trigger;
 
+        irq_set_status_flags(irq->hwirq, IRQ_NOAUTOEN);
         ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
         if (ret) {
                 kfree(irq->name);
@@ -86,6 +177,9 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
                 return ret;
         }
 
+        if (!irq->masked)
+                enable_irq(irq->hwirq);
+
         return 0;
 }
 
@@ -98,7 +192,7 @@ static int vfio_platform_set_irq_trigger(struct vfio_platform_device *vdev,
         irq_handler_t handler;
 
         if (vdev->irqs[index].flags & VFIO_IRQ_INFO_AUTOMASKED)
-                return -EINVAL; /* not implemented */
+                handler = vfio_automasked_irq_handler;
         else
                 handler = vfio_irq_handler;
 
@@ -170,6 +264,8 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
                 if (hwirq < 0)
                         goto err;
 
+                spin_lock_init(&vdev->irqs[i].lock);
+
                 vdev->irqs[i].flags = VFIO_IRQ_INFO_EVENTFD;
 
                 if (irq_get_trigger_type(hwirq) & IRQ_TYPE_LEVEL_MASK)
@@ -178,6 +274,7 @@ int vfio_platform_irq_init(struct vfio_platform_device *vdev)
 
                 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 aa01cc36af53..ff2db1d20a26 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -33,6 +33,8 @@ struct vfio_platform_irq {
         int                     hwirq;
         char                    *name;
         struct eventfd_ctx      *trigger;
+        bool                    masked;
+        spinlock_t              lock;
 };
 
 struct vfio_platform_region {