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Subject[RFC PATCH 2/2] Assign a new irq handler while irqfd enabled
Date
From: Li Liu <john.liuli@huawei.com>

This irq handler will get the interrupt reason from a
shared memory. And will be assigned only while irqfd
enabled.

Signed-off-by: Li Liu <john.liuli@huawei.com>
---
drivers/virtio/virtio_mmio.c | 34 ++++++++++++++++++++++++++++++++--
1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 28ddb55..7229605 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -259,7 +259,31 @@ static irqreturn_t vm_interrupt(int irq, void *opaque)
return ret;
}

+/* Notify all virtqueues on an interrupt. */
+static irqreturn_t vm_interrupt_irqfd(int irq, void *opaque)
+{
+ struct virtio_mmio_device *vm_dev = opaque;
+ struct virtio_mmio_vq_info *info;
+ unsigned long status;
+ unsigned long flags;
+ irqreturn_t ret = IRQ_NONE;

+ /* Read the interrupt reason and reset it */
+ status = *vm_dev->isr_mem;
+ *vm_dev->isr_mem = 0x0;
+
+ if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)) {
+ virtio_config_changed(&vm_dev->vdev);
+ ret = IRQ_HANDLED;
+ }
+
+ spin_lock_irqsave(&vm_dev->lock, flags);
+ list_for_each_entry(info, &vm_dev->virtqueues, node)
+ ret |= vring_interrupt(irq, info->vq);
+ spin_unlock_irqrestore(&vm_dev->lock, flags);
+
+ return ret;
+}

static void vm_del_vq(struct virtqueue *vq)
{
@@ -391,6 +415,7 @@ error_available:
return ERR_PTR(err);
}

+#define VIRTIO_MMIO_F_IRQFD (1 << 7)
static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
struct virtqueue *vqs[],
vq_callback_t *callbacks[],
@@ -400,8 +425,13 @@ static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
int i, err;

- err = request_irq(irq, vm_interrupt, IRQF_SHARED,
- dev_name(&vdev->dev), vm_dev);
+ if (*vm_dev->isr_mem & VIRTIO_MMIO_F_IRQFD) {
+ err = request_irq(irq, vm_interrupt_irqfd, IRQF_SHARED,
+ dev_name(&vdev->dev), vm_dev);
+ } else {
+ err = request_irq(irq, vm_interrupt, IRQF_SHARED,
+ dev_name(&vdev->dev), vm_dev);
+ }
if (err)
return err;

--
1.7.9.5



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