This patch tries to make sure the virtio interrupt handler for MMIO
won't be called after a reset and before virtio_device_ready(). We
can't use IRQF_NO_AUTOEN since we're using shared interrupt
(IRQF_SHARED). So this patch tracks the interrupt enabling status in a
new intr_soft_enabled variable and toggle it during in
vm_disable/enable_interrupts(). The MMIO interrupt handler will check
intr_soft_enabled before processing the actual interrupt.
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/virtio/virtio_mmio.c | 37 ++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 56128b9c46eb..796f0c789b09 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -90,6 +90,7 @@ struct virtio_mmio_device {
/* a list of queues so we can dispatch IRQs */
spinlock_t lock;
struct list_head virtqueues;
+ bool intr_soft_enabled;
};
struct virtio_mmio_vq_info {
@@ -100,7 +101,37 @@ struct virtio_mmio_vq_info {
struct list_head node;
};
+/* disable irq handlers */
+void vm_disable_cbs(struct virtio_device *vdev)
+{
+ struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+ int irq = platform_get_irq(vm_dev->pdev, 0);
+ /*
+ * The below synchronize() guarantees that any
+ * interrupt for this line arriving after
+ * synchronize_irq() has completed is guaranteed to see
+ * intx_soft_enabled == false.
+ */
+ WRITE_ONCE(vm_dev->intr_soft_enabled, false);
+ synchronize_irq(irq);
+}
+
+/* enable irq handlers */
+void vm_enable_cbs(struct virtio_device *vdev)
+{
+ struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+ int irq = platform_get_irq(vm_dev->pdev, 0);
+
+ disable_irq(irq);
+ /*
+ * The above disable_irq() provides TSO ordering and
+ * as such promotes the below store to store-release.
+ */
+ WRITE_ONCE(vm_dev->intr_soft_enabled, true);
+ enable_irq(irq);
+ return;
+}
/* Configuration interface */
@@ -262,6 +293,8 @@ static void vm_reset(struct virtio_device *vdev)
/* 0 status means a reset. */
writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
+ /* Disable VQ/configuration callbacks. */
+ vm_disable_cbs(vdev);
}
@@ -288,6 +321,9 @@ static irqreturn_t vm_interrupt(int irq, void *opaque)
unsigned long flags;
irqreturn_t ret = IRQ_NONE;
+ if (!READ_ONCE(vm_dev->intr_soft_enabled))
+ return IRQ_NONE;
+
/* Read and acknowledge interrupts */
status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
@@ -529,6 +565,7 @@ static bool vm_get_shm_region(struct virtio_device *vdev,
}
static const struct virtio_config_ops virtio_mmio_config_ops = {
+ .enable_cbs = vm_enable_cbs,
.get = vm_get,
.set = vm_set,
.generation = vm_generation,
--
2.25.1
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
