On Wednesday 09 January 2008 03:18:13 Avi Kivity wrote:
> Marcelo Tosatti wrote:
> > Do you have any suggestion on how to retrieve the IRQ of the virtio
> > device, or some other notification mechanism?
Unfortunately, irqs are logically assigned to virtio queues, not devices. Yet
configuration info is per-device.
> One way would be to send a "look at config" queue message, but it seems
> that it is a fairly generic operation. Maybe virtio can add support for
> it, with a new callback.
This is the first time we've had to do this, but I don't think it's the last,
so we should consider it carefully.
Chatted with Anthony, and this is what we came up with:
===
virtio: configuration change callback
Various drivers want to know when their configuration information
changes: the balloon driver is the immediate user, but the network
driver may one day have a "carrier" status as well.
This introduces that callback, and adds it to the virtio PCI
implementation.
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_pci.c | 10 ++++++++++
include/linux/virtio.h | 3 +++
include/linux/virtio_pci.h | 3 +++
3 files changed, 16 insertions(+)
diff -r 7494c7702462 drivers/virtio/virtio_pci.c
--- a/drivers/virtio/virtio_pci.c Wed Jan 09 11:00:21 2008 +1100
+++ b/drivers/virtio/virtio_pci.c Wed Jan 09 11:18:19 2008 +1100
@@ -184,6 +184,16 @@ static irqreturn_t vp_interrupt(int irq,
/* It's definitely not us if the ISR was not high */
if (!isr)
return IRQ_NONE;
+
+ /* Configuration change? Tell driver if it wants to know. */
+ if (isr & VIRTIO_PCI_ISR_CONFIG) {
+ struct virtio_driver *drv;
+ drv = container_of(vp_dev->vdev.dev.driver,
+ struct virtio_driver, driver);
+
+ if (drv->config_changed)
+ drv->config_changed(&vp_dev->vdev);
+ }
spin_lock(&vp_dev->lock);
list_for_each_entry(info, &vp_dev->virtqueues, node) {
diff -r 7494c7702462 include/linux/virtio.h
--- a/include/linux/virtio.h Wed Jan 09 11:00:21 2008 +1100
+++ b/include/linux/virtio.h Wed Jan 09 11:18:19 2008 +1100
@@ -98,12 +98,15 @@ void unregister_virtio_device(struct vir
* @probe: the function to call when a device is found. Returns a token for
* remove, or PTR_ERR().
* @remove: the function when a device is removed.
+ * @config_changed: optional function to call when the device configuration
+ * changes; may be called in interrupt context.
*/
struct virtio_driver {
struct device_driver driver;
const struct virtio_device_id *id_table;
int (*probe)(struct virtio_device *dev);
void (*remove)(struct virtio_device *dev);
+ void (*config_changed)(struct virtio_device *dev);
};
int register_virtio_driver(struct virtio_driver *drv);
diff -r 7494c7702462 include/linux/virtio_pci.h
--- a/include/linux/virtio_pci.h Wed Jan 09 11:00:21 2008 +1100
+++ b/include/linux/virtio_pci.h Wed Jan 09 11:18:19 2008 +1100
@@ -45,6 +45,9 @@
* a read-and-acknowledge. */
#define VIRTIO_PCI_ISR 19
+/* The bit of the ISR which indicates a device configuration change. */
+#define VIRTIO_PCI_ISR_CONFIG 0x2
+
/* The remaining space is defined by each driver as the per-driver
* configuration space */
#define VIRTIO_PCI_CONFIG 20
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