unimore/kernel-hacking-2024-linux-steffo
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virtio: add API to enable VQs early

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virtio spec 0.9.X requires DRIVER_OK to be set before
VQs are used, but some drivers use VQs before probe
function returns.
Since DRIVER_OK is set after probe, this violates the spec.

Even though under virtio 1.0 transitional devices support this
behaviour, we want to make it possible for those early callers to become
spec compliant and eventually support non-transitional devices.

Add API for drivers to call before using VQs.

Sets DRIVER_OK internally.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Michael S. Tsirkin 2014-10-15 10:22:30 +10:30 committed by Rusty Russell
parent 507613bf31
commit 3569db5930
1 changed files with 17 additions and 0 deletions
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17
include/linux/virtio_config.h
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@ -109,6 +109,23 @@ struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
return vq;
}
/**
* virtio_device_ready - enable vq use in probe function
* @vdev: the device
*
* Driver must call this to use vqs in the probe function.
*
* Note: vqs are enabled automatically after probe returns.
*/
static inline
void virtio_device_ready(struct virtio_device *dev)
{
unsigned status = dev->config->get_status(dev);
BUG_ON(status & VIRTIO_CONFIG_S_DRIVER_OK);
dev->config->set_status(dev, status | VIRTIO_CONFIG_S_DRIVER_OK);
}
static inline
const char *virtio_bus_name(struct virtio_device *vdev)
{