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6e5aa7efb2
A reset function solves three problems: 1) It allows us to renegotiate features, eg. if we want to upgrade a guest driver without rebooting the guest. 2) It gives us a clean way of shutting down virtqueues: after a reset, we know that the buffers won't be used by the host, and 3) It helps the guest recover from messed-up drivers. So we remove the ->shutdown hook, and the only way we now remove feature bits is via reset. We leave it to the driver to do the reset before it deletes queues: the balloon driver, for example, needs to chat to the host in its remove function. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
110 lines
4.0 KiB
C
110 lines
4.0 KiB
C
#ifndef _LINUX_VIRTIO_CONFIG_H
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#define _LINUX_VIRTIO_CONFIG_H
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/* Virtio devices use a standardized configuration space to define their
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* features and pass configuration information, but each implementation can
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* store and access that space differently. */
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#include <linux/types.h>
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/* Status byte for guest to report progress, and synchronize features. */
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/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
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#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
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/* We have found a driver for the device. */
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#define VIRTIO_CONFIG_S_DRIVER 2
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/* Driver has used its parts of the config, and is happy */
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#define VIRTIO_CONFIG_S_DRIVER_OK 4
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/* We've given up on this device. */
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#define VIRTIO_CONFIG_S_FAILED 0x80
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#ifdef __KERNEL__
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struct virtio_device;
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/**
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* virtio_config_ops - operations for configuring a virtio device
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* @feature: search for a feature in this config
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* vdev: the virtio_device
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* bit: the feature bit
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* Returns true if the feature is supported. Acknowledges the feature
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* so the host can see it.
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* @get: read the value of a configuration field
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* vdev: the virtio_device
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* offset: the offset of the configuration field
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* buf: the buffer to write the field value into.
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* len: the length of the buffer
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* Note that contents are conventionally little-endian.
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* @set: write the value of a configuration field
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* vdev: the virtio_device
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* offset: the offset of the configuration field
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* buf: the buffer to read the field value from.
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* len: the length of the buffer
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* Note that contents are conventionally little-endian.
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* @get_status: read the status byte
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* vdev: the virtio_device
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* Returns the status byte
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* @set_status: write the status byte
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* vdev: the virtio_device
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* status: the new status byte
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* @reset: reset the device
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* vdev: the virtio device
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* After this, status and feature negotiation must be done again
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* @find_vq: find a virtqueue and instantiate it.
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* vdev: the virtio_device
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* index: the 0-based virtqueue number in case there's more than one.
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* callback: the virqtueue callback
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* Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
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* @del_vq: free a virtqueue found by find_vq().
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*/
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struct virtio_config_ops
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{
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bool (*feature)(struct virtio_device *vdev, unsigned bit);
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void (*get)(struct virtio_device *vdev, unsigned offset,
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void *buf, unsigned len);
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void (*set)(struct virtio_device *vdev, unsigned offset,
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const void *buf, unsigned len);
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u8 (*get_status)(struct virtio_device *vdev);
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void (*set_status)(struct virtio_device *vdev, u8 status);
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void (*reset)(struct virtio_device *vdev);
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struct virtqueue *(*find_vq)(struct virtio_device *vdev,
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unsigned index,
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void (*callback)(struct virtqueue *));
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void (*del_vq)(struct virtqueue *vq);
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};
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/**
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* virtio_config_val - look for a feature and get a single virtio config.
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* @vdev: the virtio device
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* @fbit: the feature bit
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* @offset: the type to search for.
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* @val: a pointer to the value to fill in.
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*
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* The return value is -ENOENT if the feature doesn't exist. Otherwise
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* the value is endian-corrected and returned in v. */
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#define virtio_config_val(vdev, fbit, offset, v) ({ \
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int _err; \
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if ((vdev)->config->feature((vdev), (fbit))) { \
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__virtio_config_val((vdev), (offset), (v)); \
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_err = 0; \
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} else \
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_err = -ENOENT; \
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_err; \
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})
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/**
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* __virtio_config_val - get a single virtio config without feature check.
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* @vdev: the virtio device
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* @offset: the type to search for.
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* @val: a pointer to the value to fill in.
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*
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* The value is endian-corrected and returned in v. */
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#define __virtio_config_val(vdev, offset, v) do { \
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BUILD_BUG_ON(sizeof(*(v)) != 1 && sizeof(*(v)) != 2 \
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&& sizeof(*(v)) != 4 && sizeof(*(v)) != 8); \
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(vdev)->config->get((vdev), (offset), (v), sizeof(*(v))); \
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switch (sizeof(*(v))) { \
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case 2: le16_to_cpus((__u16 *) v); break; \
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case 4: le32_to_cpus((__u32 *) v); break; \
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case 8: le64_to_cpus((__u64 *) v); break; \
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} \
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} while(0)
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#endif /* __KERNEL__ */
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#endif /* _LINUX_VIRTIO_CONFIG_H */
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