c624896e48
Rather than explicitly handing the features to the lower-level, we just hand the virtio_device and have it set the features. This make it clear that it has the chance to manipulate the features of the device at this point (and that all feature negotiation is already done). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
130 lines
4.7 KiB
C
130 lines
4.7 KiB
C
#ifndef _LINUX_VIRTIO_CONFIG_H
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#define _LINUX_VIRTIO_CONFIG_H
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/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
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* anyone can use the definitions to implement compatible drivers/servers. */
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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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/* Some virtio feature bits (currently bits 28 through 31) are reserved for the
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* transport being used (eg. virtio_ring), the rest are per-device feature
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* bits. */
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#define VIRTIO_TRANSPORT_F_START 28
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#define VIRTIO_TRANSPORT_F_END 32
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/* Do we get callbacks when the ring is completely used, even if we've
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* suppressed them? */
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#define VIRTIO_F_NOTIFY_ON_EMPTY 24
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#ifdef __KERNEL__
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#include <linux/virtio.h>
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/**
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* virtio_config_ops - operations for configuring a virtio device
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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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* @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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* @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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* @get_features: get the array of feature bits for this device.
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* vdev: the virtio_device
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* Returns the first 32 feature bits (all we currently need).
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* @finalize_features: confirm what device features we'll be using.
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* vdev: the virtio_device
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* This gives the final feature bits for the device: it can change
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* the dev->feature bits if it wants.
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*/
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struct virtio_config_ops
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{
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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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u32 (*get_features)(struct virtio_device *vdev);
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void (*finalize_features)(struct virtio_device *vdev);
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};
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/* If driver didn't advertise the feature, it will never appear. */
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void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
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unsigned int fbit);
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/**
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* virtio_has_feature - helper to determine if this device has this feature.
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* @vdev: the device
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* @fbit: the feature bit
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*/
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static inline bool virtio_has_feature(const struct virtio_device *vdev,
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unsigned int fbit)
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{
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/* Did you forget to fix assumptions on max features? */
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if (__builtin_constant_p(fbit))
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BUILD_BUG_ON(fbit >= 32);
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virtio_check_driver_offered_feature(vdev, fbit);
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return test_bit(fbit, vdev->features);
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}
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/**
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* virtio_config_val - look for a feature and get a virtio config entry.
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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 config value is copied into whatever is pointed to by v. */
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#define virtio_config_val(vdev, fbit, offset, v) \
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virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
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static inline int virtio_config_buf(struct virtio_device *vdev,
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unsigned int fbit,
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unsigned int offset,
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void *buf, unsigned len)
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{
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if (!virtio_has_feature(vdev, fbit))
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return -ENOENT;
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vdev->config->get(vdev, offset, buf, len);
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return 0;
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}
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#endif /* __KERNEL__ */
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#endif /* _LINUX_VIRTIO_CONFIG_H */
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