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f94682dde5
Allows maintaining extra context per vq. For ease of use, passing in NULL is legal and disables the feature for all vqs. Includes fixes by Christian for s390, acked by Cornelia. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
115 lines
2.9 KiB
C
115 lines
2.9 KiB
C
#ifndef _LINUX_VIRTIO_RING_H
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#define _LINUX_VIRTIO_RING_H
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#include <asm/barrier.h>
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#include <linux/irqreturn.h>
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#include <uapi/linux/virtio_ring.h>
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/*
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* Barriers in virtio are tricky. Non-SMP virtio guests can't assume
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* they're not on an SMP host system, so they need to assume real
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* barriers. Non-SMP virtio hosts could skip the barriers, but does
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* anyone care?
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*
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* For virtio_pci on SMP, we don't need to order with respect to MMIO
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* accesses through relaxed memory I/O windows, so virt_mb() et al are
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* sufficient.
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*
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* For using virtio to talk to real devices (eg. other heterogeneous
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* CPUs) we do need real barriers. In theory, we could be using both
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* kinds of virtio, so it's a runtime decision, and the branch is
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* actually quite cheap.
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*/
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static inline void virtio_mb(bool weak_barriers)
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{
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if (weak_barriers)
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virt_mb();
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else
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mb();
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}
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static inline void virtio_rmb(bool weak_barriers)
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{
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if (weak_barriers)
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virt_rmb();
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else
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rmb();
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}
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static inline void virtio_wmb(bool weak_barriers)
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{
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if (weak_barriers)
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virt_wmb();
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else
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wmb();
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}
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static inline void virtio_store_mb(bool weak_barriers,
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__virtio16 *p, __virtio16 v)
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{
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if (weak_barriers) {
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virt_store_mb(*p, v);
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} else {
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WRITE_ONCE(*p, v);
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mb();
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}
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}
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struct virtio_device;
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struct virtqueue;
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/*
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* Creates a virtqueue and allocates the descriptor ring. If
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* may_reduce_num is set, then this may allocate a smaller ring than
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* expected. The caller should query virtqueue_get_ring_size to learn
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* the actual size of the ring.
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*/
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struct virtqueue *vring_create_virtqueue(unsigned int index,
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unsigned int num,
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unsigned int vring_align,
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struct virtio_device *vdev,
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bool weak_barriers,
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bool may_reduce_num,
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bool ctx,
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bool (*notify)(struct virtqueue *vq),
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void (*callback)(struct virtqueue *vq),
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const char *name);
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/* Creates a virtqueue with a custom layout. */
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struct virtqueue *__vring_new_virtqueue(unsigned int index,
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struct vring vring,
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struct virtio_device *vdev,
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bool weak_barriers,
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bool ctx,
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bool (*notify)(struct virtqueue *),
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void (*callback)(struct virtqueue *),
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const char *name);
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/*
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* Creates a virtqueue with a standard layout but a caller-allocated
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* ring.
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*/
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struct virtqueue *vring_new_virtqueue(unsigned int index,
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unsigned int num,
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unsigned int vring_align,
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struct virtio_device *vdev,
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bool weak_barriers,
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bool ctx,
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void *pages,
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bool (*notify)(struct virtqueue *vq),
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void (*callback)(struct virtqueue *vq),
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const char *name);
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/*
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* Destroys a virtqueue. If created with vring_create_virtqueue, this
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* also frees the ring.
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*/
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void vring_del_virtqueue(struct virtqueue *vq);
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/* Filter out transport-specific feature bits. */
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void vring_transport_features(struct virtio_device *vdev);
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irqreturn_t vring_interrupt(int irq, void *_vq);
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#endif /* _LINUX_VIRTIO_RING_H */
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