qemu-e2k/include/hw/virtio/vhost-vdpa.h
Eugenio Pérez e6db5df7e2 vhost-vdpa: Do not send empty IOTLB update batches
With the introduction of the batch hinting, meaningless batches can be
created with no IOTLB updates if the memory region was skipped by
vhost_vdpa_listener_skipped_section. This is the case of host notifiers
memory regions, device un/realize, and others. This causes the vdpa
device to receive dma mapping settings with no changes, a possibly
expensive operation for nothing.

To avoid that, VHOST_IOTLB_BATCH_BEGIN hint is delayed until we have a
meaningful (not skipped section) mapping or unmapping operation, and
VHOST_IOTLB_BATCH_END is not written unless at least one of _UPDATE /
_INVALIDATE has been issued.

v3:
  * Use a bool instead of a counter avoiding potential number wrapping
  * Fix bad check on _commit
  * Move VHOST_BACKEND_F_IOTLB_BATCH check to
    vhost_vdpa_iotlb_batch_begin_once

v2 (from RFC):
  * Rename misleading name
  * Abstract start batching function for listener_add/del

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20210812140933.226288-1-eperezma@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2021-09-04 09:07:45 -04:00

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/*
* vhost-vdpa.h
*
* Copyright(c) 2017-2018 Intel Corporation.
* Copyright(c) 2020 Red Hat, Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#ifndef HW_VIRTIO_VHOST_VDPA_H
#define HW_VIRTIO_VHOST_VDPA_H
#include "hw/virtio/virtio.h"
typedef struct VhostVDPAHostNotifier {
MemoryRegion mr;
void *addr;
} VhostVDPAHostNotifier;
typedef struct vhost_vdpa {
int device_fd;
uint32_t msg_type;
bool iotlb_batch_begin_sent;
MemoryListener listener;
struct vhost_dev *dev;
VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
} VhostVDPA;
#endif