virtio-blk: move dataplane code into virtio-blk.c

The dataplane code used to be significantly different from the
non-dataplane code and therefore had a separate source file.

Over time the difference has gotten smaller because the I/O code paths
were unified. Nowadays the distinction between the VirtIOBlock and
VirtIOBlockDataPlane structs is more of an inconvenience that hinders
code simplification.

Move hw/block/dataplane/virtio-blk.c into hw/block/virtio-blk.c, merging
VirtIOBlockDataPlane's fields into VirtIOBlock.

hw/block/virtio-blk.c used VirtIOBlock->dataplane to check if
virtio_blk_data_plane_create() was successful. This is not necessary
because ->dataplane_started and ->dataplane_disabled can be used
instead. This patch makes those changes in order to drop
VirtIOBlock->dataplane.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240119135748.270944-2-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

5 files changed, 0 insertions, 445 deletions

diff --git a/hw/block/dataplane/meson.build b/hw/block/dataplane/meson.build
index 025b3b061b..11a5eba2f4 100644
--- a/hw/block/dataplane/meson.build
+++ b/hw/block/dataplane/meson.build
@@ -1,2 +1 @@
-system_ss.add(when: 'CONFIG_VIRTIO_BLK', if_true: files('virtio-blk.c'))
 specific_ss.add(when: 'CONFIG_XEN_BUS', if_true: files('xen-block.c'))
diff --git a/hw/block/dataplane/trace-events b/hw/block/dataplane/trace-events
deleted file mode 100644
index 38fc3e7507..0000000000
--- a/hw/block/dataplane/trace-events
+++ /dev/null
@@ -1,5 +0,0 @@
-# See docs/devel/tracing.rst for syntax documentation.
-
-# virtio-blk.c
-virtio_blk_data_plane_start(void *s) "dataplane %p"
-virtio_blk_data_plane_stop(void *s) "dataplane %p"
diff --git a/hw/block/dataplane/trace.h b/hw/block/dataplane/trace.h
deleted file mode 100644
index 240cc59834..0000000000
--- a/hw/block/dataplane/trace.h
+++ /dev/null
@@ -1 +0,0 @@
-#include "trace/trace-hw_block_dataplane.h"
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
deleted file mode 100644
index ba22732497..0000000000
--- a/hw/block/dataplane/virtio-blk.c
+++ /dev/null
@@ -1,404 +0,0 @@
-/*
- * Dedicated thread for virtio-blk I/O processing
- *
- * Copyright 2012 IBM, Corp.
- * Copyright 2012 Red Hat, Inc. and/or its affiliates
- *
- * Authors:
- *   Stefan Hajnoczi <stefanha@redhat.com>
- *
- * This work is licensed under the terms of the GNU GPL, version 2 or later.
- * See the COPYING file in the top-level directory.
- *
- */
-
-#include "qemu/osdep.h"
-#include "qapi/error.h"
-#include "trace.h"
-#include "qemu/iov.h"
-#include "qemu/main-loop.h"
-#include "qemu/thread.h"
-#include "qemu/error-report.h"
-#include "hw/virtio/virtio-blk.h"
-#include "virtio-blk.h"
-#include "block/aio.h"
-#include "hw/virtio/virtio-bus.h"
-#include "qom/object_interfaces.h"
-
-struct VirtIOBlockDataPlane {
-    bool starting;
-    bool stopping;
-
-    VirtIOBlkConf *conf;
-    VirtIODevice *vdev;
-
-    /*
-     * The AioContext for each virtqueue. The BlockDriverState will use the
-     * first element as its AioContext.
-     */
-    AioContext **vq_aio_context;
-};
-
-/* Raise an interrupt to signal guest, if necessary */
-void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq)
-{
-    virtio_notify_irqfd(s->vdev, vq);
-}
-
-/* Generate vq:AioContext mappings from a validated iothread-vq-mapping list */
-static void
-apply_vq_mapping(IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
-                 AioContext **vq_aio_context, uint16_t num_queues)
-{
-    IOThreadVirtQueueMappingList *node;
-    size_t num_iothreads = 0;
-    size_t cur_iothread = 0;
-
-    for (node = iothread_vq_mapping_list; node; node = node->next) {
-        num_iothreads++;
-    }
-
-    for (node = iothread_vq_mapping_list; node; node = node->next) {
-        IOThread *iothread = iothread_by_id(node->value->iothread);
-        AioContext *ctx = iothread_get_aio_context(iothread);
-
-        /* Released in virtio_blk_data_plane_destroy() */
-        object_ref(OBJECT(iothread));
-
-        if (node->value->vqs) {
-            uint16List *vq;
-
-            /* Explicit vq:IOThread assignment */
-            for (vq = node->value->vqs; vq; vq = vq->next) {
-                vq_aio_context[vq->value] = ctx;
-            }
-        } else {
-            /* Round-robin vq:IOThread assignment */
-            for (unsigned i = cur_iothread; i < num_queues;
-                 i += num_iothreads) {
-                vq_aio_context[i] = ctx;
-            }
-        }
-
-        cur_iothread++;
-    }
-}
-
-/* Context: BQL held */
-bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
-                                  VirtIOBlockDataPlane **dataplane,
-                                  Error **errp)
-{
-    VirtIOBlockDataPlane *s;
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
-
-    *dataplane = NULL;
-
-    if (conf->iothread || conf->iothread_vq_mapping_list) {
-        if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
-            error_setg(errp,
-                       "device is incompatible with iothread "
-                       "(transport does not support notifiers)");
-            return false;
-        }
-        if (!virtio_device_ioeventfd_enabled(vdev)) {
-            error_setg(errp, "ioeventfd is required for iothread");
-            return false;
-        }
-
-        /* If dataplane is (re-)enabled while the guest is running there could
-         * be block jobs that can conflict.
-         */
-        if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
-            error_prepend(errp, "cannot start virtio-blk dataplane: ");
-            return false;
-        }
-    }
-    /* Don't try if transport does not support notifiers. */
-    if (!virtio_device_ioeventfd_enabled(vdev)) {
-        return false;
-    }
-
-    s = g_new0(VirtIOBlockDataPlane, 1);
-    s->vdev = vdev;
-    s->conf = conf;
-    s->vq_aio_context = g_new(AioContext *, conf->num_queues);
-
-    if (conf->iothread_vq_mapping_list) {
-        apply_vq_mapping(conf->iothread_vq_mapping_list, s->vq_aio_context,
-                         conf->num_queues);
-    } else if (conf->iothread) {
-        AioContext *ctx = iothread_get_aio_context(conf->iothread);
-        for (unsigned i = 0; i < conf->num_queues; i++) {
-            s->vq_aio_context[i] = ctx;
-        }
-
-        /* Released in virtio_blk_data_plane_destroy() */
-        object_ref(OBJECT(conf->iothread));
-    } else {
-        AioContext *ctx = qemu_get_aio_context();
-        for (unsigned i = 0; i < conf->num_queues; i++) {
-            s->vq_aio_context[i] = ctx;
-        }
-    }
-
-    *dataplane = s;
-
-    return true;
-}
-
-/* Context: BQL held */
-void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
-{
-    VirtIOBlock *vblk;
-    VirtIOBlkConf *conf;
-
-    if (!s) {
-        return;
-    }
-
-    vblk = VIRTIO_BLK(s->vdev);
-    assert(!vblk->dataplane_started);
-    conf = s->conf;
-
-    if (conf->iothread_vq_mapping_list) {
-        IOThreadVirtQueueMappingList *node;
-
-        for (node = conf->iothread_vq_mapping_list; node; node = node->next) {
-            IOThread *iothread = iothread_by_id(node->value->iothread);
-            object_unref(OBJECT(iothread));
-        }
-    }
-
-    if (conf->iothread) {
-        object_unref(OBJECT(conf->iothread));
-    }
-
-    g_free(s->vq_aio_context);
-    g_free(s);
-}
-
-/* Context: BQL held */
-int virtio_blk_data_plane_start(VirtIODevice *vdev)
-{
-    VirtIOBlock *vblk = VIRTIO_BLK(vdev);
-    VirtIOBlockDataPlane *s = vblk->dataplane;
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vblk)));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
-    unsigned i;
-    unsigned nvqs = s->conf->num_queues;
-    Error *local_err = NULL;
-    int r;
-
-    if (vblk->dataplane_started || s->starting) {
-        return 0;
-    }
-
-    s->starting = true;
-
-    /* Set up guest notifier (irq) */
-    r = k->set_guest_notifiers(qbus->parent, nvqs, true);
-    if (r != 0) {
-        error_report("virtio-blk failed to set guest notifier (%d), "
-                     "ensure -accel kvm is set.", r);
-        goto fail_guest_notifiers;
-    }
-
-    /*
-     * Batch all the host notifiers in a single transaction to avoid
-     * quadratic time complexity in address_space_update_ioeventfds().
-     */
-    memory_region_transaction_begin();
-
-    /* Set up virtqueue notify */
-    for (i = 0; i < nvqs; i++) {
-        r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, true);
-        if (r != 0) {
-            int j = i;
-
-            fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
-            while (i--) {
-                virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
-            }
-
-            /*
-             * The transaction expects the ioeventfds to be open when it
-             * commits. Do it now, before the cleanup loop.
-             */
-            memory_region_transaction_commit();
-
-            while (j--) {
-                virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), j);
-            }
-            goto fail_host_notifiers;
-        }
-    }
-
-    memory_region_transaction_commit();
-
-    trace_virtio_blk_data_plane_start(s);
-
-    r = blk_set_aio_context(s->conf->conf.blk, s->vq_aio_context[0],
-                            &local_err);
-    if (r < 0) {
-        error_report_err(local_err);
-        goto fail_aio_context;
-    }
-
-    /*
-     * These fields must be visible to the IOThread when it processes the
-     * virtqueue, otherwise it will think dataplane has not started yet.
-     *
-     * Make sure ->dataplane_started is false when blk_set_aio_context() is
-     * called above so that draining does not cause the host notifier to be
-     * detached/attached prematurely.
-     */
-    s->starting = false;
-    vblk->dataplane_started = true;
-    smp_wmb(); /* paired with aio_notify_accept() on the read side */
-
-    /* Get this show started by hooking up our callbacks */
-    if (!blk_in_drain(s->conf->conf.blk)) {
-        for (i = 0; i < nvqs; i++) {
-            VirtQueue *vq = virtio_get_queue(s->vdev, i);
-            AioContext *ctx = s->vq_aio_context[i];
-
-            /* Kick right away to begin processing requests already in vring */
-            event_notifier_set(virtio_queue_get_host_notifier(vq));
-
-            virtio_queue_aio_attach_host_notifier(vq, ctx);
-        }
-    }
-    return 0;
-
-  fail_aio_context:
-    memory_region_transaction_begin();
-
-    for (i = 0; i < nvqs; i++) {
-        virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
-    }
-
-    memory_region_transaction_commit();
-
-    for (i = 0; i < nvqs; i++) {
-        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
-    }
-  fail_host_notifiers:
-    k->set_guest_notifiers(qbus->parent, nvqs, false);
-  fail_guest_notifiers:
-    vblk->dataplane_disabled = true;
-    s->starting = false;
-    return -ENOSYS;
-}
-
-/* Stop notifications for new requests from guest.
- *
- * Context: BH in IOThread
- */
-static void virtio_blk_data_plane_stop_vq_bh(void *opaque)
-{
-    VirtQueue *vq = opaque;
-    EventNotifier *host_notifier = virtio_queue_get_host_notifier(vq);
-
-    virtio_queue_aio_detach_host_notifier(vq, qemu_get_current_aio_context());
-
-    /*
-     * Test and clear notifier after disabling event, in case poll callback
-     * didn't have time to run.
-     */
-    virtio_queue_host_notifier_read(host_notifier);
-}
-
-/* Context: BQL held */
-void virtio_blk_data_plane_stop(VirtIODevice *vdev)
-{
-    VirtIOBlock *vblk = VIRTIO_BLK(vdev);
-    VirtIOBlockDataPlane *s = vblk->dataplane;
-    BusState *qbus = qdev_get_parent_bus(DEVICE(vblk));
-    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
-    unsigned i;
-    unsigned nvqs = s->conf->num_queues;
-
-    if (!vblk->dataplane_started || s->stopping) {
-        return;
-    }
-
-    /* Better luck next time. */
-    if (vblk->dataplane_disabled) {
-        vblk->dataplane_disabled = false;
-        vblk->dataplane_started = false;
-        return;
-    }
-    s->stopping = true;
-    trace_virtio_blk_data_plane_stop(s);
-
-    if (!blk_in_drain(s->conf->conf.blk)) {
-        for (i = 0; i < nvqs; i++) {
-            VirtQueue *vq = virtio_get_queue(s->vdev, i);
-            AioContext *ctx = s->vq_aio_context[i];
-
-            aio_wait_bh_oneshot(ctx, virtio_blk_data_plane_stop_vq_bh, vq);
-        }
-    }
-
-    /*
-     * Batch all the host notifiers in a single transaction to avoid
-     * quadratic time complexity in address_space_update_ioeventfds().
-     */
-    memory_region_transaction_begin();
-
-    for (i = 0; i < nvqs; i++) {
-        virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), i, false);
-    }
-
-    /*
-     * The transaction expects the ioeventfds to be open when it
-     * commits. Do it now, before the cleanup loop.
-     */
-    memory_region_transaction_commit();
-
-    for (i = 0; i < nvqs; i++) {
-        virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
-    }
-
-    /*
-     * Set ->dataplane_started to false before draining so that host notifiers
-     * are not detached/attached anymore.
-     */
-    vblk->dataplane_started = false;
-
-    /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
-    blk_drain(s->conf->conf.blk);
-
-    /*
-     * Try to switch bs back to the QEMU main loop. If other users keep the
-     * BlockBackend in the iothread, that's ok
-     */
-    blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
-
-    /* Clean up guest notifier (irq) */
-    k->set_guest_notifiers(qbus->parent, nvqs, false);
-
-    s->stopping = false;
-}
-
-void virtio_blk_data_plane_detach(VirtIOBlockDataPlane *s)
-{
-    VirtIODevice *vdev = VIRTIO_DEVICE(s->vdev);
-
-    for (uint16_t i = 0; i < s->conf->num_queues; i++) {
-        VirtQueue *vq = virtio_get_queue(vdev, i);
-        virtio_queue_aio_detach_host_notifier(vq, s->vq_aio_context[i]);
-    }
-}
-
-void virtio_blk_data_plane_attach(VirtIOBlockDataPlane *s)
-{
-    VirtIODevice *vdev = VIRTIO_DEVICE(s->vdev);
-
-    for (uint16_t i = 0; i < s->conf->num_queues; i++) {
-        VirtQueue *vq = virtio_get_queue(vdev, i);
-        virtio_queue_aio_attach_host_notifier(vq, s->vq_aio_context[i]);
-    }
-}
diff --git a/hw/block/dataplane/virtio-blk.h b/hw/block/dataplane/virtio-blk.h
deleted file mode 100644
index 1a806fe447..0000000000
--- a/hw/block/dataplane/virtio-blk.h
+++ /dev/null
@@ -1,34 +0,0 @@
-/*
- * Dedicated thread for virtio-blk I/O processing
- *
- * Copyright 2012 IBM, Corp.
- * Copyright 2012 Red Hat, Inc. and/or its affiliates
- *
- * Authors:
- *   Stefan Hajnoczi <stefanha@redhat.com>
- *
- * 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_DATAPLANE_VIRTIO_BLK_H
-#define HW_DATAPLANE_VIRTIO_BLK_H
-
-#include "hw/virtio/virtio.h"
-
-typedef struct VirtIOBlockDataPlane VirtIOBlockDataPlane;
-
-bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
-                                  VirtIOBlockDataPlane **dataplane,
-                                  Error **errp);
-void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
-void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq);
-
-int virtio_blk_data_plane_start(VirtIODevice *vdev);
-void virtio_blk_data_plane_stop(VirtIODevice *vdev);
-
-void virtio_blk_data_plane_detach(VirtIOBlockDataPlane *s);
-void virtio_blk_data_plane_attach(VirtIOBlockDataPlane *s);
-
-#endif /* HW_DATAPLANE_VIRTIO_BLK_H */