qemu-kvm/kvm-virtio-blk-rename-dataplane-create-destroy-functions.patch

From 71257c2f320f1511de1e275779cf4b90effc1f02 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Fri, 19 Jan 2024 08:57:44 -0500
Subject: [PATCH 15/22] virtio-blk: rename dataplane create/destroy functions

RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
RH-MergeRequest: 219: virtio-blk: add iothread-vq-mapping parameter
RH-Jira: RHEL-17369 RHEL-20764 RHEL-7356
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
RH-Commit: [11/17] 60e7016d5f3e4e9e89945578279b12f812f85ddf (stefanha/centos-stream-qemu-kvm)

virtio_blk_data_plane_create() and virtio_blk_data_plane_destroy() are
actually about s->vq_aio_context[] rather than managing
dataplane-specific state.

As a prerequisite to using s->vq_aio_context[] in all code paths (even
when dataplane is not used), rename these functions to reflect that they
just manage s->vq_aio_context and call them regardless of whether or not
dataplane is in use.

Note that virtio-blk supports running with -device
virtio-blk-pci,ioevent=off where the vCPU thread enters the device
emulation code. In this mode ioeventfd is not used for virtqueue
processing. However, we still want to initialize s->vq_aio_context[] to
qemu_aio_context in that case since I/O completion callbacks will be
invoked in the main loop thread.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20240119135748.270944-3-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 57bc2658935778d1ae0edbcd4402763da8c7bae2)
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/block/virtio-blk.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index cb623069f8..4d6f9377c6 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1608,7 +1608,7 @@ apply_vq_mapping(IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
         IOThread *iothread = iothread_by_id(node->value->iothread);
         AioContext *ctx = iothread_get_aio_context(iothread);
 
-        /* Released in virtio_blk_data_plane_destroy() */
+        /* Released in virtio_blk_vq_aio_context_cleanup() */
         object_ref(OBJECT(iothread));
 
         if (node->value->vqs) {
@@ -1631,7 +1631,7 @@ apply_vq_mapping(IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
 }
 
 /* Context: BQL held */
-static bool virtio_blk_data_plane_create(VirtIOBlock *s, Error **errp)
+static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
     VirtIOBlkConf *conf = &s->conf;
@@ -1659,11 +1659,6 @@ static bool virtio_blk_data_plane_create(VirtIOBlock *s, Error **errp)
             return false;
         }
     }
-    /* Don't try if transport does not support notifiers. */
-    if (!virtio_device_ioeventfd_enabled(vdev)) {
-        s->dataplane_disabled = true;
-        return false;
-    }
 
     s->vq_aio_context = g_new(AioContext *, conf->num_queues);
 
@@ -1676,7 +1671,7 @@ static bool virtio_blk_data_plane_create(VirtIOBlock *s, Error **errp)
             s->vq_aio_context[i] = ctx;
         }
 
-        /* Released in virtio_blk_data_plane_destroy() */
+        /* Released in virtio_blk_vq_aio_context_cleanup() */
         object_ref(OBJECT(conf->iothread));
     } else {
         AioContext *ctx = qemu_get_aio_context();
@@ -1689,7 +1684,7 @@ static bool virtio_blk_data_plane_create(VirtIOBlock *s, Error **errp)
 }
 
 /* Context: BQL held */
-static void virtio_blk_data_plane_destroy(VirtIOBlock *s)
+static void virtio_blk_vq_aio_context_cleanup(VirtIOBlock *s)
 {
     VirtIOBlkConf *conf = &s->conf;
 
@@ -2015,7 +2010,13 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
         virtio_add_queue(vdev, conf->queue_size, virtio_blk_handle_output);
     }
     qemu_coroutine_inc_pool_size(conf->num_queues * conf->queue_size / 2);
-    virtio_blk_data_plane_create(s, &err);
+
+    /* Don't start dataplane if transport does not support notifiers. */
+    if (!virtio_device_ioeventfd_enabled(vdev)) {
+        s->dataplane_disabled = true;
+    }
+
+    virtio_blk_vq_aio_context_init(s, &err);
     if (err != NULL) {
         error_propagate(errp, err);
         for (i = 0; i < conf->num_queues; i++) {
@@ -2052,7 +2053,7 @@ static void virtio_blk_device_unrealize(DeviceState *dev)
 
     blk_drain(s->blk);
     del_boot_device_lchs(dev, "/disk@0,0");
-    virtio_blk_data_plane_destroy(s);
+    virtio_blk_vq_aio_context_cleanup(s);
     for (i = 0; i < conf->num_queues; i++) {
         virtio_del_queue(vdev, i);
     }
-- 
2.39.3