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bh=8S/6JmKhF1sJKzjwL9n1KQwB67QmH+PBjRC6YVJgQIk=; b=O8YJzDOIZNLuq9Mdj4XzsD4c/k9wrOSC/ClVIVXeceBNx0eJVXx6wFIT9vlC5eAQ/OEmez ouGnZzL+Hsyz/RfodBcachKwr8xQDM+GeL7LNd3KGEqYb6a07d+x6W9/1r9yyjjRMSUWj8 hfa2ZEFWAdlBKBm3ybYQitjYfeP0J7o= X-MC-Unique: HC7_So04N7qJ8bJyOMWNZw-1 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org Subject: [PULL 13/14] virtio-blk: always set ioeventfd during startup Date: Fri, 19 Jan 2024 19:13:26 +0100 Message-ID: <20240119181327.236745-14-kwolf@redhat.com> In-Reply-To: <20240119181327.236745-1-kwolf@redhat.com> References: <20240119181327.236745-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -45 X-Spam_score: -4.6 X-Spam_bar: ---- X-Spam_report: (-4.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.519, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1705688125869100003 Content-Type: text/plain; charset="utf-8" From: Stefan Hajnoczi When starting ioeventfd it is common practice to set the event notifier so that the ioeventfd handler is triggered to run immediately. There may be no requests waiting to be processed, but the idea is that if a request snuck in then we guarantee that it will be detected. One scenario where self-triggering the ioeventfd is necessary is when virtio_blk_handle_output() is called from a vCPU thread before the VIRTIO Device Status transitions to DRIVER_OK. In that case we need to self-trigger the ioeventfd so that the kick handled by the vCPU thread causes the vq AioContext thread to take over handling the request(s). Fixes: b6948ab01df0 ("virtio-blk: add iothread-vq-mapping parameter") Reported-by: Kevin Wolf Signed-off-by: Stefan Hajnoczi Message-ID: <20240119135748.270944-7-stefanha@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- hw/block/virtio-blk.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 73248d15c8..227d83569f 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -1809,14 +1809,14 @@ static int virtio_blk_start_ioeventfd(VirtIODevice = *vdev) smp_wmb(); /* paired with aio_notify_accept() on the read side */ =20 /* Get this show started by hooking up our callbacks */ - if (!blk_in_drain(s->conf.conf.blk)) { - for (i =3D 0; i < nvqs; i++) { - VirtQueue *vq =3D virtio_get_queue(vdev, i); - AioContext *ctx =3D s->vq_aio_context[i]; + for (i =3D 0; i < nvqs; i++) { + VirtQueue *vq =3D virtio_get_queue(vdev, i); + AioContext *ctx =3D s->vq_aio_context[i]; =20 - /* Kick right away to begin processing requests already in vri= ng */ - event_notifier_set(virtio_queue_get_host_notifier(vq)); + /* Kick right away to begin processing requests already in vring */ + event_notifier_set(virtio_queue_get_host_notifier(vq)); =20 + if (!blk_in_drain(s->conf.conf.blk)) { virtio_queue_aio_attach_host_notifier(vq, ctx); } } --=20 2.43.0