From patchwork Wed Apr 19 17:28:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13217203 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EFA95C77B73 for ; Wed, 19 Apr 2023 17:39:13 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.523675.814013 (Exim 4.92) (envelope-from ) id 1ppBlm-0000UE-Pc; Wed, 19 Apr 2023 17:39:02 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 523675.814013; Wed, 19 Apr 2023 17:39:02 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ppBlm-0000Si-5e; Wed, 19 Apr 2023 17:39:02 +0000 Received: by outflank-mailman (input) for mailman id 523675; Wed, 19 Apr 2023 17:38:59 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ppBcW-0001ia-0d for xen-devel@lists.xenproject.org; Wed, 19 Apr 2023 17:29:28 +0000 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id bb7d62a9-ded7-11ed-b21f-6b7b168915f2; Wed, 19 Apr 2023 19:29:27 +0200 (CEST) Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-457-UORK3zzVOxmLu7977uaTMQ-1; Wed, 19 Apr 2023 13:29:22 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 59D9D1C189A4; Wed, 19 Apr 2023 17:29:21 +0000 (UTC) Received: from localhost (unknown [10.39.192.234]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8045B40C2064; Wed, 19 Apr 2023 17:29:20 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: bb7d62a9-ded7-11ed-b21f-6b7b168915f2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681925366; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Qs0Wu6hxc7j58DwPPRdDhx+qIxo2MCSBXMmfJ14jr7A=; b=P81Hbad2MkrxYTfi71uOxxkGaggxm+9W6bTi5GM2BTkPDcPFnK7pF6YXAlQOQkOq/8nV1O hWV0a02+t5ibJI9zvKkiL8RyS6ToCmoM4vuje/hz+FkZktCEZmssTifAfPzGl6DH0z5Wb/ GjxSdH06n467P6qYOIzjoaC5c7SG0UE= X-MC-Unique: UORK3zzVOxmLu7977uaTMQ-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Stefano Stabellini , Marcel Apfelbaum , Fam Zheng , Stefan Hajnoczi , Julia Suvorova , Hanna Reitz , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , Paolo Bonzini , Coiby Xu , Paul Durrant , Ronnie Sahlberg , Eduardo Habkost , Juan Quintela , "Michael S. Tsirkin" , Stefano Garzarella , Anthony Perard , Kevin Wolf , "Richard W.M. Jones" , Richard Henderson , xen-devel@lists.xenproject.org, qemu-block@nongnu.org, "Dr. David Alan Gilbert" , =?utf-8?q?Philippe_Mathieu-?= =?utf-8?q?Daud=C3=A9?= , Peter Lieven , eesposit@redhat.com, Aarushi Mehta , Stefan Weil , Xie Yongji , David Woodhouse Subject: [PATCH v2 16/16] virtio: make it possible to detach host notifier from any thread Date: Wed, 19 Apr 2023 13:28:17 -0400 Message-Id: <20230419172817.272758-17-stefanha@redhat.com> In-Reply-To: <20230419172817.272758-1-stefanha@redhat.com> References: <20230419172817.272758-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 virtio_queue_aio_detach_host_notifier() does two things: 1. It removes the fd handler from the event loop. 2. It processes the virtqueue one last time. The first step can be peformed by any thread and without taking the AioContext lock. The second step may need the AioContext lock (depending on the device implementation) and runs in the thread where request processing takes place. virtio-blk and virtio-scsi therefore call virtio_queue_aio_detach_host_notifier() from a BH that is scheduled in AioContext Scheduling a BH is undesirable for .drained_begin() functions. The next patch will introduce a .drained_begin() function that needs to call virtio_queue_aio_detach_host_notifier(). Move the virtqueue processing out to the callers of virtio_queue_aio_detach_host_notifier() so that the function can be called from any thread. This is in preparation for the next patch. Signed-off-by: Stefan Hajnoczi --- hw/block/dataplane/virtio-blk.c | 2 ++ hw/scsi/virtio-scsi-dataplane.c | 9 +++++++++ 2 files changed, 11 insertions(+) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index b28d81737e..bd7cc6e76b 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -286,8 +286,10 @@ static void virtio_blk_data_plane_stop_bh(void *opaque) for (i = 0; i < s->conf->num_queues; i++) { VirtQueue *vq = virtio_get_queue(s->vdev, i); + EventNotifier *host_notifier = virtio_queue_get_host_notifier(vq); virtio_queue_aio_detach_host_notifier(vq, s->ctx); + virtio_queue_host_notifier_read(host_notifier); } } diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c index 20bb91766e..81643445ed 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -71,12 +71,21 @@ static void virtio_scsi_dataplane_stop_bh(void *opaque) { VirtIOSCSI *s = opaque; VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s); + EventNotifier *host_notifier; int i; virtio_queue_aio_detach_host_notifier(vs->ctrl_vq, s->ctx); + host_notifier = virtio_queue_get_host_notifier(vs->ctrl_vq); + virtio_queue_host_notifier_read(host_notifier); + virtio_queue_aio_detach_host_notifier(vs->event_vq, s->ctx); + host_notifier = virtio_queue_get_host_notifier(vs->event_vq); + virtio_queue_host_notifier_read(host_notifier); + for (i = 0; i < vs->conf.num_queues; i++) { virtio_queue_aio_detach_host_notifier(vs->cmd_vqs[i], s->ctx); + host_notifier = virtio_queue_get_host_notifier(vs->cmd_vqs[i]); + virtio_queue_host_notifier_read(host_notifier); } }