From patchwork Fri Jan 19 13:57:48 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 13523815 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.gnu.org (lists.gnu.org [209.51.188.17]) (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 268C1C4725D for ; Fri, 19 Jan 2024 14:01:25 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rQpOI-0004pJ-36; Fri, 19 Jan 2024 08:58:38 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rQpOF-0004bu-5R for qemu-devel@nongnu.org; Fri, 19 Jan 2024 08:58:35 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rQpOC-0000cQ-SG for qemu-devel@nongnu.org; Fri, 19 Jan 2024 08:58:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705672711; 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=U7t+48tpry5FxJ8YbbmZC6mHpaAUgCVAoEt9nom/U1A=; b=TZ5eWUUMuc5rA5hecor8cgA/qqez65eUZYXVpjG4at14vl7EJzzZI19j5bK4SCIEQJWPgp CqAJveB3BMqV2/cquxZIbI4CUtMDyhe48QITxL6aSPwkfZEGWWEr6GW9UCrXy6xF5+6t0z GQ/sB6U1C9ese3ed1IhemG9IY8DzPO8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-458-zTJa3cbvOqiF8fMNTfZ45g-1; Fri, 19 Jan 2024 08:58:28 -0500 X-MC-Unique: zTJa3cbvOqiF8fMNTfZ45g-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4E178101A526; Fri, 19 Jan 2024 13:58:28 +0000 (UTC) Received: from localhost (unknown [10.39.195.31]) by smtp.corp.redhat.com (Postfix) with ESMTP id 77D39492BC6; Fri, 19 Jan 2024 13:58:27 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Stefan Hajnoczi , Thomas Huth , Hanna Reitz , =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= , qemu-block@nongnu.org, "Michael S. Tsirkin" , Kevin Wolf , Paolo Bonzini , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= Subject: [PATCH 6/6] virtio-blk: always set ioeventfd during startup Date: Fri, 19 Jan 2024 08:57:48 -0500 Message-ID: <20240119135748.270944-7-stefanha@redhat.com> In-Reply-To: <20240119135748.270944-1-stefanha@redhat.com> References: <20240119135748.270944-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@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_H3=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=unavailable 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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 --- 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 */ /* 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(vdev, i); - AioContext *ctx = s->vq_aio_context[i]; + for (i = 0; i < nvqs; i++) { + VirtQueue *vq = virtio_get_queue(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)); + /* Kick right away to begin processing requests already in vring */ + event_notifier_set(virtio_queue_get_host_notifier(vq)); + if (!blk_in_drain(s->conf.conf.blk)) { virtio_queue_aio_attach_host_notifier(vq, ctx); } }