From mboxrd@z Thu Jan 1 00:00:00 1970 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 4E1B9C43334 for ; Thu, 14 Jul 2022 16:44:32 +0000 (UTC) Received: from localhost ([::1]:59940 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oC1x1-0002dQ-Ek for qemu-devel@archiver.kernel.org; Thu, 14 Jul 2022 12:44:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36930) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oC1ld-0007tW-5G for qemu-devel@nongnu.org; Thu, 14 Jul 2022 12:32:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:30856) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oC1lY-0003Os-T2 for qemu-devel@nongnu.org; Thu, 14 Jul 2022 12:32:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657816360; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PT3ZCHXgCKzAyfUN6ryjGy3MEKB5gfGh4MtecdClGRc=; b=QIiDArYM9f07bO5cKX0UWNx6hQ8fQLaQ7rooV+ENq6YC4KvClNV/2gWs3H4f5ga5Y65Jm6 2acL01r0iaVkF2W7YY+C7tk5J/sA8dvOAEAlu8tvacHvzHjuxG5aORIH8XB8TyTbsuNge5 tcjsQc1nW6nUpD3jXWzorN8k/v5EKN4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-3-GFw_PCplOiG9vt-UQLUE2w-1; Thu, 14 Jul 2022 12:32:34 -0400 X-MC-Unique: GFw_PCplOiG9vt-UQLUE2w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 84268802D2C; Thu, 14 Jul 2022 16:32:33 +0000 (UTC) Received: from eperezma.remote.csb (unknown [10.39.192.102]) by smtp.corp.redhat.com (Postfix) with ESMTP id 58B001121314; Thu, 14 Jul 2022 16:32:30 +0000 (UTC) From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= To: qemu-devel@nongnu.org Cc: Gautam Dawar , Paolo Bonzini , "Michael S. Tsirkin" , Stefano Garzarella , Eric Blake , Zhu Lingshan , Stefan Hajnoczi , Markus Armbruster , Cornelia Huck , Parav Pandit , Laurent Vivier , Liuxiangdong , Eli Cohen , Cindy Lu , Harpreet Singh Anand , Jason Wang , "Gonglei (Arei)" Subject: [PATCH v2 12/19] vhost: add vhost_svq_poll Date: Thu, 14 Jul 2022 18:31:43 +0200 Message-Id: <20220714163150.2536327-13-eperezma@redhat.com> In-Reply-To: <20220714163150.2536327-1-eperezma@redhat.com> References: <20220714163150.2536327-1-eperezma@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=eperezma@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" It allows the Shadow Control VirtQueue to wait for the device to use the available buffers. Signed-off-by: Eugenio Pérez --- hw/virtio/vhost-shadow-virtqueue.h | 1 + hw/virtio/vhost-shadow-virtqueue.c | 22 ++++++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h index 1692541cbb..b5c6e3b3b4 100644 --- a/hw/virtio/vhost-shadow-virtqueue.h +++ b/hw/virtio/vhost-shadow-virtqueue.h @@ -89,6 +89,7 @@ void vhost_svq_push_elem(VhostShadowVirtqueue *svq, const SVQElement *elem, int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg, size_t out_num, const struct iovec *in_sg, size_t in_num, SVQElement *elem); +size_t vhost_svq_poll(VhostShadowVirtqueue *svq); void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd); void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd); diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c index 5244896358..31a267f721 100644 --- a/hw/virtio/vhost-shadow-virtqueue.c +++ b/hw/virtio/vhost-shadow-virtqueue.c @@ -486,6 +486,28 @@ static void vhost_svq_flush(VhostShadowVirtqueue *svq, } while (!vhost_svq_enable_notification(svq)); } +/** + * Poll the SVQ for one device used buffer. + * + * This function race with main event loop SVQ polling, so extra + * synchronization is needed. + * + * Return the length written by the device. + */ +size_t vhost_svq_poll(VhostShadowVirtqueue *svq) +{ + do { + uint32_t len; + SVQElement *elem = vhost_svq_get_buf(svq, &len); + if (elem) { + return len; + } + + /* Make sure we read new used_idx */ + smp_rmb(); + } while (true); +} + /** * Forward used buffers. * -- 2.31.1