From patchwork Fri Nov 20 18:50:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eugenio Perez Martin X-Patchwork-Id: 11921975 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D909DC63777 for ; Fri, 20 Nov 2020 18:56:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD9E824178 for ; Fri, 20 Nov 2020 18:56:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eAD5dJsm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732177AbgKTSzh (ORCPT ); Fri, 20 Nov 2020 13:55:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:36636 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732154AbgKTSzh (ORCPT ); Fri, 20 Nov 2020 13:55:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605898536; 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=XrOQ1s9JEtCDaxgd6vNOOY/KU2hMoYwe0eOTlPEs1LA=; b=eAD5dJsmR9nKwDQGhn4BIZD8VHoe0lrwwc1qBWAiaYSJl6w96SGRTt+flRpDWr91aCjclh 0PKYjUZA6xUtMK/yzgPw9+KY9sBMnBjZvjZeuxtF5onHC8b8OQ0+dKeodnJCi/ryzzJjrm ZGaMBV0RgL3x2EVw9xGG1EgugNdz9Yk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-539-3a8sTKaMN8eKwFoqmbXgCw-1; Fri, 20 Nov 2020 13:55:33 -0500 X-MC-Unique: 3a8sTKaMN8eKwFoqmbXgCw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AF8875B365; Fri, 20 Nov 2020 18:55:30 +0000 (UTC) Received: from eperezma.remote.csb (ovpn-112-88.ams2.redhat.com [10.36.112.88]) by smtp.corp.redhat.com (Postfix) with ESMTP id 798045C1D5; Fri, 20 Nov 2020 18:55:21 +0000 (UTC) From: =?utf-8?q?Eugenio_P=C3=A9rez?= To: qemu-devel@nongnu.org Cc: Lars Ganrot , virtualization@lists.linux-foundation.org, Salil Mehta , "Michael S. Tsirkin" , Liran Alon , Rob Miller , Max Gurtovoy , Alex Barba , Stefan Hajnoczi , Jim Harford , Jason Wang , Harpreet Singh Anand , Christophe Fontaine , vm , Daniel Daly , Michael Lilja , Stefano Garzarella , Nitin Shrivastav , Lee Ballard , Dmytro Kazantsev , Juan Quintela , kvm@vger.kernel.org, Howard Cai , Xiao W Wang , Sean Mooney , Parav Pandit , Eli Cohen , Siwei Liu , Stephen Finucane Subject: [RFC PATCH 18/27] vhost: add vhost_vring_poll_rcu Date: Fri, 20 Nov 2020 19:50:56 +0100 Message-Id: <20201120185105.279030-19-eperezma@redhat.com> In-Reply-To: <20201120185105.279030-1-eperezma@redhat.com> References: <20201120185105.279030-1-eperezma@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Signed-off-by: Eugenio Pérez --- hw/virtio/vhost-sw-lm-ring.h | 2 ++ hw/virtio/vhost-sw-lm-ring.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/hw/virtio/vhost-sw-lm-ring.h b/hw/virtio/vhost-sw-lm-ring.h index c537500d9e..03257d60c1 100644 --- a/hw/virtio/vhost-sw-lm-ring.h +++ b/hw/virtio/vhost-sw-lm-ring.h @@ -22,6 +22,8 @@ int vhost_vring_add(VhostShadowVirtqueue *vq, VirtQueueElement *elem); /* Called within rcu_read_lock(). */ void vhost_vring_set_notification_rcu(VhostShadowVirtqueue *vq, bool enable); +/* Called within rcu_read_lock(). */ +bool vhost_vring_poll_rcu(VhostShadowVirtqueue *vq); void vhost_vring_write_addr(const VhostShadowVirtqueue *vq, struct vhost_vring_addr *addr); diff --git a/hw/virtio/vhost-sw-lm-ring.c b/hw/virtio/vhost-sw-lm-ring.c index c3244c550e..3652889d8e 100644 --- a/hw/virtio/vhost-sw-lm-ring.c +++ b/hw/virtio/vhost-sw-lm-ring.c @@ -34,6 +34,12 @@ typedef struct VhostShadowVirtqueue { /* Next free descriptor */ uint16_t free_head; + /* Last seen used idx */ + uint16_t shadow_used_idx; + + /* Next head to consume from device */ + uint16_t used_idx; + /* Cache for exposed notification flag */ bool notification; @@ -83,6 +89,18 @@ void vhost_vring_set_notification_rcu(VhostShadowVirtqueue *vq, bool enable) smp_mb(); } +bool vhost_vring_poll_rcu(VhostShadowVirtqueue *vq) +{ + if (vq->used_idx != vq->shadow_used_idx) { + return true; + } + + smp_rmb(); + vq->shadow_used_idx = virtio_tswap16(vq->vdev, vq->vring.used->idx); + + return vq->used_idx != vq->shadow_used_idx; +} + static void vhost_vring_write_descs(VhostShadowVirtqueue *vq, const struct iovec *iovec, size_t num, bool more_descs, bool write)