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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 844F0C433F5 for ; Sat, 7 May 2022 07:20:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1445816AbiEGHY3 (ORCPT ); Sat, 7 May 2022 03:24:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1445980AbiEGHYQ (ORCPT ); Sat, 7 May 2022 03:24:16 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id A8F7FDFD8 for ; Sat, 7 May 2022 00:20:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651908024; 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=7HQgO42DhiTroM5cVrJbp9LPKhZMQuD4duQmjIjsdyU=; b=DvItww/5utbbFxSVCdsW5eYoPLLtfb2y3eKJYyZhBjypmvYDudhc3/5dX6/dhXjy4aQaqh tJ33ywHbr75yWBOz/t5Bww4MdNHWHA+4G0a+3f9OeOuoJHjgtXzjv+CryiVr2bAT7cpbR9 Cjny3PjSCoGMcVbsxbmhsv+BO5HMry8= 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-595-CnFIrtpOPsaGTmhdPQbSFw-1; Sat, 07 May 2022 03:20:23 -0400 X-MC-Unique: CnFIrtpOPsaGTmhdPQbSFw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 214C9101AA44; Sat, 7 May 2022 07:20:23 +0000 (UTC) Received: from localhost.localdomain (ovpn-13-216.pek2.redhat.com [10.72.13.216]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9180940D2971; Sat, 7 May 2022 07:20:17 +0000 (UTC) From: Jason Wang To: jasowang@redhat.com, mst@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, peterz@infradead.org, paulmck@kernel.org, maz@kernel.org, pasic@linux.ibm.com, cohuck@redhat.com, eperezma@redhat.com, lulu@redhat.com, sgarzare@redhat.com, xuanzhuo@linux.alibaba.com Subject: [PATCH V4 3/9] virtio: introduce config op to synchronize vring callbacks Date: Sat, 7 May 2022 15:19:48 +0800 Message-Id: <20220507071954.14455-4-jasowang@redhat.com> In-Reply-To: <20220507071954.14455-1-jasowang@redhat.com> References: <20220507071954.14455-1-jasowang@redhat.com> MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch introduces new virtio config op to vring callbacks. Transport specific method is required to make sure the write before this function is visible to the vring_interrupt() that is called after the return of this function. For the transport that doesn't provide synchronize_vqs(), use synchornize_rcu() which synchronize with IRQ implicitly as a fallback. Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: "Paul E. McKenney" Cc: Marc Zyngier Cc: Halil Pasic Cc: Cornelia Huck Signed-off-by: Jason Wang --- include/linux/virtio_config.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index b341dd62aa4d..d8a2340f928e 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -57,6 +57,11 @@ struct virtio_shm_region { * include a NULL entry for vqs unused by driver * Returns 0 on success or error status * @del_vqs: free virtqueues found by find_vqs(). + * @synchronize_cbs: synchronize with the virtqueue callbacks (optional) + * The function guarantees that all memory operations on the + * queue before it are visible to the vring_interrupt() that is + * called after it. + * vdev: the virtio_device * @get_features: get the array of feature bits for this device. * vdev: the virtio_device * Returns the first 64 feature bits (all we currently need). @@ -89,6 +94,7 @@ struct virtio_config_ops { const char * const names[], const bool *ctx, struct irq_affinity *desc); void (*del_vqs)(struct virtio_device *); + void (*synchronize_cbs)(struct virtio_device *); u64 (*get_features)(struct virtio_device *vdev); int (*finalize_features)(struct virtio_device *vdev); const char *(*bus_name)(struct virtio_device *vdev); @@ -217,6 +223,25 @@ int virtio_find_vqs_ctx(struct virtio_device *vdev, unsigned nvqs, desc); } +/** + * virtio_synchronize_cbs - synchronize with virtqueue callbacks + * @vdev: the device + */ +static inline +void virtio_synchronize_cbs(struct virtio_device *dev) +{ + if (dev->config->synchronize_cbs) { + dev->config->synchronize_cbs(dev); + } else { + /* + * A best effort fallback to synchronize with + * interrupts, preemption and softirq. See comment + * above synchronize_rcu(). + */ + synchronize_rcu(); + } +} + /** * virtio_device_ready - enable vq use in probe function * @vdev: the device -- 2.25.1