From patchwork Mon Feb 4 20:18:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nitesh Narayan Lal X-Patchwork-Id: 10796539 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D2701922 for ; Mon, 4 Feb 2019 20:20:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C25062C0D0 for ; Mon, 4 Feb 2019 20:20:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C033B2B651; Mon, 4 Feb 2019 20:20:24 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 25E3D2B651 for ; Mon, 4 Feb 2019 20:20:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728239AbfBDUT5 (ORCPT ); Mon, 4 Feb 2019 15:19:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47246 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728094AbfBDUT4 (ORCPT ); Mon, 4 Feb 2019 15:19:56 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 376CF5D61C; Mon, 4 Feb 2019 20:19:56 +0000 (UTC) Received: from virtlab420.virt.lab.eng.bos.redhat.com (virtlab420.virt.lab.eng.bos.redhat.com [10.19.152.148]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2E4E175C79; Mon, 4 Feb 2019 20:19:48 +0000 (UTC) From: Nitesh Narayan Lal To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, lcapitulino@redhat.com, pagupta@redhat.com, wei.w.wang@intel.com, yang.zhang.wz@gmail.com, riel@surriel.com, david@redhat.com, mst@redhat.com, dodgen@google.com, konrad.wilk@oracle.com, dhildenb@redhat.com, aarcange@redhat.com Subject: [RFC][Patch v8 5/7] virtio: Enables to add a single descriptor to the host Date: Mon, 4 Feb 2019 15:18:52 -0500 Message-Id: <20190204201854.2328-6-nitesh@redhat.com> In-Reply-To: <20190204201854.2328-1-nitesh@redhat.com> References: <20190204201854.2328-1-nitesh@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Mon, 04 Feb 2019 20:19:56 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch enables the caller to expose a single buffers to the other end using vring descriptor. It also allows the caller to perform this action in synchornous manner by using virtqueue_kick_sync. Signed-off-by: Nitesh Narayan Lal --- drivers/virtio/virtio_ring.c | 72 ++++++++++++++++++++++++++++++++++++ include/linux/virtio.h | 4 ++ 2 files changed, 76 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index cd7e755484e3..93c161ac6a28 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -1695,6 +1695,52 @@ static inline int virtqueue_add(struct virtqueue *_vq, out_sgs, in_sgs, data, ctx, gfp); } +/** + * virtqueue_add_desc - add a buffer to a chain using a vring desc + * @vq: the struct virtqueue we're talking about. + * @addr: address of the buffer to add. + * @len: length of the buffer. + * @in: set if the buffer is for the device to write. + * + * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO). + */ +int virtqueue_add_desc(struct virtqueue *_vq, u64 addr, u32 len, int in) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + struct vring_desc *desc = vq->split.vring.desc; + u16 flags = in ? VRING_DESC_F_WRITE : 0; + unsigned int i; + void *data = (void *)addr; + int avail_idx; + + /* Sanity check */ + if (!_vq) + return -EINVAL; + + START_USE(vq); + if (unlikely(vq->broken)) { + END_USE(vq); + return -EIO; + } + + i = vq->free_head; + flags &= ~VRING_DESC_F_NEXT; + desc[i].flags = cpu_to_virtio16(_vq->vdev, flags); + desc[i].addr = cpu_to_virtio64(_vq->vdev, addr); + desc[i].len = cpu_to_virtio32(_vq->vdev, len); + + vq->vq.num_free--; + vq->free_head = virtio16_to_cpu(_vq->vdev, desc[i].next); + vq->split.desc_state[i].data = data; + vq->split.avail_idx_shadow = 1; + avail_idx = vq->split.avail_idx_shadow; + vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev, avail_idx); + vq->num_added = 1; + END_USE(vq); + return 0; +} +EXPORT_SYMBOL_GPL(virtqueue_add_desc); + /** * virtqueue_add_sgs - expose buffers to other end * @vq: the struct virtqueue we're talking about. @@ -1842,6 +1888,32 @@ bool virtqueue_notify(struct virtqueue *_vq) } EXPORT_SYMBOL_GPL(virtqueue_notify); +/** + * virtqueue_kick_sync - update after add_buf and busy wait till update is done + * @vq: the struct virtqueue + * + * After one or more virtqueue_add_* calls, invoke this to kick + * the other side. Busy wait till the other side is done with the update. + * + * Caller must ensure we don't call this with other virtqueue + * operations at the same time (except where noted). + * + * Returns false if kick failed, otherwise true. + */ +bool virtqueue_kick_sync(struct virtqueue *vq) +{ + u32 len; + + if (likely(virtqueue_kick(vq))) { + while (!virtqueue_get_buf(vq, &len) && + !virtqueue_is_broken(vq)) + cpu_relax(); + return true; + } + return false; +} +EXPORT_SYMBOL_GPL(virtqueue_kick_sync); + /** * virtqueue_kick - update after add_buf * @vq: the struct virtqueue diff --git a/include/linux/virtio.h b/include/linux/virtio.h index fa1b5da2804e..58943a3a0e8d 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -57,6 +57,10 @@ int virtqueue_add_sgs(struct virtqueue *vq, unsigned int in_sgs, void *data, gfp_t gfp); +/* A desc with this init id is treated as an invalid desc */ +int virtqueue_add_desc(struct virtqueue *_vq, u64 addr, u32 len, int in); + +bool virtqueue_kick_sync(struct virtqueue *vq); bool virtqueue_kick(struct virtqueue *vq);