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 X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9CFBAC433E0 for ; Wed, 3 Jun 2020 07:58:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F0A2206C3 for ; Wed, 3 Jun 2020 07:58:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QT3wVAQs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726159AbgFCH6j (ORCPT ); Wed, 3 Jun 2020 03:58:39 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:49399 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725877AbgFCH6j (ORCPT ); Wed, 3 Jun 2020 03:58:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591171117; 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=6s4YwWjWSDJyEzvWoBd/i85+Sheo/GOp6+xMWZwy3wU=; b=QT3wVAQs1deiYlEdDOl+maeqWVWvd8K8p9GWd/M2I+2IyduK4stQuAw/8gsC1ByjW9qsPp 9kEatIOEFXOTySAzFXc0YTgSp1iSVRNz4AhGlsys4ontYDQBhwM+kOrr3M56XTV68kjyGG 6bejlrye06UW2xnGREAq4xKqQLVvSQw= 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-352-9RybUihZM9iS6EvrhrYauA-1; Wed, 03 Jun 2020 03:58:35 -0400 X-MC-Unique: 9RybUihZM9iS6EvrhrYauA-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 F08EE800685; Wed, 3 Jun 2020 07:58:33 +0000 (UTC) Received: from [10.72.12.214] (ovpn-12-214.pek2.redhat.com [10.72.12.214]) by smtp.corp.redhat.com (Postfix) with ESMTP id 582B95C221; Wed, 3 Jun 2020 07:58:28 +0000 (UTC) Subject: Re: [PATCH RFC 07/13] vhost: format-independent API for used buffers To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Cc: =?UTF-8?Q?Eugenio_P=c3=a9rez?= , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org References: <20200602130543.578420-1-mst@redhat.com> <20200602130543.578420-8-mst@redhat.com> From: Jason Wang Message-ID: <6d98f2cc-2084-cde0-c938-4ca01692adf9@redhat.com> Date: Wed, 3 Jun 2020 15:58:26 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200602130543.578420-8-mst@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/6/2 下午9:06, Michael S. Tsirkin wrote: > Add a new API that doesn't assume used ring, heads, etc. > For now, we keep the old APIs around to make it easier > to convert drivers. > > Signed-off-by: Michael S. Tsirkin > --- > drivers/vhost/vhost.c | 52 ++++++++++++++++++++++++++++++++++--------- > drivers/vhost/vhost.h | 17 +++++++++++++- > 2 files changed, 58 insertions(+), 11 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index b4a6e44d56a8..be822f0c9428 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -2292,13 +2292,12 @@ static int fetch_descs(struct vhost_virtqueue *vq) > * number of output then some number of input descriptors, it's actually two > * iovecs, but we pack them into one and note how many of each there were. > * > - * This function returns the descriptor number found, or vq->num (which is > - * never a valid descriptor number) if none was found. A negative code is > - * returned on error. */ > -int vhost_get_vq_desc(struct vhost_virtqueue *vq, > - struct iovec iov[], unsigned int iov_size, > - unsigned int *out_num, unsigned int *in_num, > - struct vhost_log *log, unsigned int *log_num) > + * This function returns a value > 0 if a descriptor was found, or 0 if none were found. > + * A negative code is returned on error. */ > +int vhost_get_avail_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf, > + struct iovec iov[], unsigned int iov_size, > + unsigned int *out_num, unsigned int *in_num, > + struct vhost_log *log, unsigned int *log_num) > { > int ret = fetch_descs(vq); > int i; > @@ -2311,6 +2310,8 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > *out_num = *in_num = 0; > if (unlikely(log)) > *log_num = 0; > + buf->in_len = buf->out_len = 0; > + buf->descs = 0; > > for (i = vq->first_desc; i < vq->ndescs; ++i) { > unsigned iov_count = *in_num + *out_num; > @@ -2340,6 +2341,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > /* If this is an input descriptor, > * increment that count. */ > *in_num += ret; > + buf->in_len += desc->len; > if (unlikely(log && ret)) { > log[*log_num].addr = desc->addr; > log[*log_num].len = desc->len; > @@ -2355,9 +2357,11 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > goto err; > } > *out_num += ret; > + buf->out_len += desc->len; > } > > - ret = desc->id; > + buf->id = desc->id; > + ++buf->descs; > > if (!(desc->flags & VRING_DESC_F_NEXT)) > break; > @@ -2365,7 +2369,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > > vq->first_desc = i + 1; > > - return ret; > + return 1; > > err: > for (i = vq->first_desc; i < vq->ndescs; ++i) > @@ -2375,7 +2379,15 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, > > return ret; > } > -EXPORT_SYMBOL_GPL(vhost_get_vq_desc); > +EXPORT_SYMBOL_GPL(vhost_get_avail_buf); > + > +/* Reverse the effect of vhost_get_avail_buf. Useful for error handling. */ > +void vhost_discard_avail_bufs(struct vhost_virtqueue *vq, > + struct vhost_buf *buf, unsigned count) > +{ > + vhost_discard_vq_desc(vq, count); > +} > +EXPORT_SYMBOL_GPL(vhost_discard_avail_bufs); > > static int __vhost_add_used_n(struct vhost_virtqueue *vq, > struct vring_used_elem *heads, > @@ -2459,6 +2471,26 @@ int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) > } > EXPORT_SYMBOL_GPL(vhost_add_used); > > +int vhost_put_used_buf(struct vhost_virtqueue *vq, struct vhost_buf *buf) > +{ > + return vhost_add_used(vq, buf->id, buf->in_len); > +} > +EXPORT_SYMBOL_GPL(vhost_put_used_buf); > + > +int vhost_put_used_n_bufs(struct vhost_virtqueue *vq, > + struct vhost_buf *bufs, unsigned count) > +{ > + unsigned i; > + > + for (i = 0; i < count; ++i) { > + vq->heads[i].id = cpu_to_vhost32(vq, bufs[i].id); > + vq->heads[i].len = cpu_to_vhost32(vq, bufs[i].in_len); > + } > + > + return vhost_add_used_n(vq, vq->heads, count); > +} > +EXPORT_SYMBOL_GPL(vhost_put_used_n_bufs); > + > static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq) > { > __u16 old, new; > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index a67bda9792ec..6c10e99ff334 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -67,6 +67,13 @@ struct vhost_desc { > u16 id; > }; > > +struct vhost_buf { > + u32 out_len; > + u32 in_len; > + u16 descs; > + u16 id; > +}; So it looks to me the struct vhost_buf can work for both split ring and packed ring. If this is true, we'd better make struct vhost_desc work for both. Thanks > + > /* The virtqueue structure describes a queue attached to a device. */ > struct vhost_virtqueue { > struct vhost_dev *dev; > @@ -193,7 +200,12 @@ int vhost_get_vq_desc(struct vhost_virtqueue *, > unsigned int *out_num, unsigned int *in_num, > struct vhost_log *log, unsigned int *log_num); > void vhost_discard_vq_desc(struct vhost_virtqueue *, int n); > - > +int vhost_get_avail_buf(struct vhost_virtqueue *, struct vhost_buf *buf, > + struct iovec iov[], unsigned int iov_count, > + unsigned int *out_num, unsigned int *in_num, > + struct vhost_log *log, unsigned int *log_num); > +void vhost_discard_avail_bufs(struct vhost_virtqueue *, > + struct vhost_buf *, unsigned count); > int vhost_vq_init_access(struct vhost_virtqueue *); > int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len); > int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads, > @@ -202,6 +214,9 @@ void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *, > unsigned int id, int len); > void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *, > struct vring_used_elem *heads, unsigned count); > +int vhost_put_used_buf(struct vhost_virtqueue *, struct vhost_buf *buf); > +int vhost_put_used_n_bufs(struct vhost_virtqueue *, > + struct vhost_buf *bufs, unsigned count); > void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *); > void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *); > bool vhost_vq_avail_empty(struct vhost_dev *, struct vhost_virtqueue *);