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=-6.9 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 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 2CE68C433E0 for ; Thu, 4 Jun 2020 09:03:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA697206C3 for ; Thu, 4 Jun 2020 09:03:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fPcz5jBQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728447AbgFDJDc (ORCPT ); Thu, 4 Jun 2020 05:03:32 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:38322 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728259AbgFDJDb (ORCPT ); Thu, 4 Jun 2020 05:03:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591261409; 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=kIAb7NyvRkDdFjS5z3YNHayJvBeusj5SE6fr0SttD8A=; b=fPcz5jBQ+JKfNWFuAWktKK19jLgDtZpkts0Qtc0pLpVjxVZGpuFPxHIAEfRQ05HIApTObE FtOtq1fuR7+J2d3gFOnn19qU5ZR+7IER5GSul90U2c9el25EFeF+Ss51qviKyBkOX98zZj Cc9r9qlcX2dHiCEErv/20gzs+t58GQE= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-308-fzfd5c4QNNuFahRLCM1DAw-1; Thu, 04 Jun 2020 05:03:27 -0400 X-MC-Unique: fzfd5c4QNNuFahRLCM1DAw-1 Received: by mail-wr1-f71.google.com with SMTP id o1so2132648wrm.17 for ; Thu, 04 Jun 2020 02:03:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=kIAb7NyvRkDdFjS5z3YNHayJvBeusj5SE6fr0SttD8A=; b=bSx9FfVB7DAFg7LbkhUKf+14Zs0PkzrikI5U+7G/bJxgzFnUn/UGqJAQ/tbWBmiVh/ 7+N/VYp7AEw0xFwkBZfuAKkAE6KNQVjZl2Uu9lYAEUeJkFBGou89/8g5tTYBuEzulGN7 kgZcVCziw7JcT5bXWsJ0blxhwcNrqFDU/5svRl4+FxYo2CvV9puRdrNSVvk7i49c0Jg8 cN0x3qEp1vaVat/i65R8Ea52JsxOUUrKqTjFXqZBQbulRNzgno2OAK7yE8jyjVwCVr7+ 0o61f1LB0VETAppba3W3usVvpLiHinDi2nxb5yIxSlOcjMYdFYXW/GoKjgXYKbtERC6n UIwg== X-Gm-Message-State: AOAM531GHjiXSgoewnFbQfI0BLJHGey390ivYx9CMI5/A/Hk4a52u6b9 9yIIYnIsGfUptHnUcu3n4agOS3cALyaIayKnlq5f2j8hdv8bLQA1Ec0Hs615G4AQBhSVpHIL/q/ gd6uuYrBSO7Z7uw2Rt5thEYx1 X-Received: by 2002:a7b:c84b:: with SMTP id c11mr2984630wml.78.1591261406175; Thu, 04 Jun 2020 02:03:26 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzK8wfsCxu3E9p7ycUHfNx0D5YgutQJ5LV0RZsf7ra/tC4JM/gzDFfv1l4UJCevPLTlT9guOg== X-Received: by 2002:a7b:c84b:: with SMTP id c11mr2984604wml.78.1591261405902; Thu, 04 Jun 2020 02:03:25 -0700 (PDT) Received: from redhat.com ([2a00:a040:185:f65:9a3b:8fff:fed3:ad8d]) by smtp.gmail.com with ESMTPSA id u12sm7129873wrq.90.2020.06.04.02.03.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Jun 2020 02:03:25 -0700 (PDT) Date: Thu, 4 Jun 2020 05:03:20 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: linux-kernel@vger.kernel.org, Eugenio =?iso-8859-1?Q?P=E9rez?= , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: Re: [PATCH RFC 07/13] vhost: format-independent API for used buffers Message-ID: <20200604050135-mutt-send-email-mst@kernel.org> References: <20200602130543.578420-1-mst@redhat.com> <20200602130543.578420-8-mst@redhat.com> <6d98f2cc-2084-cde0-c938-4ca01692adf9@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6d98f2cc-2084-cde0-c938-4ca01692adf9@redhat.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 03, 2020 at 03:58:26PM +0800, Jason Wang wrote: > > 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 Both vhost_desc and vhost_buf can work for split and packed. Do you mean we should add packed ring support based on this? For sure, this is one of the motivators for the patchset. > > > + > > /* 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 *);