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 E7C46C433EF for ; Fri, 22 Jul 2022 03:58:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233592AbiGVD57 (ORCPT ); Thu, 21 Jul 2022 23:57:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229692AbiGVD54 (ORCPT ); Thu, 21 Jul 2022 23:57:56 -0400 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 136CD6C105; Thu, 21 Jul 2022 20:57:52 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=36;SR=0;TI=SMTPD_---0VK3SFm4_1658462266; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VK3SFm4_1658462266) by smtp.aliyun-inc.com; Fri, 22 Jul 2022 11:57:47 +0800 Message-ID: <1658461678.632858-2-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v12 08/40] virtio_ring: split: extract the logic of alloc queue Date: Fri, 22 Jul 2022 11:47:58 +0800 From: Xuan Zhuo To: Jason Wang Cc: Richard Weinberger , Anton Ivanov , Johannes Berg , "Michael S. Tsirkin" , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Hans de Goede , Mark Gross , Vadim Pasternak , Bjorn Andersson , Mathieu Poirier , Cornelia Huck , Halil Pasic , Eric Farman , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Vincent Whitchurch , linux-um@lists.infradead.org, netdev@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, bpf@vger.kernel.org, kangjie.xu@linux.alibaba.com, virtualization@lists.linux-foundation.org References: <20220720030436.79520-1-xuanzhuo@linux.alibaba.com> <20220720030436.79520-9-xuanzhuo@linux.alibaba.com> <0b3c985d-d479-a554-4fe2-bfe94fc74070@redhat.com> In-Reply-To: <0b3c985d-d479-a554-4fe2-bfe94fc74070@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org On Thu, 21 Jul 2022 17:13:49 +0800, Jason Wang wrote: > > =E5=9C=A8 2022/7/20 11:04, Xuan Zhuo =E5=86=99=E9=81=93: > > Separate the logic of split to create vring queue. > > > > This feature is required for subsequent virtuqueue reset vring. > > > > Signed-off-by: Xuan Zhuo > > --- > > drivers/virtio/virtio_ring.c | 68 ++++++++++++++++++++++-------------- > > 1 file changed, 42 insertions(+), 26 deletions(-) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index c94c5461e702..c7971438bb2c 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -950,28 +950,19 @@ static void vring_free_split(struct vring_virtque= ue_split *vring_split, > > kfree(vring_split->desc_extra); > > } > > > > -static struct virtqueue *vring_create_virtqueue_split( > > - unsigned int index, > > - unsigned int num, > > - unsigned int vring_align, > > - struct virtio_device *vdev, > > - bool weak_barriers, > > - bool may_reduce_num, > > - bool context, > > - bool (*notify)(struct virtqueue *), > > - void (*callback)(struct virtqueue *), > > - const char *name) > > +static int vring_alloc_queue_split(struct vring_virtqueue_split *vring= _split, > > + struct virtio_device *vdev, > > + u32 num, > > + unsigned int vring_align, > > + bool may_reduce_num) > > { > > - struct virtqueue *vq; > > void *queue =3D NULL; > > dma_addr_t dma_addr; > > - size_t queue_size_in_bytes; > > - struct vring vring; > > > > /* We assume num is a power of 2. */ > > if (num & (num - 1)) { > > dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num); > > - return NULL; > > + return -EINVAL; > > } > > > > /* TODO: allocate each queue chunk individually */ > > @@ -982,11 +973,11 @@ static struct virtqueue *vring_create_virtqueue_s= plit( > > if (queue) > > break; > > if (!may_reduce_num) > > - return NULL; > > + return -ENOMEM; > > } > > > > if (!num) > > - return NULL; > > + return -ENOMEM; > > > > if (!queue) { > > /* Try to get a single page. You are my only hope! */ > > @@ -994,21 +985,46 @@ static struct virtqueue *vring_create_virtqueue_s= plit( > > &dma_addr, GFP_KERNEL|__GFP_ZERO); > > } > > if (!queue) > > - return NULL; > > + return -ENOMEM; > > + > > + vring_init(&vring_split->vring, num, queue, vring_align); > > > > - queue_size_in_bytes =3D vring_size(num, vring_align); > > - vring_init(&vring, num, queue, vring_align); > > + vring_split->queue_dma_addr =3D dma_addr; > > + vring_split->queue_size_in_bytes =3D vring_size(num, vring_align); > > + > > + return 0; > > +} > > + > > +static struct virtqueue *vring_create_virtqueue_split( > > + unsigned int index, > > + unsigned int num, > > + unsigned int vring_align, > > + struct virtio_device *vdev, > > + bool weak_barriers, > > + bool may_reduce_num, > > + bool context, > > + bool (*notify)(struct virtqueue *), > > + void (*callback)(struct virtqueue *), > > + const char *name) > > +{ > > + struct vring_virtqueue_split vring_split =3D {}; > > + struct virtqueue *vq; > > + int err; > > + > > + err =3D vring_alloc_queue_split(&vring_split, vdev, num, vring_align, > > + may_reduce_num); > > + if (err) > > + return NULL; > > > > - vq =3D __vring_new_virtqueue(index, vring, vdev, weak_barriers, conte= xt, > > - notify, callback, name); > > + vq =3D __vring_new_virtqueue(index, vring_split.vring, vdev, weak_bar= riers, > > + context, notify, callback, name); > > if (!vq) { > > - vring_free_queue(vdev, queue_size_in_bytes, queue, > > - dma_addr); > > + vring_free_split(&vring_split, vdev); > > return NULL; > > } > > > > - to_vvq(vq)->split.queue_dma_addr =3D dma_addr; > > - to_vvq(vq)->split.queue_size_in_bytes =3D queue_size_in_bytes; > > + to_vvq(vq)->split.queue_dma_addr =3D vring_split.queue_dma_addr; > > + to_vvq(vq)->split.queue_size_in_bytes =3D vring_split.queue_size_in_b= ytes; > > > This still seems a little bit redundant since the current logic is a > little bit complicated since the vq->split is not initialized in a > single place. > > I wonder if it's better to: > > vring_alloc_queue_split() > vring_alloc_desc_extra() (reorder to make patch 9 come first) > > then we can simply assign vring_split to vq->split in > __vring_new_virtqueue() since it has: > > =C2=A0=C2=A0=C2=A0 vq->split.queue_dma_addr =3D 0; > =C2=A0=C2=A0 =C2=A0vq->split.queue_size_in_bytes =3D 0; > > =C2=A0=C2=A0=C2=A0 vq->split.vring =3D vring; > =C2=A0=C2=A0=C2=A0 vq->split.avail_flags_shadow =3D 0; > =C2=A0=C2=A0=C2=A0 vq->split.avail_idx_shadow =3D 0; > > This seems to simplify the logic and task of e.g > virtqueue_vring_attach_split() to a simple: > > vq->split=3D vring_split; This does look simpler. The reason for not doing this is that the argument accepted by __vring_new_virtqueue() is "struct vring", and __vring_new_virtqueue() is an export symbol. I took a look, and the only external direct call to __vring_new_virtqueue is here. tools/virtio/virtio_test.c static void vq_reset(struct vq_info *info, int num, struct virtio_device *= vdev) { if (info->vq) vring_del_virtqueue(info->vq); memset(info->ring, 0, vring_size(num, 4096)); vring_init(&info->vring, num, info->ring, 4096); info->vq =3D __vring_new_virtqueue(info->idx, info->vring, vdev, true, false, vq_notify, vq_callback, "test"); assert(info->vq); info->vq->priv =3D info; } I think this could be replaced with vring_new_virtqueue() so that we don't = need to make __vring_new_virtqueue as an export function so we can make some modifications to it. nit: vring_alloc_desc_extra() should not have to be extract from __vring_new_virtqueue() . Thanks. > > And if this makes sense, we can do something similar to packed ring. > > Thanks > > > > to_vvq(vq)->we_own_ring =3D true; > > > > return vq; >