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 F3CB4C433FE for ; Wed, 13 Apr 2022 06:41:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233060AbiDMGnV (ORCPT ); Wed, 13 Apr 2022 02:43:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233041AbiDMGnU (ORCPT ); Wed, 13 Apr 2022 02:43:20 -0400 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F5ED286C0; Tue, 12 Apr 2022 23:40:58 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R381e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=33;SR=0;TI=SMTPD_---0V9yQeE6_1649832051; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0V9yQeE6_1649832051) by smtp.aliyun-inc.com(127.0.0.1); Wed, 13 Apr 2022 14:40:53 +0800 Message-ID: <1649831529.7724812-5-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v9 11/32] virtio_ring: split: introduce virtqueue_resize_split() Date: Wed, 13 Apr 2022 14:32:09 +0800 From: Xuan Zhuo To: Jason Wang Cc: Jeff Dike , Richard Weinberger , Anton Ivanov , "Michael S. Tsirkin" , "David S. Miller" , Jakub Kicinski , Hans de Goede , Mark Gross , Vadim Pasternak , Bjorn Andersson , Mathieu Poirier , Cornelia Huck , Halil Pasic , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Alexander Gordeev , Sven Schnelle , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Johannes Berg , 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, virtualization@lists.linux-foundation.org References: <20220406034346.74409-1-xuanzhuo@linux.alibaba.com> <20220406034346.74409-12-xuanzhuo@linux.alibaba.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Tue, 12 Apr 2022 13:53:44 +0800, Jason Wang wrote: > > =E5=9C=A8 2022/4/6 =E4=B8=8A=E5=8D=8811:43, Xuan Zhuo =E5=86=99=E9=81=93: > > virtio ring split supports resize. > > > > Only after the new vring is successfully allocated based on the new num, > > we will release the old vring. In any case, an error is returned, > > indicating that the vring still points to the old vring. > > > > In the case of an error, the caller must > > re-initialize(virtqueue_reinit_split()) the virtqueue to ensure that the > > vring can be used. > > > > In addition, vring_align, may_reduce_num are necessary for reallocating > > vring, so they are retained for creating vq. > > > > Signed-off-by: Xuan Zhuo > > --- > > drivers/virtio/virtio_ring.c | 47 ++++++++++++++++++++++++++++++++++++ > > 1 file changed, 47 insertions(+) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 3dc6ace2ba7a..33864134a744 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -139,6 +139,12 @@ struct vring_virtqueue { > > /* DMA address and size information */ > > dma_addr_t queue_dma_addr; > > size_t queue_size_in_bytes; > > + > > + /* The parameters for creating vrings are reserved for > > + * creating new vring. > > + */ > > + u32 vring_align; > > + bool may_reduce_num; > > } split; > > > > /* Available for packed ring */ > > @@ -199,6 +205,7 @@ struct vring_virtqueue { > > }; > > > > static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int n= um); > > +static void vring_free(struct virtqueue *_vq); > > > > /* > > * Helpers. > > @@ -1088,6 +1095,8 @@ static struct virtqueue *vring_create_virtqueue_s= plit( > > return NULL; > > } > > > > + to_vvq(vq)->split.vring_align =3D vring_align; > > + to_vvq(vq)->split.may_reduce_num =3D may_reduce_num; > > > It looks to me the above should belong to patch 6. patch 6 just extracts a function, no logical modification. to_vvq(vq)->split.may_reduce_num is newly added, so I don't think it should= be merged into patch 6. > > > > 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)->we_own_ring =3D true; > > @@ -1095,6 +1104,44 @@ static struct virtqueue *vring_create_virtqueue_= split( > > return vq; > > } > > > > +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num) > > +{ > > + struct vring_virtqueue *vq =3D to_vvq(_vq); > > + struct virtio_device *vdev =3D _vq->vdev; > > + struct vring_desc_state_split *state; > > + struct vring_desc_extra *extra; > > + size_t queue_size_in_bytes; > > + dma_addr_t dma_addr; > > + struct vring vring; > > + int err =3D -ENOMEM; > > + void *queue; > > + > > + queue =3D vring_alloc_queue_split(vdev, &dma_addr, &num, > > + vq->split.vring_align, > > + vq->weak_barriers, > > + vq->split.may_reduce_num); > > + if (!queue) > > + return -ENOMEM; > > + > > + queue_size_in_bytes =3D vring_size(num, vq->split.vring_align); > > + > > + err =3D vring_alloc_state_extra_split(num, &state, &extra); > > + if (err) { > > + vring_free_queue(vdev, queue_size_in_bytes, queue, dma_addr); > > + return -ENOMEM; > > + } > > + > > + vring_free(&vq->vq); > > + > > + vring_init(&vring, num, queue, vq->split.vring_align); > > + vring_virtqueue_attach_split(vq, vring, state, extra); > > + vq->split.queue_dma_addr =3D dma_addr; > > + vq->split.queue_size_in_bytes =3D queue_size_in_bytes; > > > I wonder if it's better to move the above assignments to > vring_virtqueue_attach_split(). I also think so, the reason for not doing this is that there is no dma_addr= and queue_size_in_bytes when vring_virtqueue_attach_split is called in __vring_new_virtqueue. As discussed in patch 12, we can pass the struct struct vring_virtqueue_spl= it to vring_virtqueue_attach_split(). This is much more convenient. Thanks. > > Other looks good. > > Thanks > > > > + > > + vring_virtqueue_init_split(vq, vdev, true); > > + return 0; > > +} > > + > > > > /* > > * Packed ring specific functions - *_packed(). >