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 0B3D1C433EF for ; Mon, 4 Jul 2022 02:22:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230126AbiGDCWr (ORCPT ); Sun, 3 Jul 2022 22:22:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51944 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229502AbiGDCWq (ORCPT ); Sun, 3 Jul 2022 22:22:46 -0400 Received: from out30-54.freemail.mail.aliyun.com (out30-54.freemail.mail.aliyun.com [115.124.30.54]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C02CA64FE; Sun, 3 Jul 2022 19:22:44 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R281e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046060;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=36;SR=0;TI=SMTPD_---0VIE1rLs_1656901358; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VIE1rLs_1656901358) by smtp.aliyun-inc.com; Mon, 04 Jul 2022 10:22:39 +0800 Message-ID: <1656901259.0328152-3-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v11 22/40] virtio_ring: introduce virtqueue_resize() Date: Mon, 4 Jul 2022 10:20:59 +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: <20220629065656.54420-1-xuanzhuo@linux.alibaba.com> <20220629065656.54420-23-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 Fri, 1 Jul 2022 17:31:34 +0800, Jason Wang wrote: > > =E5=9C=A8 2022/6/29 14:56, Xuan Zhuo =E5=86=99=E9=81=93: > > Introduce virtqueue_resize() to implement the resize of vring. > > Based on these, the driver can dynamically adjust the size of the vring. > > For example: ethtool -G. > > > > virtqueue_resize() implements resize based on the vq reset function. In > > case of failure to allocate a new vring, it will give up resize and use > > the original vring. > > > > During this process, if the re-enable reset vq fails, the vq can no > > longer be used. Although the probability of this situation is not high. > > > > The parameter recycle is used to recycle the buffer that is no longer > > used. > > > > Signed-off-by: Xuan Zhuo > > --- > > drivers/virtio/virtio_ring.c | 72 ++++++++++++++++++++++++++++++++++++ > > include/linux/virtio.h | 3 ++ > > 2 files changed, 75 insertions(+) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 4860787286db..5ec43607cc15 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -2542,6 +2542,78 @@ struct virtqueue *vring_create_virtqueue( > > } > > EXPORT_SYMBOL_GPL(vring_create_virtqueue); > > > > +/** > > + * virtqueue_resize - resize the vring of vq > > + * @_vq: the struct virtqueue we're talking about. > > + * @num: new ring num > > + * @recycle: callback for recycle the useless buffer > > + * > > + * When it is really necessary to create a new vring, it will set the = current vq > > + * into the reset state. Then call the passed callback to recycle the = buffer > > + * that is no longer used. Only after the new vring is successfully cr= eated, the > > + * old vring will be released. > > + * > > + * Caller must ensure we don't call this with other virtqueue operatio= ns > > + * at the same time (except where noted). > > + * > > + * Returns zero or a negative error. > > + * 0: success. > > + * -ENOMEM: Failed to allocate a new ring, fall back to the original r= ing size. > > + * vq can still work normally > > + * -EBUSY: Failed to sync with device, vq may not work properly > > + * -ENOENT: Transport or device not supported > > + * -E2BIG/-EINVAL: num error > > + * -EPERM: Operation not permitted > > + * > > + */ > > +int virtqueue_resize(struct virtqueue *_vq, u32 num, > > + void (*recycle)(struct virtqueue *vq, void *buf)) > > +{ > > + struct vring_virtqueue *vq =3D to_vvq(_vq); > > + struct virtio_device *vdev =3D vq->vq.vdev; > > + bool packed; > > + void *buf; > > + int err; > > + > > + if (!vq->we_own_ring) > > + return -EPERM; > > + > > + if (num > vq->vq.num_max) > > + return -E2BIG; > > + > > + if (!num) > > + return -EINVAL; > > + > > + packed =3D virtio_has_feature(vdev, VIRTIO_F_RING_PACKED) ? true : fa= lse; > > > vq->packed_ring? Will fix. > > > > + > > + if ((packed ? vq->packed.vring.num : vq->split.vring.num) =3D=3D num) > > + return 0; > > + > > + if (!vdev->config->reset_vq) > > + return -ENOENT; > > + > > + if (!vdev->config->enable_reset_vq) > > + return -ENOENT; > > > Not sure this is useful, e.g driver may choose to resize after a reset > of the device? There may be some misunderstandings, this is to check whether the transport= has set the callback enable_reset_vq(). Thanks. > > Thanks > > > > + > > + err =3D vdev->config->reset_vq(_vq); > > + if (err) > > + return err; > > + > > + while ((buf =3D virtqueue_detach_unused_buf(_vq)) !=3D NULL) > > + recycle(_vq, buf); > > + > > + if (packed) > > + err =3D virtqueue_resize_packed(_vq, num); > > + else > > + err =3D virtqueue_resize_split(_vq, num); > > + > > + if (vdev->config->enable_reset_vq(_vq)) > > + return -EBUSY; > > + > > + return err; > > +} > > +EXPORT_SYMBOL_GPL(virtqueue_resize); > > + > > /* Only available for split ring */ > > struct virtqueue *vring_new_virtqueue(unsigned int index, > > unsigned int num, > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > > index a82620032e43..1272566adec6 100644 > > --- a/include/linux/virtio.h > > +++ b/include/linux/virtio.h > > @@ -91,6 +91,9 @@ dma_addr_t virtqueue_get_desc_addr(struct virtqueue *= vq); > > dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq); > > dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq); > > > > +int virtqueue_resize(struct virtqueue *vq, u32 num, > > + void (*recycle)(struct virtqueue *vq, void *buf)); > > + > > /** > > * virtio_device - representation of a device using virtio > > * @index: unique position on the virtio bus >