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 9796DC433F5 for ; Wed, 16 Feb 2022 07:55:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231202AbiBPHzL (ORCPT ); Wed, 16 Feb 2022 02:55:11 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:47916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229528AbiBPHzL (ORCPT ); Wed, 16 Feb 2022 02:55:11 -0500 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 CEE0F1FFF7D; Tue, 15 Feb 2022 23:54:54 -0800 (PST) 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=e01e01424;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0V4c7G.H_1644998091; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0V4c7G.H_1644998091) by smtp.aliyun-inc.com(127.0.0.1); Wed, 16 Feb 2022 15:54:52 +0800 Message-ID: <1644998063.772229-2-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v5 19/22] virtio: add helper virtio_set_max_ring_num() Date: Wed, 16 Feb 2022 15:54:23 +0800 From: Xuan Zhuo To: Jason Wang Cc: virtualization , netdev , "Michael S. Tsirkin" , "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , bpf@vger.kernel.org References: <20220214081416.117695-1-xuanzhuo@linux.alibaba.com> <20220214081416.117695-20-xuanzhuo@linux.alibaba.com> In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, 16 Feb 2022 12:14:04 +0800, Jason Wang wrote: > On Mon, Feb 14, 2022 at 4:15 PM Xuan Zhuo wrote: > > > > Added helper virtio_set_max_ring_num() to set the upper limit of ring > > num when creating a virtqueue. > > > > Can be used to limit ring num before find_vqs() call. Or change ring num > > when re-enable reset queue. > > Do we have a chance that RX and TX may want different ring size? If > yes, it might be even better to have per vq limit via find_vqs()? > > > > > Signed-off-by: Xuan Zhuo > > --- > > drivers/virtio/virtio_ring.c | 6 ++++++ > > include/linux/virtio.h | 1 + > > include/linux/virtio_config.h | 30 ++++++++++++++++++++++++++++++ > > 3 files changed, 37 insertions(+) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 1a123b5e5371..a77a82883e44 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -943,6 +943,9 @@ static struct virtqueue *vring_create_virtqueue_split( > > size_t queue_size_in_bytes; > > struct vring vring; > > > > + if (vdev->max_ring_num && num > vdev->max_ring_num) > > + num = vdev->max_ring_num; > > + > > /* We assume num is a power of 2. */ > > if (num & (num - 1)) { > > dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num); > > @@ -1692,6 +1695,9 @@ static struct virtqueue *vring_create_virtqueue_packed( > > dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr; > > size_t ring_size_in_bytes, event_size_in_bytes; > > > > + if (vdev->max_ring_num && num > vdev->max_ring_num) > > + num = vdev->max_ring_num; > > + > > ring_size_in_bytes = num * sizeof(struct vring_packed_desc); > > > > ring = vring_alloc_queue(vdev, ring_size_in_bytes, > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > > index 1153b093c53d..45525beb2ec4 100644 > > --- a/include/linux/virtio.h > > +++ b/include/linux/virtio.h > > @@ -127,6 +127,7 @@ struct virtio_device { > > struct list_head vqs; > > u64 features; > > void *priv; > > + u16 max_ring_num; > > }; > > > > static inline struct virtio_device *dev_to_virtio(struct device *_dev) > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > > index cd7f7f44ce38..d7cb2d0341ee 100644 > > --- a/include/linux/virtio_config.h > > +++ b/include/linux/virtio_config.h > > @@ -200,6 +200,36 @@ static inline bool virtio_has_dma_quirk(const struct virtio_device *vdev) > > return !virtio_has_feature(vdev, VIRTIO_F_ACCESS_PLATFORM); > > } > > > > +/** > > + * virtio_set_max_ring_num - set max ring num > > + * @vdev: the device > > + * @num: max ring num. Zero clear the limit. > > + * > > + * When creating a virtqueue, use this value as the upper limit of ring num. > > + * > > + * Returns 0 on success or error status > > + */ > > +static inline > > +int virtio_set_max_ring_num(struct virtio_device *vdev, u16 num) > > +{ > > Having a dedicated helper for a per device parameter usually means the > use cases are greatly limited. For example, this seems can only be > used when DRIVER_OK is not set? > > And in patch 17 this function is called even if we only modify the RX > size, this is probably another call for a more flexible API as I > suggest like exporting vring allocation/deallocation helper and extend > find_vqs()? > I understand. Thanks. > Thanks > > > > + if (!num) { > > + vdev->max_ring_num = num; > > + return 0; > > + } > > + > > + if (!virtio_has_feature(vdev, VIRTIO_F_RING_PACKED)) { > > + if (!is_power_of_2(num)) { > > + num = __rounddown_pow_of_two(num); > > + > > + if (!num) > > + return -EINVAL; > > + } > > + } > > + > > + vdev->max_ring_num = num; > > + return 0; > > +} > > + > > static inline > > struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev, > > vq_callback_t *c, const char *n) > > -- > > 2.31.0 > > >