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From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Mark Gross <markgross@kernel.org>,
	Vadim Pasternak <vadimp@nvidia.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Cornelia Huck <cohuck@redhat.com>,
	Halil Pasic <pasic@linux.ibm.com>,
	Eric Farman <farman@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	Vincent Whitchurch <vincent.whitchurch@axis.com>,
	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
Subject: Re: [PATCH v12 08/40] virtio_ring: split: extract the logic of alloc queue
Date: Fri, 22 Jul 2022 11:47:58 +0800	[thread overview]
Message-ID: <1658461678.632858-2-xuanzhuo@linux.alibaba.com> (raw)
In-Reply-To: <0b3c985d-d479-a554-4fe2-bfe94fc74070@redhat.com>

On Thu, 21 Jul 2022 17:13:49 +0800, Jason Wang <jasowang@redhat.com> wrote:
>
> 在 2022/7/20 11:04, Xuan Zhuo 写道:
> > Separate the logic of split to create vring queue.
> >
> > This feature is required for subsequent virtuqueue reset vring.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >   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_virtqueue_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 = 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_split(
> >   		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_split(
> >   					  &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 = vring_size(num, vring_align);
> > -	vring_init(&vring, num, queue, vring_align);
> > +	vring_split->queue_dma_addr = dma_addr;
> > +	vring_split->queue_size_in_bytes = 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 = {};
> > +	struct virtqueue *vq;
> > +	int err;
> > +
> > +	err = vring_alloc_queue_split(&vring_split, vdev, num, vring_align,
> > +				      may_reduce_num);
> > +	if (err)
> > +		return NULL;
> >
> > -	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
> > -				   notify, callback, name);
> > +	vq = __vring_new_virtqueue(index, vring_split.vring, vdev, weak_barriers,
> > +				   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 = dma_addr;
> > -	to_vvq(vq)->split.queue_size_in_bytes = queue_size_in_bytes;
> > +	to_vvq(vq)->split.queue_dma_addr = vring_split.queue_dma_addr;
> > +	to_vvq(vq)->split.queue_size_in_bytes = vring_split.queue_size_in_bytes;
>
>
> 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:
>
>      vq->split.queue_dma_addr = 0;
>      vq->split.queue_size_in_bytes = 0;
>
>      vq->split.vring = vring;
>      vq->split.avail_flags_shadow = 0;
>      vq->split.avail_idx_shadow = 0;
>
> This seems to simplify the logic and task of e.g
> virtqueue_vring_attach_split() to a simple:
>
> vq->split= 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 = __vring_new_virtqueue(info->idx, info->vring, vdev, true,
						 false, vq_notify, vq_callback, "test");
		assert(info->vq);
		info->vq->priv = 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 = true;
> >
> >   	return vq;
>

  reply	other threads:[~2022-07-22  3:58 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-20  3:03 [PATCH v12 00/40] virtio pci support VIRTIO_F_RING_RESET Xuan Zhuo
2022-07-20  3:03 ` [PATCH v12 01/40] virtio: record the maximum queue num supported by the device Xuan Zhuo
2022-07-21  3:36   ` Jason Wang
2022-07-20  3:03 ` [PATCH v12 02/40] virtio: struct virtio_config_ops add callbacks for queue_reset Xuan Zhuo
2022-07-21  3:39   ` Jason Wang
2022-07-20  3:03 ` [PATCH v12 03/40] virtio_ring: update the document of the virtqueue_detach_unused_buf for queue reset Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 04/40] virtio_ring: extract the logic of freeing vring Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 05/40] virtio_ring: split vring_virtqueue Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 06/40] virtio_ring: introduce virtqueue_init() Xuan Zhuo
2022-07-21  7:07   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 07/40] virtio_ring: split: introduce vring_free_split() Xuan Zhuo
2022-07-21  7:08   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 08/40] virtio_ring: split: extract the logic of alloc queue Xuan Zhuo
2022-07-21  9:13   ` Jason Wang
2022-07-22  3:47     ` Xuan Zhuo [this message]
2022-07-20  3:04 ` [PATCH v12 09/40] virtio_ring: split: extract the logic of alloc state and extra Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 10/40] virtio_ring: split: extract the logic of attach vring Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 11/40] virtio_ring: split: extract the logic of vring init Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 12/40] virtio_ring: split: introduce virtqueue_reinit_split() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 13/40] virtio_ring: split: reserve vring_align, may_reduce_num Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 14/40] virtio_ring: split: introduce virtqueue_resize_split() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 15/40] virtio_ring: packed: introduce vring_free_packed Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 16/40] virtio_ring: packed: extract the logic of alloc queue Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 17/40] virtio_ring: packed: extract the logic of alloc state and extra Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 18/40] virtio_ring: packed: extract the logic of attach vring Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 19/40] virtio_ring: packed: extract the logic of vring init Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 20/40] virtio_ring: packed: introduce virtqueue_reinit_packed() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 21/40] virtio_ring: packed: introduce virtqueue_resize_packed() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 22/40] virtio_ring: introduce virtqueue_resize() Xuan Zhuo
2022-07-21  9:15   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 23/40] virtio_pci: struct virtio_pci_common_cfg add queue_notify_data Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 24/40] virtio: allow to unbreak/break virtqueue individually Xuan Zhuo
2022-07-21  9:14   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 25/40] virtio: queue_reset: add VIRTIO_F_RING_RESET Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 26/40] virtio_ring: struct virtqueue introduce reset Xuan Zhuo
2022-07-21  9:14   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 27/40] virtio_pci: struct virtio_pci_common_cfg add queue_reset Xuan Zhuo
2022-07-21  9:14   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 28/40] virtio_pci: introduce helper to get/set queue reset Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 29/40] virtio_pci: extract the logic of active vq for modern pci Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 30/40] virtio_pci: support VIRTIO_F_RING_RESET Xuan Zhuo
2022-07-21  9:15   ` Jason Wang
2022-07-22  3:05     ` Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 31/40] virtio: find_vqs() add arg sizes Xuan Zhuo
2022-07-21  9:17   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 32/40] virtio_pci: support the arg sizes of find_vqs() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 33/40] virtio_mmio: " Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 34/40] virtio: add helper virtio_find_vqs_ctx_size() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 35/40] virtio_net: set the default max ring size by find_vqs() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 36/40] virtio_net: get ringparam by virtqueue_get_vring_max_size() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 37/40] virtio_net: split free_unused_bufs() Xuan Zhuo
2022-07-20  3:04 ` [PATCH v12 38/40] virtio_net: support rx queue resize Xuan Zhuo
2022-07-21  9:25   ` Jason Wang
2022-07-25  6:38     ` Xuan Zhuo
2022-07-25  6:57       ` Jason Wang
2022-07-25  7:21         ` Xuan Zhuo
2022-07-25  7:28           ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 39/40] virtio_net: support tx " Xuan Zhuo
2022-07-21  9:30   ` Jason Wang
2022-07-20  3:04 ` [PATCH v12 40/40] virtio_net: support set_ringparam Xuan Zhuo

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