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From: Jason Gunthorpe <jgg@mellanox.com>
To: Jason Wang <jasowang@redhat.com>
Cc: "mst@redhat.com" <mst@redhat.com>,
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Subject: Re: [PATCH 5/5] vdpasim: vDPA device simulator
Date: Thu, 16 Jan 2020 15:47:01 +0000
Message-ID: <20200116154658.GJ20978@mellanox.com> (raw)
In-Reply-To: <20200116124231.20253-6-jasowang@redhat.com>

On Thu, Jan 16, 2020 at 08:42:31PM +0800, Jason Wang wrote:
> This patch implements a software vDPA networking device. The datapath
> is implemented through vringh and workqueue. The device has an on-chip
> IOMMU which translates IOVA to PA. For kernel virtio drivers, vDPA
> simulator driver provides dma_ops. For vhost driers, set_map() methods
> of vdpa_config_ops is implemented to accept mappings from vhost.
> 
> A sysfs based management interface is implemented, devices are
> created and removed through:
> 
> /sys/devices/virtual/vdpa_simulator/netdev/{create|remove}

This is very gross, creating a class just to get a create/remove and
then not using the class for anything else? Yuk.

> Netlink based lifecycle management could be implemented for vDPA
> simulator as well.

This is just begging for a netlink based approach.

Certainly netlink driven removal should be an agreeable standard for
all devices, I think.

> +struct vdpasim_virtqueue {
> +	struct vringh vring;
> +	struct vringh_kiov iov;
> +	unsigned short head;
> +	bool ready;
> +	u64 desc_addr;
> +	u64 device_addr;
> +	u64 driver_addr;
> +	u32 num;
> +	void *private;
> +	irqreturn_t (*cb)(void *data);
> +};
> +
> +#define VDPASIM_QUEUE_ALIGN PAGE_SIZE
> +#define VDPASIM_QUEUE_MAX 256
> +#define VDPASIM_DEVICE_ID 0x1
> +#define VDPASIM_VENDOR_ID 0
> +#define VDPASIM_VQ_NUM 0x2
> +#define VDPASIM_CLASS_NAME "vdpa_simulator"
> +#define VDPASIM_NAME "netdev"
> +
> +u64 vdpasim_features = (1ULL << VIRTIO_F_ANY_LAYOUT) |
> +		       (1ULL << VIRTIO_F_VERSION_1)  |
> +		       (1ULL << VIRTIO_F_IOMMU_PLATFORM);

Is not using static here intentional?

> +static void vdpasim_release_dev(struct device *_d)
> +{
> +	struct vdpa_device *vdpa = dev_to_vdpa(_d);
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +
> +	sysfs_remove_link(vdpasim_dev->devices_kobj, vdpasim->name);
> +
> +	mutex_lock(&vsim_list_lock);
> +	list_del(&vdpasim->next);
> +	mutex_unlock(&vsim_list_lock);
> +
> +	kfree(vdpasim->buffer);
> +	kfree(vdpasim);
> +}

It is again a bit weird to see a realease function in a driver. This
stuff is usually in the remove remove function.

> +static int vdpasim_create(const guid_t *uuid)
> +{
> +	struct vdpasim *vdpasim, *tmp;
> +	struct virtio_net_config *config;
> +	struct vdpa_device *vdpa;
> +	struct device *dev;
> +	int ret = -ENOMEM;
> +
> +	mutex_lock(&vsim_list_lock);
> +	list_for_each_entry(tmp, &vsim_devices_list, next) {
> +		if (guid_equal(&tmp->uuid, uuid)) {
> +			mutex_unlock(&vsim_list_lock);
> +			return -EEXIST;
> +		}
> +	}
> +
> +	vdpasim = kzalloc(sizeof(*vdpasim), GFP_KERNEL);
> +	if (!vdpasim)
> +		goto err_vdpa_alloc;
> +
> +	vdpasim->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
> +	if (!vdpasim->buffer)
> +		goto err_buffer_alloc;
> +
> +	vdpasim->iommu = vhost_iotlb_alloc(2048, 0);
> +	if (!vdpasim->iommu)
> +		goto err_iotlb;
> +
> +	config = &vdpasim->config;
> +	config->mtu = 1500;
> +	config->status = VIRTIO_NET_S_LINK_UP;
> +	eth_random_addr(config->mac);
> +
> +	INIT_WORK(&vdpasim->work, vdpasim_work);
> +	spin_lock_init(&vdpasim->lock);
> +
> +	guid_copy(&vdpasim->uuid, uuid);
> +
> +	list_add(&vdpasim->next, &vsim_devices_list);
> +	vdpa = &vdpasim->vdpa;
> +
> +	mutex_unlock(&vsim_list_lock);
> +
> +	vdpa = &vdpasim->vdpa;
> +	vdpa->config = &vdpasim_net_config_ops;
> +	vdpa_set_parent(vdpa, &vdpasim_dev->dev);
> +	vdpa->dev.release = vdpasim_release_dev;
> +
> +	vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim->iommu);
> +	vringh_set_iotlb(&vdpasim->vqs[1].vring, vdpasim->iommu);
> +
> +	dev = &vdpa->dev;
> +	dev->coherent_dma_mask = DMA_BIT_MASK(64);
> +	set_dma_ops(dev, &vdpasim_dma_ops);
> +
> +	ret = register_vdpa_device(vdpa);
> +	if (ret)
> +		goto err_register;
> +
> +	sprintf(vdpasim->name, "%pU", uuid);
>+
> +	ret = sysfs_create_link(vdpasim_dev->devices_kobj, &vdpa->dev.kobj,
> +				vdpasim->name);
> +	if (ret)
> +		goto err_link;

The goto err_link does the wrong unwind, once register is completed
the error unwind is unregister & put_device, not kfree. This is why I
recommend to always initalize the device early, and always using
put_device during error unwinds.

This whole guid thing seems unncessary when the device is immediately
assigned a vdpa index from the ida. If you were not using syfs you'd
just return that index from the creation netlink.

Jason

  reply index

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 12:42 [PATCH 0/5] vDPA support Jason Wang
2020-01-16 12:42 ` [PATCH 1/5] vhost: factor out IOTLB Jason Wang
2020-01-17  4:14   ` Randy Dunlap
2020-01-17  9:34     ` Jason Wang
2020-01-18  0:01   ` kbuild test robot
2020-01-18  0:40   ` kbuild test robot
2020-01-16 12:42 ` [PATCH 2/5] vringh: IOTLB support Jason Wang
2020-01-17 21:54   ` kbuild test robot
2020-01-17 22:33   ` kbuild test robot
2020-01-16 12:42 ` [PATCH 3/5] vDPA: introduce vDPA bus Jason Wang
2020-01-16 15:22   ` Jason Gunthorpe
2020-01-17  3:03     ` Jason Wang
2020-01-17 13:54       ` Jason Gunthorpe
2020-01-20  7:50         ` Jason Wang
2020-01-20 12:17         ` Michael S. Tsirkin
2020-01-20 17:50           ` Jason Gunthorpe
2020-01-20 21:56             ` Michael S. Tsirkin
2020-01-21 14:12               ` Jason Gunthorpe
2020-01-21 14:15                 ` Michael S. Tsirkin
2020-01-21 14:16                   ` Jason Gunthorpe
2020-01-21  8:40       ` Tian, Kevin
2020-01-21  9:41         ` Jason Wang
2020-01-17  4:16   ` Randy Dunlap
2020-01-17  9:34     ` Jason Wang
2020-01-17 12:13   ` Michael S. Tsirkin
2020-01-17 13:52     ` Jason Wang
     [not found]       ` <CAJPjb1+fG9L3=iKbV4Vn13VwaeDZZdcfBPvarogF_Nzhk+FnKg@mail.gmail.com>
2020-01-19  9:07         ` Shahaf Shuler
2020-01-19  9:59           ` Michael S. Tsirkin
2020-01-20  8:44             ` Jason Wang
2020-01-20 12:09               ` Michael S. Tsirkin
2020-01-21  3:32                 ` Jason Wang
2020-01-20  8:43           ` Jason Wang
2020-01-20 17:49             ` Jason Gunthorpe
2020-01-20 20:51               ` Shahaf Shuler
2020-01-20 21:25                 ` Michael S. Tsirkin
2020-01-20 21:47                   ` Shahaf Shuler
2020-01-20 21:59                     ` Michael S. Tsirkin
2020-01-21  6:01                       ` Shahaf Shuler
2020-01-21  7:57                         ` Jason Wang
2020-01-21 14:07                   ` Jason Gunthorpe
2020-01-21 14:16                     ` Michael S. Tsirkin
2020-01-20 21:48               ` Michael S. Tsirkin
2020-01-21  4:00               ` Jason Wang
2020-01-21  5:47                 ` Michael S. Tsirkin
2020-01-21  8:00                   ` Jason Wang
2020-01-21  8:15                     ` Michael S. Tsirkin
2020-01-21  8:35                       ` Jason Wang
2020-01-21 11:09                         ` Shahaf Shuler
2020-01-22  6:36                           ` Jason Wang
2020-01-21 14:05                       ` Jason Gunthorpe
2020-01-21 14:17                         ` Michael S. Tsirkin
2020-01-22  6:18                           ` Jason Wang
2020-01-20  8:19         ` Jason Wang
2020-01-16 12:42 ` [PATCH 4/5] virtio: introduce a vDPA based transport Jason Wang
2020-01-16 15:38   ` Jason Gunthorpe
2020-01-17  9:32     ` Jason Wang
2020-01-17 14:00       ` Jason Gunthorpe
2020-01-20  7:52         ` Jason Wang
2020-01-17  4:10   ` Randy Dunlap
2020-01-16 12:42 ` [PATCH 5/5] vdpasim: vDPA device simulator Jason Wang
2020-01-16 15:47   ` Jason Gunthorpe [this message]
2020-01-17  9:32     ` Jason Wang
2020-01-17 14:10       ` Jason Gunthorpe
2020-01-20  8:01         ` Jason Wang
2020-02-04  4:19         ` Jason Wang
2020-01-17  4:12   ` Randy Dunlap
2020-01-17  9:35     ` Jason Wang
2020-01-18 18:18   ` kbuild test robot
2020-01-28  3:32   ` Dan Carpenter
2020-02-04  4:07     ` Jason Wang
2020-02-04  8:21   ` Zhu Lingshan
2020-02-04  8:28     ` Jason Wang
2020-02-04 12:52       ` Jason Gunthorpe
2020-02-05  3:14         ` Jason Wang
2020-01-21  8:44 ` [PATCH 0/5] vDPA support Tian, Kevin
2020-01-21  9:39   ` Jason Wang

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