Re: [PATCH v9 2/7] virtio-pmem: Add virtio pmem driver

David Hildenbrand
2019-05-15T20:46:34Z

> + vpmem->vdev = vdev;
> + vdev->priv = vpmem;
> + err = init_vq(vpmem);
> + if (err) {
> + dev_err(&vdev->dev, "failed to initialize virtio pmem vq's\n");
> + goto out_err;
> + }
> +
> + virtio_cread(vpmem->vdev, struct virtio_pmem_config,
> + start, &vpmem->start);
> + virtio_cread(vpmem->vdev, struct virtio_pmem_config,
> + size, &vpmem->size);
> +
> + res.start = vpmem->start;
> + res.end = vpmem->start + vpmem->size-1;

nit: " - 1;"

> + vpmem->nd_desc.provider_name = "virtio-pmem";
> + vpmem->nd_desc.module = THIS_MODULE;
> +
> + vpmem->nvdimm_bus = nvdimm_bus_register(&vdev->dev,
> + &vpmem->nd_desc);
> + if (!vpmem->nvdimm_bus) {
> + dev_err(&vdev->dev, "failed to register device with nvdimm_bus\n");
> + err = -ENXIO;
> + goto out_vq;
> + }
> +
> + dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus);
> +
> + ndr_desc.res = &res;
> + ndr_desc.numa_node = nid;
> + ndr_desc.flush = async_pmem_flush;
> + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
> + set_bit(ND_REGION_ASYNC, &ndr_desc.flags);
> + nd_region = nvdimm_pmem_region_create(vpmem->nvdimm_bus, &ndr_desc);
> + if (!nd_region) {
> + dev_err(&vdev->dev, "failed to create nvdimm region\n");
> + err = -ENXIO;
> + goto out_nd;
> + }
> + nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent);
> + return 0;
> +out_nd:
> + nvdimm_bus_unregister(vpmem->nvdimm_bus);
> +out_vq:
> + vdev->config->del_vqs(vdev);
> +out_err:
> + return err;
> +}
> +
> +static void virtio_pmem_remove(struct virtio_device *vdev)
> +{
> + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev);
> +
> + nvdimm_bus_unregister(nvdimm_bus);
> + vdev->config->del_vqs(vdev);
> + vdev->config->reset(vdev);
> +}
> +
> +static struct virtio_driver virtio_pmem_driver = {
> + .driver.name = KBUILD_MODNAME,
> + .driver.owner = THIS_MODULE,
> + .id_table = id_table,
> + .probe = virtio_pmem_probe,
> + .remove = virtio_pmem_remove,
> +};
> +
> +module_virtio_driver(virtio_pmem_driver);
> +MODULE_DEVICE_TABLE(virtio, id_table);
> +MODULE_DESCRIPTION("Virtio pmem driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/nvdimm/virtio_pmem.h b/drivers/nvdimm/virtio_pmem.h
> new file mode 100644
> index 000000000000..ab1da877575d
> --- /dev/null
> +++ b/drivers/nvdimm/virtio_pmem.h
> @@ -0,0 +1,60 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * virtio_pmem.h: virtio pmem Driver
> + *
> + * Discovers persistent memory range information
> + * from host and provides a virtio based flushing
> + * interface.
> + **/
> +
> +#ifndef _LINUX_VIRTIO_PMEM_H
> +#define _LINUX_VIRTIO_PMEM_H
> +
> +#include <linux/virtio_ids.h>
> +#include <linux/module.h>
> +#include <linux/virtio_config.h>
> +#include <uapi/linux/virtio_pmem.h>
> +#include <linux/libnvdimm.h>
> +#include <linux/spinlock.h>
> +
> +struct virtio_pmem_request {
> + /* Host return status corresponding to flush request */
> + int ret;
> +
> + /* command name*/
> + char name[16];

So ... why are we sending string commands and expect native-endianess
integers and don't define a proper request/response structure + request
types in include/uapi/linux/virtio_pmem.h like

struct virtio_pmem_resp {
__virtio32 ret;
}

#define VIRTIO_PMEM_REQ_TYPE_FLUSH 1
struct virtio_pmem_req {
__virtio16 type;
}

... and this way we also define a proper endianess format for exchange
and keep it extensible

@MST, what's your take on this?

--

Thanks,

David / dhildenb