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

> >> + 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;
> > }
>
> FWIW, I wonder if we should even properly translate return values and
> define types like
>
> VIRTIO_PMEM_RESP_TYPE_OK 0
> VIRTIO_PMEM_RESP_TYPE_EIO 1

Don't think these are required as only failure and success
return types easy to understand.

Thanks,
Pankaj
>
> ..
>
> >
> > #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
>

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