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

[Pankaj Gupta]

> 
> > +   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;"

Sure.

> 
> > +   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

Done the suggested change.

Thank you,
Pankaj

> 
> @MST, what's your take on this?
> 
> 
> --
> 
> Thanks,
> 
> David / dhildenb
>