Re: [PATCH v5 2/5] virtio-pmem: Add virtio pmem driver

This patch adds virtio-pmem driver for KVM guest. Guest reads the persistent memory range information from Qemu over VIRTIO and registers it on nvdimm_bus. It also creates a nd_region object with the persistent memory range information so that existing 'nvdimm/pmem' driver can reserve this into system memory map. This way 'virtio-pmem' driver uses existing functionality of pmem driver to register persistent memory compatible for DAX capable filesystems. This also provides function to perform guest flush over VIRTIO from 'pmem' driver when userspace performs flush on DAX memory range. Signed-off-by: Pankaj Gupta <pagupta(a)redhat.com&gt; --- drivers/nvdimm/virtio_pmem.c | 88 ++++++++++++++++++++++ drivers/virtio/Kconfig | 10 +++ drivers/virtio/Makefile | 1 + drivers/virtio/pmem.c | 124 +++++++++++++++++++++++++++++++ include/linux/virtio_pmem.h | 60 +++++++++++++++ include/uapi/linux/virtio_ids.h | 1 + include/uapi/linux/virtio_pmem.h | 10 +++ 7 files changed, 294 insertions(+) create mode 100644 drivers/nvdimm/virtio_pmem.c create mode 100644 drivers/virtio/pmem.c create mode 100644 include/linux/virtio_pmem.h create mode 100644 include/uapi/linux/virtio_pmem.h

diff --git a/drivers/virtio/pmem.c b/drivers/virtio/pmem.c new file mode 100644 index 000000000000..cc9de9589d56 --- /dev/null +++ b/drivers/virtio/pmem.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * virtio_pmem.c: Virtio pmem Driver + * + * Discovers persistent memory range information + * from host and registers the virtual pmem device + * with libnvdimm core. + */ +#include <linux/virtio_pmem.h> +#include <../../drivers/nvdimm/nd.h> + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_PMEM, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + + /* Initialize virt queue */ +static int init_vq(struct virtio_pmem *vpmem)

+{ + struct virtqueue *vq; + + /* single vq */ + vpmem->req_vq = vq = virtio_find_single_vq(vpmem->vdev, + host_ack, "flush_queue"); + if (IS_ERR(vq)) + return PTR_ERR(vq);

+ + spin_lock_init(&vpmem->pmem_lock); + INIT_LIST_HEAD(&vpmem->req_list); + + return 0; +}; + +static int virtio_pmem_probe(struct virtio_device *vdev) +{ + int err = 0; + struct resource res; + struct virtio_pmem *vpmem; + struct nvdimm_bus *nvdimm_bus; + struct nd_region_desc ndr_desc = {}; + int nid = dev_to_node(&vdev->dev); + struct nd_region *nd_region; + + if (!vdev->config->get) { + dev_err(&vdev->dev, "%s failure: config disabled\n",

+ __func__); + return -EINVAL; + } + + vdev->priv = vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), + GFP_KERNEL);

+ if (!vpmem) { + err = -ENOMEM; + goto out_err; + } + + vpmem->vdev = vdev; + err = init_vq(vpmem); + if (err) + 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; + vpmem->nd_desc.provider_name = "virtio-pmem"; + vpmem->nd_desc.module = THIS_MODULE; + + vpmem->nvdimm_bus = nvdimm_bus = nvdimm_bus_register(&vdev->dev, + &vpmem->nd_desc);

+ if (!nvdimm_bus) + goto out_vq; + + dev_set_drvdata(&vdev->dev, nvdimm_bus); + + ndr_desc.res = &res; + ndr_desc.numa_node = nid; + ndr_desc.flush = virtio_pmem_flush; + set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags); + set_bit(ND_REGION_ASYNC, &ndr_desc.flags); + nd_region = nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc); + nd_region->provider_data = dev_to_virtio + (nd_region->dev.parent->parent);

+ + if (!nd_region) + goto out_nd;

+ + return 0; +out_nd: + err = -ENXIO; + nvdimm_bus_unregister(nvdimm_bus); +out_vq: + vdev->config->del_vqs(vdev); +out_err: + dev_err(&vdev->dev, "failed to register virtio pmem memory\n"); + return err; +} + +static void virtio_pmem_remove(struct virtio_device *vdev) +{ + struct virtio_pmem *vpmem = vdev->priv; + struct nvdimm_bus *nvdimm_bus = dev_get_drvdata(&vdev->dev); + + nvdimm_bus_unregister(nvdimm_bus);

+ vdev->config->del_vqs(vdev); + vdev->config->reset(vdev); + kfree(vpmem);

+} + +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");