From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v5 2/5] virtio-pmem: Add virtio pmem driver Date: Wed, 10 Apr 2019 14:24:26 +0200 Message-ID: <20190410142426.5bf0d9a4.cohuck__24676.4136639953$1554899123$gmane$org@redhat.com> References: <20190410040826.24371-1-pagupta@redhat.com> <20190410040826.24371-3-pagupta@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190410040826.24371-3-pagupta@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Pankaj Gupta Cc: jack@suse.cz, kvm@vger.kernel.org, mst@redhat.com, david@fromorbit.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, adilger.kernel@dilger.ca, zwisler@kernel.org, aarcange@redhat.com, dave.jiang@intel.com, linux-nvdimm@lists.01.org, vishal.l.verma@intel.com, willy@infradead.org, hch@infradead.org, linux-acpi@vger.kernel.org, jmoyer@redhat.com, linux-ext4@vger.kernel.org, lenb@kernel.org, kilobyte@angband.pl, riel@surriel.com, yuval.shaia@oracle.com, stefanha@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, lcapitulino@redhat.com, nilal@redhat.com, tytso@mit.edu, xiaoguangrong.eric@gmail.com, darrick.wong@oracle.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, imammedo@redhat.com List-Id: virtualization@lists.linuxfoundation.org On Wed, 10 Apr 2019 09:38:22 +0530 Pankaj Gupta wrote: > 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 > --- > 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 > +#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) IMHO, you don't gain much by splitting off this function... > +{ > + 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); I'm personally not a fan of chained assignments... I think I'd just drop the 'vq' variable and operate on vpmem->req_vq directly. > + > + 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", Maybe s/config disabled/config access disabled/ ? That seems to be the more common message. > + __func__); > + return -EINVAL; > + } > + > + vdev->priv = vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), > + GFP_KERNEL); Here, the vpmem variable makes sense for convenience, but I'm again not a fan of the chaining :) > + 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); And here :) > + 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); Isn't it clear that this parent chain will always end up at &vdev->dev? Maybe simply set ->provider_data to vdev directly? (Does it need to grab a reference count of the device, BTW?) > + > + if (!nd_region) > + goto out_nd; Probably better to do this check before you access nd_region's members :) > + > + 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); I haven't followed this around the nvdimm code, but is the nd_region you created during probe cleaned up automatically, or would you need to do something here? > + vdev->config->del_vqs(vdev); > + vdev->config->reset(vdev); > + kfree(vpmem); You allocated vpmem via devm_kzalloc; isn't it freed automatically on remove? > +} > + > +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"); Only looked at this from the general virtio driver angle; seems fine apart from some easy-to-fix issues and some personal style preference things.