From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B015C04A6B for ; Fri, 10 May 2019 23:33:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 169A3217F5 for ; Fri, 10 May 2019 23:33:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="prtx5XbQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728201AbfEJXdp (ORCPT ); Fri, 10 May 2019 19:33:45 -0400 Received: from mail-oi1-f195.google.com ([209.85.167.195]:45485 "EHLO mail-oi1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728154AbfEJXdn (ORCPT ); Fri, 10 May 2019 19:33:43 -0400 Received: by mail-oi1-f195.google.com with SMTP id w144so198764oie.12 for ; Fri, 10 May 2019 16:33:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WC/y1DmHB2Y90knG08MAWJGLd/iKaXtu4mQo0QQg32o=; b=prtx5XbQoKn8R8zrPANnGGghcOCZK+wRPFO9hQpMhQaWx9/y/5msAKm524s/8jfR4q Hy/plrFCxwPLklnjRg1ytI1vkn65dKxxuODtQeQONgGnDyY1Qeyz0ulF0k6we7eJvilt tmVlP80ebYIRcJwK89TR50H36szz+HZnzK7WWoKiff6yLgse0PR4bCCx+krMuh/OcsHY rTLVV48h5/TQ1ELvZZDMwiGcklzyIYGSPlmmucHXjV/zIDskI4WdEUyDfHwtO5v/HA5K wzM6gR/i/MF76pXW0PLzzNQE/aQ80Tklyd5SMmPr2Rqn7ds79bCo7+Dp3zNj56KtP/n1 rr+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WC/y1DmHB2Y90knG08MAWJGLd/iKaXtu4mQo0QQg32o=; b=P+/tgMLu91D58nldJIIi8f/mDnjUQyKVsL0IxQIQ6pa7Tbv1bQ0lcL+Wu2gvz/HyfW YvyVyDDQc0lCxforRcE5v6XxuXTeOSDrUBoZmCau3FXiMU4GgZLwLhVkDebUz38kteDj DfBUEaFYxYtl8N/nqCxofyaK4lzxsk8Ok0wpGYhL51zrwxTJhEtI94CV8TfwyGt6aVp4 iboj7cZvap8LK9vdMNZSqllPNwyWZ+UVm6T0Z4LTPLFo2sKp6ch4ZytlTYsrA7u2Pltv Zv8XhDCv9Tkg6T8rHN9MZWuRzkS8tNqVCZZSP6j8IxTMhE+rSW4LHOnXX+ooSodvoFGl l5Xw== X-Gm-Message-State: APjAAAVyPpejdrf2ufMlmTiekRhvsom876Zq2b+RN6cz2tY4Pls0XYrW wOcEyC/AKH98d6ETmCVuJkA9sMxUDyZkcOw2geMf2A== X-Google-Smtp-Source: APXvYqy3hU8IrTm8PSkpuEnPK36JXZdIT/LmyaieX/IDEIUp9CvxH/SS4vBmVUBtvUxwooicCRs3MOkHKX/DpSGnAGY= X-Received: by 2002:aca:de57:: with SMTP id v84mr7193950oig.149.1557531222870; Fri, 10 May 2019 16:33:42 -0700 (PDT) MIME-Version: 1.0 References: <20190426050039.17460-1-pagupta@redhat.com> <20190426050039.17460-3-pagupta@redhat.com> <2066697253.27249896.1557314351749.JavaMail.zimbra@redhat.com> In-Reply-To: <2066697253.27249896.1557314351749.JavaMail.zimbra@redhat.com> From: Dan Williams Date: Fri, 10 May 2019 16:33:31 -0700 Message-ID: Subject: Re: [Qemu-devel] [PATCH v7 2/6] virtio-pmem: Add virtio pmem driver To: Pankaj Gupta Cc: cohuck@redhat.com, Jan Kara , KVM list , Jason Wang , david , "Michael S. Tsirkin" , Qemu Developers , virtualization@lists.linux-foundation.org, Andreas Dilger , Ross Zwisler , Andrea Arcangeli , Dave Jiang , linux-nvdimm , Vishal L Verma , David Hildenbrand , Matthew Wilcox , Christoph Hellwig , Linux ACPI , jmoyer , linux-ext4 , Len Brown , kilobyte@angband.pl, Rik van Riel , yuval shaia , Stefan Hajnoczi , Paolo Bonzini , lcapitulino@redhat.com, Kevin Wolf , Nitesh Narayan Lal , "Theodore Ts'o" , Xiao Guangrong , "Darrick J. Wong" , "Rafael J. Wysocki" , Linux Kernel Mailing List , linux-xfs , linux-fsdevel , Igor Mammedov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 8, 2019 at 4:19 AM Pankaj Gupta wrote: > > > Hi Dan, > > Thank you for the review. Please see my reply inline. > > > > > Hi Pankaj, > > > > Some minor file placement comments below. > > Sure. > > > > > On Thu, Apr 25, 2019 at 10:02 PM 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 | 114 +++++++++++++++++++++++++++++ > > > drivers/virtio/Kconfig | 10 +++ > > > drivers/virtio/Makefile | 1 + > > > drivers/virtio/pmem.c | 118 +++++++++++++++++++++++++++++++ > > > include/linux/virtio_pmem.h | 60 ++++++++++++++++ > > > include/uapi/linux/virtio_ids.h | 1 + > > > include/uapi/linux/virtio_pmem.h | 10 +++ > > > 7 files changed, 314 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/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > > > new file mode 100644 > > > index 000000000000..66b582f751a3 > > > --- /dev/null > > > +++ b/drivers/nvdimm/virtio_pmem.c > > > @@ -0,0 +1,114 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +/* > > > + * virtio_pmem.c: Virtio pmem Driver > > > + * > > > + * Discovers persistent memory range information > > > + * from host and provides a virtio based flushing > > > + * interface. > > > + */ > > > +#include > > > +#include "nd.h" > > > + > > > + /* The interrupt handler */ > > > +void host_ack(struct virtqueue *vq) > > > +{ > > > + unsigned int len; > > > + unsigned long flags; > > > + struct virtio_pmem_request *req, *req_buf; > > > + struct virtio_pmem *vpmem = vq->vdev->priv; > > > + > > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > > + while ((req = virtqueue_get_buf(vq, &len)) != NULL) { > > > + req->done = true; > > > + wake_up(&req->host_acked); > > > + > > > + if (!list_empty(&vpmem->req_list)) { > > > + req_buf = list_first_entry(&vpmem->req_list, > > > + struct virtio_pmem_request, list); > > > + list_del(&vpmem->req_list); > > > + req_buf->wq_buf_avail = true; > > > + wake_up(&req_buf->wq_buf); > > > + } > > > + } > > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > > +} > > > +EXPORT_SYMBOL_GPL(host_ack); > > > + > > > + /* The request submission function */ > > > +int virtio_pmem_flush(struct nd_region *nd_region) > > > +{ > > > + int err; > > > + unsigned long flags; > > > + struct scatterlist *sgs[2], sg, ret; > > > + struct virtio_device *vdev = nd_region->provider_data; > > > + struct virtio_pmem *vpmem = vdev->priv; > > > + struct virtio_pmem_request *req; > > > + > > > + might_sleep(); > > > + req = kmalloc(sizeof(*req), GFP_KERNEL); > > > + if (!req) > > > + return -ENOMEM; > > > + > > > + req->done = req->wq_buf_avail = false; > > > + strcpy(req->name, "FLUSH"); > > > + init_waitqueue_head(&req->host_acked); > > > + init_waitqueue_head(&req->wq_buf); > > > + sg_init_one(&sg, req->name, strlen(req->name)); > > > + sgs[0] = &sg; > > > + sg_init_one(&ret, &req->ret, sizeof(req->ret)); > > > + sgs[1] = &ret; > > > + > > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > > + err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req, GFP_ATOMIC); > > > + if (err) { > > > + dev_err(&vdev->dev, "failed to send command to virtio pmem > > > device\n"); > > > + > > > + list_add_tail(&vpmem->req_list, &req->list); > > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > > + > > > + /* When host has read buffer, this completes via host_ack > > > */ > > > + wait_event(req->wq_buf, req->wq_buf_avail); > > > + spin_lock_irqsave(&vpmem->pmem_lock, flags); > > > + } > > > + err = virtqueue_kick(vpmem->req_vq); > > > + spin_unlock_irqrestore(&vpmem->pmem_lock, flags); > > > + > > > + if (!err) { > > > + err = -EIO; > > > + goto ret; > > > + } > > > + /* When host has read buffer, this completes via host_ack */ > > > + wait_event(req->host_acked, req->done); > > > + err = req->ret; > > > +ret: > > > + kfree(req); > > > + return err; > > > +}; > > > + > > > + /* The asynchronous flush callback function */ > > > +int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) > > > +{ > > > + int rc = 0; > > > + > > > + /* Create child bio for asynchronous flush and chain with > > > + * parent bio. Otherwise directly call nd_region flush. > > > + */ > > > + if (bio && bio->bi_iter.bi_sector != -1) { > > > + struct bio *child = bio_alloc(GFP_ATOMIC, 0); > > > + > > > + if (!child) > > > + return -ENOMEM; > > > + bio_copy_dev(child, bio); > > > + child->bi_opf = REQ_PREFLUSH; > > > + child->bi_iter.bi_sector = -1; > > > + bio_chain(child, bio); > > > + submit_bio(child); > > > + } else { > > > + if (virtio_pmem_flush(nd_region)) > > > + rc = -EIO; > > > + } > > > + > > > + return rc; > > > +}; > > > +EXPORT_SYMBOL_GPL(async_pmem_flush); > > > +MODULE_LICENSE("GPL"); > > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > > > index 35897649c24f..9f634a2ed638 100644 > > > --- a/drivers/virtio/Kconfig > > > +++ b/drivers/virtio/Kconfig > > > @@ -42,6 +42,16 @@ config VIRTIO_PCI_LEGACY > > > > > > If unsure, say Y. > > > > > > +config VIRTIO_PMEM > > > + tristate "Support for virtio pmem driver" > > > + depends on VIRTIO > > > + depends on LIBNVDIMM > > > + help > > > + This driver provides support for virtio based flushing interface > > > + for persistent memory range. > > > + > > > + If unsure, say M. > > > + > > > config VIRTIO_BALLOON > > > tristate "Virtio balloon driver" > > > depends on VIRTIO > > > diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile > > > index 3a2b5c5dcf46..143ce91eabe9 100644 > > > --- a/drivers/virtio/Makefile > > > +++ b/drivers/virtio/Makefile > > > @@ -6,3 +6,4 @@ virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o > > > virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o > > > obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o > > > obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o > > > +obj-$(CONFIG_VIRTIO_PMEM) += pmem.o ../nvdimm/virtio_pmem.o > > > diff --git a/drivers/virtio/pmem.c b/drivers/virtio/pmem.c > > > new file mode 100644 > > > index 000000000000..309788628e41 > > > --- /dev/null > > > +++ b/drivers/virtio/pmem.c > > > > It's not clear to me why this driver is located in drivers/virtio/ > > Like other VIRTIO drivers, I placed it initially in drivers/virtio directory. > > > > > > @@ -0,0 +1,118 @@ > > > +// 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> > > > > ...especially because it seems to require nvdimm internals. > > > > However I don't see why that header is included. > > Removed. > > > > > In any event lets move this to drivers/nvdimm/virtio.c to live > > alongside the other generic bus provider drivers/nvdimm/e820.c. > > o.k. Makes sense. > > > > > > + > > > +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) > > > +{ > > > + /* single vq */ > > > + vpmem->req_vq = virtio_find_single_vq(vpmem->vdev, > > > + host_ack, "flush_queue"); > > > + if (IS_ERR(vpmem->req_vq)) > > > + return PTR_ERR(vpmem->req_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 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 access disabled\n", > > > + __func__); > > > + return -EINVAL; > > > + } > > > + > > > + vpmem = devm_kzalloc(&vdev->dev, sizeof(*vpmem), GFP_KERNEL); > > > + if (!vpmem) { > > > + err = -ENOMEM; > > > + goto out_err; > > > + } > > > + > > > + vpmem->vdev = vdev; > > > + vdev->priv = vpmem; > > > + 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_register(&vdev->dev, > > > + &vpmem->nd_desc); > > > + if (!vpmem->nvdimm_bus) > > > + 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) > > > + goto out_nd; > > > + nd_region->provider_data = dev_to_virtio > > > + (nd_region->dev.parent->parent); > > > + return 0; > > > +out_nd: > > > + err = -ENXIO; > > > + nvdimm_bus_unregister(vpmem->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 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/include/linux/virtio_pmem.h b/include/linux/virtio_pmem.h > > > new file mode 100644 > > > index 000000000000..ab1da877575d > > > --- /dev/null > > > +++ b/include/linux/virtio_pmem.h > > > > Why is this a global header? > > This is where other virtio driver headers are also placed. > I think this is to access uapi config file in : > > ./include/uapi/linux/virtio_pmem.h > > Is it okay if we keep 'virtio_pmem.h' in global header? No, I don't think so. While virtio_console.h and virtio_net.h make sense as global headers because they are consumed from multiple drivers, there is no need for virtio_caif.h, for example, to be a global header. I see no practical reason that the private details of virtio_pmem.h need to be made available outside of the virtio_pmem.c consumer.