Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934860AbdC3WN1 (ORCPT ); Thu, 30 Mar 2017 18:13:27 -0400 Received: from ale.deltatee.com ([207.54.116.67]:44305 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755186AbdC3WNX (ORCPT ); Thu, 30 Mar 2017 18:13:23 -0400 From: Logan Gunthorpe To: Christoph Hellwig , Sagi Grimberg , "James E.J. Bottomley" , "Martin K. Petersen" , Jens Axboe , Steve Wise , Stephen Bates , Max Gurtovoy , Dan Williams , Keith Busch , Jason Gunthorpe Cc: linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@ml01.01.org, linux-kernel@vger.kernel.org, Logan Gunthorpe Date: Thu, 30 Mar 2017 16:12:39 -0600 Message-Id: <1490911959-5146-9-git-send-email-logang@deltatee.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1490911959-5146-1-git-send-email-logang@deltatee.com> References: <1490911959-5146-1-git-send-email-logang@deltatee.com> X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: hch@lst.de, sagi@grimberg.me, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, axboe@kernel.dk, swise@opengridcomputing.com, sbates@raithlin.com, maxg@mellanox.com, dan.j.williams@intel.com, keith.busch@intel.com, jgunthorpe@obsidianresearch.com, linux-nvme@lists.infradead.org, linux-nvdimm@lists.01.org, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, logang@deltatee.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [RFC 8/8] p2pmem: Added char device user interface X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8248 Lines: 335 This creates a userspace interface to use p2pmemory. A user can use mmap on the p2pmem char device to get buffers from the corresponding device. This allows a user to use p2p memory with existing interfaces like RDMA and O_DIRECT. This patch is a bit more controversial because people don't want to expose these interfaces to userspace without more consideration. However, this patch is _very_ useful for expirementing with p2p memory. For example, with this patch, you can test with commands like: ib_write_bw -R --mmap=/dev/p2pmem0 -D 30 or use an fio script like: [rdma-server] rw=read mem=mmapshared:/dev/p2pmem0 ioengine=rdma port=14242 bs=64k size=10G iodepth=2 which would test the bandwidth of RDMA to/from the specified p2p memory. Signed-off-by: Logan Gunthorpe Signed-off-by: Stephen Bates Signed-off-by: Steve Wise --- drivers/memory/p2pmem.c | 184 +++++++++++++++++++++++++++++++++++++++++++++++- include/linux/p2pmem.h | 4 ++ 2 files changed, 186 insertions(+), 2 deletions(-) diff --git a/drivers/memory/p2pmem.c b/drivers/memory/p2pmem.c index 499d42c..129c49c 100644 --- a/drivers/memory/p2pmem.c +++ b/drivers/memory/p2pmem.c @@ -19,14 +19,20 @@ #include #include #include +#include MODULE_DESCRIPTION("Peer 2 Peer Memory Device"); MODULE_VERSION("0.1"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Microsemi Corporation"); +static int max_devices = 16; +module_param(max_devices, int, 0444); +MODULE_PARM_DESC(max_devices, "Maximum number of char devices"); + static struct class *p2pmem_class; static DEFINE_IDA(p2pmem_ida); +static dev_t p2pmem_devt; static struct dentry *p2pmem_debugfs_root; @@ -67,6 +73,144 @@ static struct p2pmem_dev *to_p2pmem(struct device *dev) return container_of(dev, struct p2pmem_dev, dev); } +struct p2pmem_vma { + struct p2pmem_dev *p2pmem_dev; + atomic_t mmap_count; + size_t nr_pages; + + /* Protects the used_pages array */ + struct mutex mutex; + struct page *used_pages[]; +}; + +static void p2pmem_vma_open(struct vm_area_struct *vma) +{ + struct p2pmem_vma *pv = vma->vm_private_data; + + atomic_inc(&pv->mmap_count); +} + +static void p2pmem_vma_free_pages(struct vm_area_struct *vma) +{ + int i; + struct p2pmem_vma *pv = vma->vm_private_data; + + mutex_lock(&pv->mutex); + + for (i = 0; i < pv->nr_pages; i++) { + if (pv->used_pages[i]) { + p2pmem_free_page(pv->p2pmem_dev, pv->used_pages[i]); + pv->used_pages[i] = NULL; + } + } + + mutex_unlock(&pv->mutex); +} + +static void p2pmem_vma_close(struct vm_area_struct *vma) +{ + struct p2pmem_vma *pv = vma->vm_private_data; + + if (!atomic_dec_and_test(&pv->mmap_count)) + return; + + p2pmem_vma_free_pages(vma); + + dev_dbg(&pv->p2pmem_dev->dev, "vma close"); + kfree(pv); +} + +static int p2pmem_vma_fault(struct vm_fault *vmf) +{ + struct p2pmem_vma *pv = vmf->vma->vm_private_data; + unsigned int pg_idx; + struct page *pg; + pfn_t pfn; + int rc; + + if (!pv->p2pmem_dev->alive) + return VM_FAULT_SIGBUS; + + pg_idx = (vmf->address - vmf->vma->vm_start) / PAGE_SIZE; + + mutex_lock(&pv->mutex); + + if (pv->used_pages[pg_idx]) + pg = pv->used_pages[pg_idx]; + else + pg = p2pmem_alloc_page(pv->p2pmem_dev); + + if (!pg) + return VM_FAULT_OOM; + + pv->used_pages[pg_idx] = pg; + + pfn = phys_to_pfn_t(page_to_phys(pg), PFN_DEV | PFN_MAP); + rc = vm_insert_mixed(vmf->vma, vmf->address, pfn); + + mutex_unlock(&pv->mutex); + + if (rc == -ENOMEM) + return VM_FAULT_OOM; + if (rc < 0 && rc != -EBUSY) + return VM_FAULT_SIGBUS; + + return VM_FAULT_NOPAGE; +} + +const struct vm_operations_struct p2pmem_vmops = { + .open = p2pmem_vma_open, + .close = p2pmem_vma_close, + .fault = p2pmem_vma_fault, +}; + +static int p2pmem_open(struct inode *inode, struct file *filp) +{ + struct p2pmem_dev *p; + + p = container_of(inode->i_cdev, struct p2pmem_dev, cdev); + filp->private_data = p; + p->inode = inode; + + return 0; +} + +static int p2pmem_mmap(struct file *filp, struct vm_area_struct *vma) +{ + struct p2pmem_dev *p = filp->private_data; + struct p2pmem_vma *pv; + size_t nr_pages = (vma->vm_end - vma->vm_start) / PAGE_SIZE; + + if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) { + dev_warn(&p->dev, "mmap failed: can't create private mapping\n"); + return -EINVAL; + } + + dev_dbg(&p->dev, "Allocating mmap with %zd pages.\n", nr_pages); + + pv = kzalloc(sizeof(*pv) + sizeof(pv->used_pages[0]) * nr_pages, + GFP_KERNEL); + if (!pv) + return -ENOMEM; + + mutex_init(&pv->mutex); + pv->nr_pages = nr_pages; + pv->p2pmem_dev = p; + atomic_set(&pv->mmap_count, 1); + + vma->vm_private_data = pv; + vma->vm_ops = &p2pmem_vmops; + vma->vm_flags |= VM_MIXEDMAP; + + return 0; +} + +static const struct file_operations p2pmem_fops = { + .owner = THIS_MODULE, + .open = p2pmem_open, + .mmap = p2pmem_mmap, +}; + static void p2pmem_percpu_release(struct percpu_ref *ref) { struct p2pmem_dev *p = container_of(ref, struct p2pmem_dev, ref); @@ -114,10 +258,23 @@ struct remove_callback { static void p2pmem_remove(struct p2pmem_dev *p) { struct remove_callback *remove_call, *tmp; + struct vm_area_struct *vma; p->alive = false; list_for_each_entry_safe(remove_call, tmp, &p->remove_list, list) remove_call->callback(remove_call->context); + + if (!p->inode) + return; + + unmap_mapping_range(p->inode->i_mapping, 0, 0, 1); + + i_mmap_lock_write(p->inode->i_mapping); + vma_interval_tree_foreach(vma, &p->inode->i_mapping->i_mmap, 0, + ULONG_MAX) { + p2pmem_vma_free_pages(vma); + } + i_mmap_unlock_write(p->inode->i_mapping); } /** @@ -147,6 +304,10 @@ struct p2pmem_dev *p2pmem_create(struct device *parent) p->dev.parent = parent; p->dev.release = p2pmem_release; + cdev_init(&p->cdev, &p2pmem_fops); + p->cdev.owner = THIS_MODULE; + p->cdev.kobj.parent = &p->dev.kobj; + p->id = ida_simple_get(&p2pmem_ida, 0, 0, GFP_KERNEL); if (p->id < 0) { rc = p->id; @@ -154,6 +315,7 @@ struct p2pmem_dev *p2pmem_create(struct device *parent) } dev_set_name(&p->dev, "p2pmem%d", p->id); + p->dev.devt = MKDEV(MAJOR(p2pmem_devt), p->id); p->pool = gen_pool_create(PAGE_SHIFT, nid); if (!p->pool) { @@ -177,14 +339,20 @@ struct p2pmem_dev *p2pmem_create(struct device *parent) setup_debugfs(p); } - rc = device_add(&p->dev); + rc = cdev_add(&p->cdev, p->dev.devt, 1); if (rc) goto err_id; - dev_info(&p->dev, "registered"); + rc = device_add(&p->dev); + if (rc) + goto err_cdev; + dev_info(&p->dev, "registered"); return p; +err_cdev: + cdev_del(&p->cdev); + p2pmem_remove(p); err_id: ida_simple_remove(&p2pmem_ida, p->id); err_free: @@ -206,6 +374,7 @@ void p2pmem_unregister(struct p2pmem_dev *p) dev_info(&p->dev, "unregistered"); device_del(&p->dev); + cdev_del(&p->cdev); p2pmem_remove(p); ida_simple_remove(&p2pmem_ida, p->id); put_device(&p->dev); @@ -495,21 +664,32 @@ EXPORT_SYMBOL(p2pmem_put); static int __init p2pmem_init(void) { + int rc; + p2pmem_class = class_create(THIS_MODULE, "p2pmem"); if (IS_ERR(p2pmem_class)) return PTR_ERR(p2pmem_class); + rc = alloc_chrdev_region(&p2pmem_devt, 0, max_devices, "iopmemc"); + if (rc) + goto err_chrdev; + p2pmem_debugfs_root = debugfs_create_dir("p2pmem", NULL); if (!p2pmem_debugfs_root) pr_info("could not create debugfs entry, continuing\n"); return 0; + +err_chrdev: + class_destroy(p2pmem_class); + return rc; } module_init(p2pmem_init); static void __exit p2pmem_exit(void) { debugfs_remove_recursive(p2pmem_debugfs_root); + unregister_chrdev_region(p2pmem_devt, max_devices); class_destroy(p2pmem_class); pr_info(KBUILD_MODNAME ": unloaded.\n"); diff --git a/include/linux/p2pmem.h b/include/linux/p2pmem.h index 9365b02..aeee60d 100644 --- a/include/linux/p2pmem.h +++ b/include/linux/p2pmem.h @@ -18,6 +18,7 @@ #include #include +#include struct p2pmem_dev { struct device dev; @@ -32,6 +33,9 @@ struct p2pmem_dev { struct mutex remove_mutex; /* protects the remove callback list */ struct list_head remove_list; + + struct cdev cdev; + struct inode *inode; }; #ifdef CONFIG_P2PMEM -- 2.1.4