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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92713C54EE9 for ; Thu, 22 Sep 2022 18:27:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0011B6B0071; Thu, 22 Sep 2022 14:27:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EF1626B0072; Thu, 22 Sep 2022 14:27:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE0FD940007; Thu, 22 Sep 2022 14:27:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id D217F6B0071 for ; Thu, 22 Sep 2022 14:27:40 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 977DFA046F for ; Thu, 22 Sep 2022 18:27:40 +0000 (UTC) X-FDA: 79940554680.06.B799A44 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf06.hostedemail.com (Postfix) with ESMTP id 43C50180021 for ; Thu, 22 Sep 2022 18:27:40 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 588AB63757; Thu, 22 Sep 2022 18:27:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 797E5C433C1; Thu, 22 Sep 2022 18:27:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1663871258; bh=8xWBJ6Sj6BfVo4gfoi/4G8CBQ6Jx/wBwvklLiTjCFyM=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=s69F1omKgr2HrO0nTiXgJhVXfkTHk5wTJUcaIeSmJ0XajGhhyPnrb1bU/nv2iQqnN W3caY/I9YU693aup6abaVXXxOFAj5HnEaV+f+mW+USOTiKdT5VDbo4vuDdzlh8z/UU /aynRJSNuS5OFlAEr08CcXQvqXNzvH82QeBvZ+svaWrWgwoCxBjDhgoTF3HxxGsr2B RHfBlVJJXlQsVDWYkXMPCMh5RNtGs9PdgdSwZvN31BFVKmmjE2hbJ0hP4xDdk1DbDF q+MOFeJrCKHHXBIH9N+ZEVDqAQyriFbate7Mnvp6ebI677UzOy6UvVkYaYR7jIvUKc AWYISuH7tO4Gw== Date: Thu, 22 Sep 2022 13:27:37 -0500 From: Bjorn Helgaas To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , Greg Kroah-Hartman , Dan Williams , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell , Stephen Bates Subject: Re: [PATCH v10 7/8] PCI/P2PDMA: Allow userspace VMA allocations through sysfs Message-ID: <20220922182737.GA1326059@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220922163926.7077-8-logang@deltatee.com> ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=s69F1omK; spf=pass (imf06.hostedemail.com: domain of helgaas@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=helgaas@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663871260; a=rsa-sha256; cv=none; b=jy0d2/F/C2kGGWLtvEhcsxavwIC6Zv8uJjsuQBtb7DfIK7qWWMUpOUF7c0I6TQUB4QOPmL na9XACSRf47Pfee982lXgzil6kZJxXttI1282GwizHG0aZnl9fVBrjW2PO8vCs+l7fcJE4 LFctxAp1NSv4dY0Gn+w5y9cZqH0BlOI= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663871260; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:dkim-signature; bh=hujV+pLrZphSf6wHw7PMT2/FwNfUuvSyfdd2DG/zB6g=; b=DNRNt28ZXOsR38pcNE/QgvsC/0MWjNno2f53p8TIt780hfRjAMAWq3nXDNHNAqXN9YoL9J ar2TIMiXa34LyX2WMuB/x2efTyAtUIs02+PY/tSeGm3PAkeLTSGm6M4EKq6zUlxNiuJAwm CYd17eaiD3q0yZJn5lhDmScmHUMjrcA= Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=s69F1omK; spf=pass (imf06.hostedemail.com: domain of helgaas@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=helgaas@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Rspam-User: X-Stat-Signature: hupkum4p47n18sf1x57zeurhwk1zr5c5 X-Rspamd-Queue-Id: 43C50180021 X-Rspamd-Server: rspam09 X-HE-Tag: 1663871260-762216 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Sep 22, 2022 at 10:39:25AM -0600, Logan Gunthorpe wrote: > Create a sysfs bin attribute called "allocate" under the existing > "p2pmem" group. The only allowable operation on this file is the mmap() > call. > > When mmap() is called on this attribute, the kernel allocates a chunk of > memory from the genalloc and inserts the pages into the VMA. The > dev_pagemap .page_free callback will indicate when these pages are no > longer used and they will be put back into the genalloc. > > On device unbind, remove the sysfs file before the memremap_pages are > cleaned up. This ensures unmap_mapping_range() is called on the files > inode and no new mappings can be created. > > Signed-off-by: Logan Gunthorpe Not sure which tree this should go through, so: Acked-by: Bjorn Helgaas > --- > drivers/pci/p2pdma.c | 124 +++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 124 insertions(+) > > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 4496a7c5c478..a6ed6bbca214 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -89,6 +89,90 @@ static ssize_t published_show(struct device *dev, struct device_attribute *attr, > } > static DEVICE_ATTR_RO(published); > > +static int p2pmem_alloc_mmap(struct file *filp, struct kobject *kobj, > + struct bin_attribute *attr, struct vm_area_struct *vma) > +{ > + struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj)); > + size_t len = vma->vm_end - vma->vm_start; > + struct pci_p2pdma *p2pdma; > + struct percpu_ref *ref; > + unsigned long vaddr; > + void *kaddr; > + int ret; > + > + /* prevent private mappings from being established */ > + if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) { > + pci_info_ratelimited(pdev, > + "%s: fail, attempted private mapping\n", > + current->comm); > + return -EINVAL; > + } > + > + if (vma->vm_pgoff) { > + pci_info_ratelimited(pdev, > + "%s: fail, attempted mapping with non-zero offset\n", > + current->comm); > + return -EINVAL; > + } > + > + rcu_read_lock(); > + p2pdma = rcu_dereference(pdev->p2pdma); > + if (!p2pdma) { > + ret = -ENODEV; > + goto out; > + } > + > + kaddr = (void *)gen_pool_alloc_owner(p2pdma->pool, len, (void **)&ref); > + if (!kaddr) { > + ret = -ENOMEM; > + goto out; > + } > + > + /* > + * vm_insert_page() can sleep, so a reference is taken to mapping > + * such that rcu_read_unlock() can be done before inserting the > + * pages > + */ > + if (unlikely(!percpu_ref_tryget_live_rcu(ref))) { > + ret = -ENODEV; > + goto out_free_mem; > + } > + rcu_read_unlock(); > + > + for (vaddr = vma->vm_start; vaddr < vma->vm_end; vaddr += PAGE_SIZE) { > + ret = vm_insert_page(vma, vaddr, virt_to_page(kaddr)); > + if (ret) { > + gen_pool_free(p2pdma->pool, (uintptr_t)kaddr, len); > + return ret; > + } > + percpu_ref_get(ref); > + put_page(virt_to_page(kaddr)); > + kaddr += PAGE_SIZE; > + len -= PAGE_SIZE; > + } > + > + percpu_ref_put(ref); > + > + return 0; > +out_free_mem: > + gen_pool_free(p2pdma->pool, (uintptr_t)kaddr, len); > +out: > + rcu_read_unlock(); > + return ret; > +} > + > +static struct bin_attribute p2pmem_alloc_attr = { > + .attr = { .name = "allocate", .mode = 0660 }, > + .mmap = p2pmem_alloc_mmap, > + /* > + * Some places where we want to call mmap (ie. python) will check > + * that the file size is greater than the mmap size before allowing > + * the mmap to continue. To work around this, just set the size > + * to be very large. > + */ > + .size = SZ_1T, > +}; > + > static struct attribute *p2pmem_attrs[] = { > &dev_attr_size.attr, > &dev_attr_available.attr, > @@ -96,11 +180,32 @@ static struct attribute *p2pmem_attrs[] = { > NULL, > }; > > +static struct bin_attribute *p2pmem_bin_attrs[] = { > + &p2pmem_alloc_attr, > + NULL, > +}; > + > static const struct attribute_group p2pmem_group = { > .attrs = p2pmem_attrs, > + .bin_attrs = p2pmem_bin_attrs, > .name = "p2pmem", > }; > > +static void p2pdma_page_free(struct page *page) > +{ > + struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page->pgmap); > + struct percpu_ref *ref; > + > + gen_pool_free_owner(pgmap->provider->p2pdma->pool, > + (uintptr_t)page_to_virt(page), PAGE_SIZE, > + (void **)&ref); > + percpu_ref_put(ref); > +} > + > +static const struct dev_pagemap_ops p2pdma_pgmap_ops = { > + .page_free = p2pdma_page_free, > +}; > + > static void pci_p2pdma_release(void *data) > { > struct pci_dev *pdev = data; > @@ -152,6 +257,19 @@ static int pci_p2pdma_setup(struct pci_dev *pdev) > return error; > } > > +static void pci_p2pdma_unmap_mappings(void *data) > +{ > + struct pci_dev *pdev = data; > + > + /* > + * Removing the alloc attribute from sysfs will call > + * unmap_mapping_range() on the inode, teardown any existing userspace > + * mappings and prevent new ones from being created. > + */ > + sysfs_remove_file_from_group(&pdev->dev.kobj, &p2pmem_alloc_attr.attr, > + p2pmem_group.name); > +} > + > /** > * pci_p2pdma_add_resource - add memory for use as p2p memory > * @pdev: the device to add the memory to > @@ -198,6 +316,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, > pgmap->range.end = pgmap->range.start + size - 1; > pgmap->nr_range = 1; > pgmap->type = MEMORY_DEVICE_PCI_P2PDMA; > + pgmap->ops = &p2pdma_pgmap_ops; > > p2p_pgmap->provider = pdev; > p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) - > @@ -209,6 +328,11 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, > goto pgmap_free; > } > > + error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_unmap_mappings, > + pdev); > + if (error) > + goto pages_free; > + > p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); > error = gen_pool_add_owner(p2pdma->pool, (unsigned long)addr, > pci_bus_address(pdev, bar) + offset, > -- > 2.30.2 >