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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 5F8D2C43603 for ; Fri, 13 Dec 2019 21:23:49 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E248221655 for ; Fri, 13 Dec 2019 21:23:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E248221655 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 20D331011369A; Fri, 13 Dec 2019 09:50:54 -0800 (PST) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=192.55.52.115; helo=mga14.intel.com; envelope-from=sean.j.christopherson@intel.com; receiver= Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 4578310113697 for ; Fri, 13 Dec 2019 09:50:51 -0800 (PST) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Dec 2019 09:47:03 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,309,1571727600"; d="scan'208";a="296989821" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by orsmga001.jf.intel.com with ESMTP; 13 Dec 2019 09:47:02 -0800 Date: Fri, 13 Dec 2019 09:47:02 -0800 From: Sean Christopherson To: Barret Rhoden Subject: Re: [PATCH v5 1/2] mm: make dev_pagemap_mapping_shift() externally visible Message-ID: <20191213174702.GB31552@linux.intel.com> References: <20191212182238.46535-1-brho@google.com> <20191212182238.46535-2-brho@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191212182238.46535-2-brho@google.com> User-Agent: Mutt/1.5.24 (2015-08-30) Message-ID-Hash: A6SUUB2EWN6Y7UW5ZIARIIFZBE7TB3YL X-Message-ID-Hash: A6SUUB2EWN6Y7UW5ZIARIIFZBE7TB3YL X-MailFrom: sean.j.christopherson@intel.com X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Paolo Bonzini , David Hildenbrand , Alexander Duyck , linux-nvdimm@lists.01.org, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, jason.zeng@intel.com X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Dec 12, 2019 at 01:22:37PM -0500, Barret Rhoden wrote: > KVM has a use case for determining the size of a dax mapping. > > The KVM code has easy access to the address and the mm, and > dev_pagemap_mapping_shift() needs only those parameters. It was > deriving them from page and vma. This commit changes those parameters > from (page, vma) to (address, mm). > > Signed-off-by: Barret Rhoden > Reviewed-by: David Hildenbrand > Acked-by: Dan Williams > --- > include/linux/mm.h | 3 +++ > mm/memory-failure.c | 38 +++----------------------------------- > mm/util.c | 34 ++++++++++++++++++++++++++++++++++ > 3 files changed, 40 insertions(+), 35 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index a2adf95b3f9c..bfd1882dd5c6 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1013,6 +1013,9 @@ static inline bool is_pci_p2pdma_page(const struct page *page) > #define page_ref_zero_or_close_to_overflow(page) \ > ((unsigned int) page_ref_count(page) + 127u <= 127u) > > +unsigned long dev_pagemap_mapping_shift(unsigned long address, > + struct mm_struct *mm); > + > static inline void get_page(struct page *page) > { > page = compound_head(page); > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 3151c87dff73..bafa464c8290 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -261,40 +261,6 @@ void shake_page(struct page *p, int access) > } > EXPORT_SYMBOL_GPL(shake_page); > > -static unsigned long dev_pagemap_mapping_shift(struct page *page, > - struct vm_area_struct *vma) > -{ > - unsigned long address = vma_address(page, vma); > - pgd_t *pgd; > - p4d_t *p4d; > - pud_t *pud; > - pmd_t *pmd; > - pte_t *pte; > - > - pgd = pgd_offset(vma->vm_mm, address); > - if (!pgd_present(*pgd)) > - return 0; > - p4d = p4d_offset(pgd, address); > - if (!p4d_present(*p4d)) > - return 0; > - pud = pud_offset(p4d, address); > - if (!pud_present(*pud)) > - return 0; > - if (pud_devmap(*pud)) > - return PUD_SHIFT; > - pmd = pmd_offset(pud, address); > - if (!pmd_present(*pmd)) > - return 0; > - if (pmd_devmap(*pmd)) > - return PMD_SHIFT; > - pte = pte_offset_map(pmd, address); > - if (!pte_present(*pte)) > - return 0; > - if (pte_devmap(*pte)) > - return PAGE_SHIFT; > - return 0; > -} > - > /* > * Failure handling: if we can't find or can't kill a process there's > * not much we can do. We just print a message and ignore otherwise. > @@ -324,7 +290,9 @@ static void add_to_kill(struct task_struct *tsk, struct page *p, > } > tk->addr = page_address_in_vma(p, vma); > if (is_zone_device_page(p)) > - tk->size_shift = dev_pagemap_mapping_shift(p, vma); > + tk->size_shift = > + dev_pagemap_mapping_shift(vma_address(page, vma), > + vma->vm_mm); > else > tk->size_shift = compound_order(compound_head(p)) + PAGE_SHIFT; > > diff --git a/mm/util.c b/mm/util.c > index 3ad6db9a722e..59984e6b40ab 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -901,3 +901,37 @@ int memcmp_pages(struct page *page1, struct page *page2) > kunmap_atomic(addr1); > return ret; > } > + > +unsigned long dev_pagemap_mapping_shift(unsigned long address, > + struct mm_struct *mm) > +{ > + pgd_t *pgd; > + p4d_t *p4d; > + pud_t *pud; > + pmd_t *pmd; > + pte_t *pte; > + > + pgd = pgd_offset(mm, address); > + if (!pgd_present(*pgd)) > + return 0; > + p4d = p4d_offset(pgd, address); > + if (!p4d_present(*p4d)) > + return 0; > + pud = pud_offset(p4d, address); > + if (!pud_present(*pud)) > + return 0; > + if (pud_devmap(*pud)) > + return PUD_SHIFT; > + pmd = pmd_offset(pud, address); > + if (!pmd_present(*pmd)) > + return 0; > + if (pmd_devmap(*pmd)) > + return PMD_SHIFT; > + pte = pte_offset_map(pmd, address); > + if (!pte_present(*pte)) > + return 0; > + if (pte_devmap(*pte)) > + return PAGE_SHIFT; > + return 0; > +} > +EXPORT_SYMBOL_GPL(dev_pagemap_mapping_shift); This is basically a rehash of lookup_address_in_pgd(), and doesn't provide exactly what KVM needs. E.g. KVM works with levels instead of shifts, and it would be nice to provide the pte so that KVM can sanity check that the pfn from this walk matches the pfn it plans on mapping. Instead of exporting dev_pagemap_mapping_shift(), what about relacing it with a patch to introduce lookup_address_mm() and export that? dev_pagemap_mapping_shift() could then wrap the new helper (if you want), and KVM could do lookup_address_mm() for querying the size of ZONE_DEVICE pages. _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org