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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 57610CA9EBB for ; Wed, 23 Oct 2019 19:55:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1158421A4A for ; Wed, 23 Oct 2019 19:55:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="NSjudj3A" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1158421A4A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B86616B0006; Wed, 23 Oct 2019 15:55:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B16A86B0007; Wed, 23 Oct 2019 15:55:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9D6D36B0008; Wed, 23 Oct 2019 15:55:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0157.hostedemail.com [216.40.44.157]) by kanga.kvack.org (Postfix) with ESMTP id 7EF4B6B0007 for ; Wed, 23 Oct 2019 15:55:25 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 13996180CDD18 for ; Wed, 23 Oct 2019 19:55:25 +0000 (UTC) X-FDA: 76076103810.13.ants52_4c2e7f1f21d59 X-HE-Tag: ants52_4c2e7f1f21d59 X-Filterd-Recvd-Size: 4276 Received: from hqemgate15.nvidia.com (hqemgate15.nvidia.com [216.228.121.64]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Wed, 23 Oct 2019 19:55:23 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 23 Oct 2019 12:55:31 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Wed, 23 Oct 2019 12:55:21 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 23 Oct 2019 12:55:21 -0700 Received: from HQMAIL109.nvidia.com (172.20.187.15) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 23 Oct 2019 19:55:21 +0000 Received: from HQMAIL109.nvidia.com (172.20.187.15) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 23 Oct 2019 19:55:19 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL109.nvidia.com (172.20.187.15) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 23 Oct 2019 19:55:19 +0000 Received: from rcampbell-dev.nvidia.com (Not Verified[10.110.48.66]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Wed, 23 Oct 2019 12:55:19 -0700 From: Ralph Campbell To: Jerome Glisse , John Hubbard , Christoph Hellwig , Jason Gunthorpe CC: , , , Ralph Campbell Subject: [PATCH v3 2/3] mm/hmm: allow snapshot of the special zero page Date: Wed, 23 Oct 2019 12:55:14 -0700 Message-ID: <20191023195515.13168-3-rcampbell@nvidia.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191023195515.13168-1-rcampbell@nvidia.com> References: <20191023195515.13168-1-rcampbell@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1571860531; bh=EX0bbHxK/iAtD7z9QXzYOmMILzO2RoXi4bWaJEIf6tU=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Type:Content-Transfer-Encoding; b=NSjudj3Amk7YhSyBkxDUUsM8HQ70EkOJRBtGC1+hAxxF4v1egWqIkh/zJZYNC1Q+S 5w56SvKKzQknvOOP/RFwj+bE7kc3iWtQMG3FTES26Tke1g8A+6OhaLeMLWH90BOT3s Sm094urfKBVURhdYRBZX8UUDccf3ZVvEjbnVLpqArlgm2AAkGvlY9fbl3J8Dv/2tOO Yd9QEk80QBSQo3zjh/Sq1YI7oOGscc3SXK6JBnvxSNV7VQ6VIDbEfkBEw2Dtall2fV NVOBYn6SI+RatjZA3KAG5LhyXUK8AmQejMJHQeb+/AgW9UMpg7RmFmnYjescoBEuXi pHIHEZuEDeKSw== 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: If a device driver like nouveau tries to use hmm_range_fault() to access the special shared zero page in system memory, hmm_range_fault() will return -EFAULT and kill the process. Allow hmm_range_fault() to return success (0) when the CPU pagetable entry points to the special shared zero page. page_to_pfn() and pfn_to_page() are defined on the zero page so just handle it like any other page. Signed-off-by: Ralph Campbell Cc: Christoph Hellwig Cc: "J=C3=A9r=C3=B4me Glisse" Cc: Jason Gunthorpe --- mm/hmm.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/hmm.c b/mm/hmm.c index acf7a664b38c..8c96c9ddcae5 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -529,8 +529,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, un= signed long addr, if (unlikely(!hmm_vma_walk->pgmap)) return -EBUSY; } else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) { - *pfn =3D range->values[HMM_PFN_SPECIAL]; - return -EFAULT; + if (!is_zero_pfn(pte_pfn(pte))) { + *pfn =3D range->values[HMM_PFN_SPECIAL]; + return -EFAULT; + } + /* + * Since each architecture defines a struct page for the zero + * page, just fall through and treat it like a normal page. + */ } =20 *pfn =3D hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags; --=20 2.20.1