From patchwork Wed Oct 30 22:49:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11220225 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7FA8214DB for ; Wed, 30 Oct 2019 22:50:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54FF62190F for ; Wed, 30 Oct 2019 22:50:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="NIyNWer0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727797AbfJ3WuA (ORCPT ); Wed, 30 Oct 2019 18:50:00 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:10895 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727721AbfJ3Wtz (ORCPT ); Wed, 30 Oct 2019 18:49:55 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 30 Oct 2019 15:49:58 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Wed, 30 Oct 2019 15:49:52 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Wed, 30 Oct 2019 15:49:52 -0700 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 30 Oct 2019 22:49:52 +0000 Received: from rnnvemgw01.nvidia.com (10.128.109.123) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 30 Oct 2019 22:49:50 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by rnnvemgw01.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Wed, 30 Oct 2019 15:49:50 -0700 From: John Hubbard To: Andrew Morton CC: Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?utf-8?b?QmrDtnJuIFQ=?= =?utf-8?b?w7ZwZWw=?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard Subject: [PATCH 14/19] vfio, mm: pin_longterm_pages (FOLL_PIN) and put_user_page() conversion Date: Wed, 30 Oct 2019 15:49:25 -0700 Message-ID: <20191030224930.3990755-15-jhubbard@nvidia.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191030224930.3990755-1-jhubbard@nvidia.com> References: <20191030224930.3990755-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1572475798; bh=XFjm8RPGYOGaZ8I6ZtqUF2w9I0TfFUQHc/AIPIbYpP8=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=NIyNWer02EnMgKZ9CI4sXwt3Ux9yX4ajp4i5vLHbPveoh8o54s25FzHdtrjaaC5Lf VfosVhiF7ivR2LFLOPHJF45E2C9griCDCZRjJzvkuAwvzJz5oQxrjk1W2FBNv/t05y K9WA8xzVRUfeJTJJYCffPgb4TWKk5kKxW/6FDvZb5VL2fGYJ2P5PWJ7kjzOaJFhGUd XF31UGOtBYD4QLg72qOOtNhZF+bY9kaO0SKRfg3xZP8fvWiZGFBKcdkpbddjVG5j4t 0VemY1URa0sH/nhlOs0AYfqaIAHz3lVPWpgsYIljNs0B6piBSdJ57j0yNKS3kIokdn dWyNgFVoj/U2Q== Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This also fixes one or two likely bugs. 1. Change vfio from get_user_pages(FOLL_LONGTERM), to pin_longterm_pages(), which sets both FOLL_LONGTERM and FOLL_PIN. Note that this is a change in behavior, because the get_user_pages_remote() call was not setting FOLL_LONGTERM, but the new pin_user_pages_remote() call that replaces it, *is* setting FOLL_LONGTERM. It is important to set FOLL_LONGTERM, because the DMA case requires it. Please see the FOLL_PIN documentation in include/linux/mm.h, and Documentation/pin_user_pages.rst for details. 2. Because all FOLL_PIN-acquired pages must be released via put_user_page(), also convert the put_page() call over to put_user_pages(). Note that this effectively changes the code's behavior in vfio_iommu_type1.c: put_pfn(): it now ultimately calls set_page_dirty_lock(), instead of set_page_dirty(). This is probably more accurate. As Christoph Hellwig put it, "set_page_dirty() is only safe if we are dealing with a file backed page where we have reference on the inode it hangs off." [1] [1] https://lore.kernel.org/r/20190723153640.GB720@lst.de Cc: Alex Williamson Signed-off-by: John Hubbard --- drivers/vfio/vfio_iommu_type1.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index d864277ea16f..795e13f3ef08 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -327,9 +327,8 @@ static int put_pfn(unsigned long pfn, int prot) { if (!is_invalid_reserved_pfn(pfn)) { struct page *page = pfn_to_page(pfn); - if (prot & IOMMU_WRITE) - SetPageDirty(page); - put_page(page); + + put_user_pages_dirty_lock(&page, 1, prot & IOMMU_WRITE); return 1; } return 0; @@ -349,11 +348,11 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, down_read(&mm->mmap_sem); if (mm == current->mm) { - ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page, - vmas); + ret = pin_longterm_pages(vaddr, 1, flags, page, vmas); } else { - ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page, - vmas, NULL); + ret = pin_longterm_pages_remote(NULL, mm, vaddr, 1, + flags, page, vmas, + NULL); /* * The lifetime of a vaddr_get_pfn() page pin is * userspace-controlled. In the fs-dax case this could @@ -363,7 +362,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, */ if (ret > 0 && vma_is_fsdax(vmas[0])) { ret = -EOPNOTSUPP; - put_page(page[0]); + put_user_page(page[0]); } } up_read(&mm->mmap_sem);