From patchwork Mon Dec 16 22:25:19 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11295833 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 13CED138D for ; Mon, 16 Dec 2019 22:28:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E54DA24680 for ; Mon, 16 Dec 2019 22:28:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="a6UtG6ws" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728371AbfLPW1r (ORCPT ); Mon, 16 Dec 2019 17:27:47 -0500 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:12013 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727974AbfLPWZv (ORCPT ); Mon, 16 Dec 2019 17:25:51 -0500 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 16 Dec 2019 14:25:16 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 16 Dec 2019 14:25:43 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 16 Dec 2019 14:25:43 -0800 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; Mon, 16 Dec 2019 22:25:39 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Mon, 16 Dec 2019 22:25:39 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Mon, 16 Dec 2019 14:25:39 -0800 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 , "Jason Gunthorpe" Subject: [PATCH v11 07/25] vfio: fix FOLL_LONGTERM use, simplify get_user_pages_remote() call Date: Mon, 16 Dec 2019 14:25:19 -0800 Message-ID: <20191216222537.491123-8-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191216222537.491123-1-jhubbard@nvidia.com> References: <20191216222537.491123-1-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=1576535116; bh=Q+D0QrBLJsS/IUxYkIZE7Q9OtYhC1beEAlqv13tUlJU=; 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=a6UtG6wsF7sRZ84TNiXh+8fAQgAcz9GyguF0P+WBrEnBY3raawfHoc0hdv7zUw0BY qpQfY7wVtd/iuajGO0al/sjV3pWBys2/RIPo7QvlufgqEp2o8WjXsd8tHured5b/s/ rR51ZVfwRU3Op5ghOs7TPj2gqyA5nvuknjgBIwdNlv/nZtijJA1KeG7xSKVb70IiTC BE7IwUgjLfUBuP0ZJW/pUhNsrykjxpnB88M63Zh3945AZ+9O/NGJ8j0MA9N8izsgze 6vpSsOVSgpo+YV7a/flHyDnSHkw8Q0CbPM/I05LGFD5EYcoEYD/QRhlrK20ylGj2yc +7AiHa20RfpPw== Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Update VFIO to take advantage of the recently loosened restriction on FOLL_LONGTERM with get_user_pages_remote(). Also, now it is possible to fix a bug: the VFIO caller is logically a FOLL_LONGTERM user, but it wasn't setting FOLL_LONGTERM. Also, remove an unnessary pair of calls that were releasing and reacquiring the mmap_sem. There is no need to avoid holding mmap_sem just in order to call page_to_pfn(). Also, now that the the DAX check ("if a VMA is DAX, don't allow long term pinning") is in the internals of get_user_pages_remote() and __gup_longterm_locked(), there's no need for it at the VFIO call site. So remove it. Tested-by: Alex Williamson Acked-by: Alex Williamson Reviewed-by: Jason Gunthorpe Reviewed-by: Ira Weiny Suggested-by: Jason Gunthorpe Cc: Dan Williams Cc: Jerome Glisse Signed-off-by: John Hubbard --- drivers/vfio/vfio_iommu_type1.c | 30 +++++------------------------- 1 file changed, 5 insertions(+), 25 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 2ada8e6cdb88..b800fc9a0251 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -322,7 +322,6 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, { struct page *page[1]; struct vm_area_struct *vma; - struct vm_area_struct *vmas[1]; unsigned int flags = 0; int ret; @@ -330,33 +329,14 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, flags |= FOLL_WRITE; down_read(&mm->mmap_sem); - if (mm == current->mm) { - ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page, - vmas); - } else { - ret = get_user_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 - * lead to indefinite stalls in filesystem operations. - * Disallow attempts to pin fs-dax pages via this - * interface. - */ - if (ret > 0 && vma_is_fsdax(vmas[0])) { - ret = -EOPNOTSUPP; - put_page(page[0]); - } - } - up_read(&mm->mmap_sem); - + ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM, + page, NULL, NULL); if (ret == 1) { *pfn = page_to_pfn(page[0]); - return 0; + ret = 0; + goto done; } - down_read(&mm->mmap_sem); - vaddr = untagged_addr(vaddr); vma = find_vma_intersection(mm, vaddr, vaddr + 1); @@ -366,7 +346,7 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, if (is_invalid_reserved_pfn(*pfn)) ret = 0; } - +done: up_read(&mm->mmap_sem); return ret; }