From patchwork Tue Jan 7 22:45:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11322201 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 02C716C1 for ; Tue, 7 Jan 2020 22:48:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0E1A2075A for ; Tue, 7 Jan 2020 22:48:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="kgw5qi7r" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728250AbgAGWsH (ORCPT ); Tue, 7 Jan 2020 17:48:07 -0500 Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:5201 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727629AbgAGWqK (ORCPT ); Tue, 7 Jan 2020 17:46:10 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 07 Jan 2020 14:45:45 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Tue, 07 Jan 2020 14:46:03 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 07 Jan 2020 14:46:03 -0800 Received: from HQMAIL107.nvidia.com (172.20.187.13) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 7 Jan 2020 22:46:00 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Tue, 7 Jan 2020 22:46:00 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Tue, 07 Jan 2020 14:46:00 -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?= , "Kirill A . Shutemov" , "Magnus Karlsson" , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML , John Hubbard , "Jason Gunthorpe" Subject: [PATCH v12 07/22] vfio: fix FOLL_LONGTERM use, simplify get_user_pages_remote() call Date: Tue, 7 Jan 2020 14:45:43 -0800 Message-ID: <20200107224558.2362728-8-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200107224558.2362728-1-jhubbard@nvidia.com> References: <20200107224558.2362728-1-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=1578437145; 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=kgw5qi7rLOID9QQ3ZZ+89yHfH+EZf9iCt5v7sqjnSkNGTKImtJ6iZV1n1JD4hoQrz dHwTPXAsNVPUPQDnhc3SRhBDod+kQgTmakqImItPRd8R5gr6SmbYIWWEXc5rrzKPnV QdGdycKRT6qOUk3Df6io8ReGDjAbnpM2ZNVj/VOnXRx8fGN+lmoCSjvPKGtNbSaosI 2c0JlXhjlcpRPnMRB3gftea/FvhEgYPKyjiIDayufI1tRbPurKeRiR/aLQT6qfVnAW PcpboBFyIWRB0+U7WaI+V5+PDuc+smR774udQbs69C4cjQ/uuDeozXDJDjGby2P64v q1ciYMF6hOGCg== Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@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; }