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=-10.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 550AAC433E0 for ; Tue, 23 Jun 2020 11:47:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F6A620724 for ; Tue, 23 Jun 2020 11:47:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="O0f174T9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732483AbgFWLrP (ORCPT ); Tue, 23 Jun 2020 07:47:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732245AbgFWLrP (ORCPT ); Tue, 23 Jun 2020 07:47:15 -0400 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 271A2C061573 for ; Tue, 23 Jun 2020 04:47:15 -0700 (PDT) Received: by mail-pg1-x543.google.com with SMTP id b5so9747558pgm.8 for ; Tue, 23 Jun 2020 04:47:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=pDMz4GEEd1HrNqab3SFEgh4HTzshHqZlUT8h2DVo/0o=; b=O0f174T9zxECMIrMcBnJlVgKJZ6AF1eadIxgibscZl51LZvB8RJvrqMkRvOifJ1CI8 /NW27eFVBws4khf4Q2qK+/MggUcJwyAOfD1inExGIsaCdqPgaVcQI/lpgDRKhxW6DZ4c vHpAdYOFKt4Tw7nffVPHnQteL/omtnCI9D+PU6xJ/l+qW4gpxQVfVzLKgBp51y/iJeLb BhsNyPZiZimDHSuuF9JYkugBfFBkWTtmpsgF/s45n0Xfpkd5lBZaZNND2x/AZ06mD0dl fYUJBBGM0VrP/I2mSStcI2uddjS2oYMSuuaGhwQ3LJS5m1Stcz2Fnc79koTI+ITuoj4q Wxow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=pDMz4GEEd1HrNqab3SFEgh4HTzshHqZlUT8h2DVo/0o=; b=Wd9/KfgvmXSGwsPf+bjrGaTU+a/gKjqBjfPEUxRrDyGN1OYFRupunHm4M0vmJyr4Ph wfs5CD7mD+il1gprfWRnt3mhyP9QNKVPHdBlPxGBJxsLkBz19pFAzFTiScwdzInTh1Og LJIUcv8SCtVzFSJfaCcm8vRcp3onzlS35Vt7oYKNbZXxoRQgDNYK7thqHlV0x+03Eftx GC3dYKEX6QEZ5MpP888W0J9YCfrqn8of2g43SyYy6ujLE/QKbvK8RavNwoA7osPqHR7p z6MMUqxzNwIgTjVETK3zYqytR2F5hh74y5cscDvIaJqQdDlN8MCh7pGznoi6LPrrqr9H wt+Q== X-Gm-Message-State: AOAM5322sjQZgiyWae9elkMHustrqULbW2niwpS9QS5ig2TI8JBYYXw9 3c2vXqbVHMCddPKhF/+8npU= X-Google-Smtp-Source: ABdhPJyoqH2qE0gyMJuzujXPkfwbJMIuJEyJhbRiulWkylIrNAE8lewKA/I7Fqiq7o7Uu7FIu8YohA== X-Received: by 2002:a63:6643:: with SMTP id a64mr14118116pgc.246.1592912834633; Tue, 23 Jun 2020 04:47:14 -0700 (PDT) Received: from jordon-HP-15-Notebook-PC.domain.name ([122.179.62.127]) by smtp.gmail.com with ESMTPSA id w203sm6828258pfc.128.2020.06.23.04.47.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Jun 2020 04:47:13 -0700 (PDT) From: Souptick Joarder To: jgross@suse.com, boris.ostrovsky@oracle.com, sstabellini@kernel.org Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, Souptick Joarder , John Hubbard Subject: [RFC PATCH v2] xen/privcmd: Convert get_user_pages*() to pin_user_pages*() Date: Tue, 23 Jun 2020 17:25:28 +0530 Message-Id: <1592913328-15486-1-git-send-email-jrdr.linux@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In 2019, we introduced pin_user_pages*() and now we are converting get_user_pages*() to the new API as appropriate. [1] & [2] could be referred for more information. This is case 5 as per document [1]. As discussed, pages need to be marked as dirty before unpinned it. Previously, if lock_pages() end up partially mapping pages, it used to return -ERRNO due to which unlock_pages() have to go through each pages[i] till *nr_pages* to validate them. This can be avoided by passing correct number partially mapped pages & -ERRNO separately while returning from lock_pages() due to error. With this fix unlock_pages() doesn't need to validate pages[i] till *nr_pages* for error scenario. [1] Documentation/core-api/pin_user_pages.rst [2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/ Signed-off-by: Souptick Joarder Cc: John Hubbard Cc: Boris Ostrovsky --- drivers/xen/privcmd.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index a250d11..eea90cd 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -580,25 +580,30 @@ static long privcmd_ioctl_mmap_batch( static int lock_pages( struct privcmd_dm_op_buf kbufs[], unsigned int num, - struct page *pages[], unsigned int nr_pages) + struct page *pages[], unsigned int nr_pages, int *errno) { unsigned int i; + int pinned = 0, rc = 0; for (i = 0; i < num; i++) { unsigned int requested; - int pinned; + rc += pinned; requested = DIV_ROUND_UP( offset_in_page(kbufs[i].uptr) + kbufs[i].size, PAGE_SIZE); - if (requested > nr_pages) - return -ENOSPC; + if (requested > nr_pages) { + *errno = -ENOSPC; + return rc; + } - pinned = get_user_pages_fast( + pinned = pin_user_pages_fast( (unsigned long) kbufs[i].uptr, requested, FOLL_WRITE, pages); - if (pinned < 0) - return pinned; + if (pinned < 0) { + *errno = pinned; + return rc; + } nr_pages -= pinned; pages += pinned; @@ -613,11 +618,7 @@ static void unlock_pages(struct page *pages[], unsigned int nr_pages) if (!pages) return; - - for (i = 0; i < nr_pages; i++) { - if (pages[i]) - put_page(pages[i]); - } + unpin_user_pages_dirty_lock(pages, nr_pages, 1); } static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) @@ -630,6 +631,7 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) struct xen_dm_op_buf *xbufs = NULL; unsigned int i; long rc; + int errno = 0; if (copy_from_user(&kdata, udata, sizeof(kdata))) return -EFAULT; @@ -683,9 +685,12 @@ static long privcmd_ioctl_dm_op(struct file *file, void __user *udata) goto out; } - rc = lock_pages(kbufs, kdata.num, pages, nr_pages); - if (rc) + rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &errno); + if (errno < 0) { + nr_pages = rc; + rc = errno; goto out; + } for (i = 0; i < kdata.num; i++) { set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr); -- 1.9.1