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=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 4B609C64E7A for ; Tue, 1 Dec 2020 19:35:44 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F2EC220679 for ; Tue, 1 Dec 2020 19:35:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=virtuozzo.com header.i=@virtuozzo.com header.b="jDrYHhki" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F2EC220679 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=virtuozzo.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47732 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kkBR7-00054g-TH for qemu-devel@archiver.kernel.org; Tue, 01 Dec 2020 14:35:41 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41842) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kkBNy-0002eu-LQ for qemu-devel@nongnu.org; Tue, 01 Dec 2020 14:32:27 -0500 Received: from mail-eopbgr150101.outbound.protection.outlook.com ([40.107.15.101]:4582 helo=EUR01-DB5-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kkBNq-0007Uk-Pf for qemu-devel@nongnu.org; Tue, 01 Dec 2020 14:32:23 -0500 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=eqeCuprT5CB9Qylqw7JoTFKfYsloksjOuLiyjZ9c3nXjd4U1gBdpR7POB7m4gcJJolGLyigeRIs3RB+i4wKP6WKFovA/uINugDiBPbbk0+IfqREOr8gUGJ0jlTJN4vZh61hmYFGYo/95gGATqev1pzYFfC/UDyqPmoRplVpts59jwjC78HA5RcRYI2dnatw2ojkLTU9VOEa39nhgt86wYOakaDm6nK9LmxzGe6d4vcHOP6seyJrkIMJGt6HWzXwdE/Fgfw+88umiHAid3kkd4gBCekP8oAAoLMsyGb0DdYC8CSzILmpVNmBuKVlt2EMgjHyQPZCajkzOPzvDxeRuIg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=tNFXk5VL6/VR+N37P05uqBSp3ueXhWT3ovPWYufiKKk=; b=Nm1Rfi7AjYs+r8bxZKbIKgTimVmZI6rxWTAz6QrdEB3UHQ+ker+4CqvcjCeWcbYdyuub7oJn0D3THzDhl06VXpWV17Cs7nbE9sQgQ2ZKnsI68YkQrsmxI/UhePDbsoVzRr07yT609gG55NaHA/+CM11xW8tpNcvz7+GLFUB4EwTIMStIA9R0e08P2PXTiJAiPPt8SAjj81yMytU17zO6mvYJTc39P1iElWS39NSTnCN/a0T+8a0Bw2533Ezp3oN+tU8VeSzpL0/zyK48A8iQQK8ZP1m+b6/spHrQTEyGCWWKUTeicDl6gIYtrmlwE3c4pEI1h7kOIT9YMZSX0LbPZg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=virtuozzo.com; dmarc=pass action=none header.from=virtuozzo.com; dkim=pass header.d=virtuozzo.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=virtuozzo.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=tNFXk5VL6/VR+N37P05uqBSp3ueXhWT3ovPWYufiKKk=; b=jDrYHhkiNZdu0EiTQR03cbn9GpFSJ6wEm6JKTDZ9ILsM9ogL3Bt2Pqv/NpYUh+e9XXzophTVo+L7lWrx7SrljjtS6/Fv8F+5Bxut3AXIDaZVQ5W4iWKR3FN5ABkr199ZMFfwQCs37+DVWSl/0+hl0gwhdcJ+u1LsYUwgPpU2Mk4= Authentication-Results: redhat.com; dkim=none (message not signed) header.d=none;redhat.com; dmarc=none action=none header.from=virtuozzo.com; Received: from VI1PR0802MB2510.eurprd08.prod.outlook.com (2603:10a6:800:ad::14) by VI1PR08MB3680.eurprd08.prod.outlook.com (2603:10a6:803:79::27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3564.28; Tue, 1 Dec 2020 19:32:15 +0000 Received: from VI1PR0802MB2510.eurprd08.prod.outlook.com ([fe80::ac70:da6f:e05d:1cc9]) by VI1PR0802MB2510.eurprd08.prod.outlook.com ([fe80::ac70:da6f:e05d:1cc9%12]) with mapi id 15.20.3611.025; Tue, 1 Dec 2020 19:32:15 +0000 Subject: Re: [PATCH v4 2/6] introduce UFFD-WP low-level interface helpers To: "Dr. David Alan Gilbert" Cc: qemu-devel@nongnu.org, Den Lunev , Eric Blake , Paolo Bonzini , Juan Quintela , Markus Armbruster , Peter Xu References: <20201126151734.743849-1-andrey.gruzdev@virtuozzo.com> <20201126151734.743849-3-andrey.gruzdev@virtuozzo.com> <20201201122417.GF4338@work-vm> From: Andrey Gruzdev Message-ID: <6d636bd9-6497-a0ca-ce1a-9498600e6ca8@virtuozzo.com> Date: Tue, 1 Dec 2020 22:32:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 In-Reply-To: <20201201122417.GF4338@work-vm> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [95.165.26.68] X-ClientProxiedBy: AM4PR0302CA0034.eurprd03.prod.outlook.com (2603:10a6:205:2::47) To VI1PR0802MB2510.eurprd08.prod.outlook.com (2603:10a6:800:ad::14) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.1.64] (95.165.26.68) by AM4PR0302CA0034.eurprd03.prod.outlook.com (2603:10a6:205:2::47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3611.23 via Frontend Transport; Tue, 1 Dec 2020 19:32:14 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: f6bbc625-de89-41a5-ee17-08d8962fce93 X-MS-TrafficTypeDiagnostic: VI1PR08MB3680: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:849; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: qVTs8tbvrQ1L5DPzTRLTazoxokcme7YnsnsQTYvCXEk4M2d9Q1iM9AhKvL1e4MOzJkGbp+ios9IYxCWs9+h2SJ4OUggMVsF+yKDRc8gCD3gjLm9rUB+nV/VPjxjj2pc4JeGmZo4bASJMsKD7pMWj4zMSA89wLaanCKgl9CmR+CVR2m9ZOlI0Zb58rs1LeLdX9NCy51S6F5gQs4DsIqnFxCZhfia/nVgXCh5BmYVMhjVbWB5tug4cj9G1njpLVWGw3MHUaht/S1sSE35ap5n/FkyRwod+8FTdfChS6KxXmiBzBgs+F22SQL3oROR1LKCYEJznITJ4lo/kiC9b3fcKlHaSw50ggfBWOUywZgICtkyGBvtrdmBlj5LRjAuZRgtH X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:VI1PR0802MB2510.eurprd08.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(136003)(376002)(39850400004)(346002)(366004)(396003)(5660300002)(83380400001)(4326008)(31686004)(6916009)(36756003)(16576012)(8936002)(6486002)(316002)(54906003)(86362001)(16526019)(26005)(2616005)(186003)(44832011)(956004)(478600001)(52116002)(31696002)(8676002)(53546011)(66946007)(66556008)(66476007)(2906002)(30864003)(43740500002); DIR:OUT; SFP:1102; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?UkZ2RTJsZmxYNTJXcjJYWFB1V0lyem9vL3JsbGhpSGpkeWg4RGN6d1dqWFRi?= =?utf-8?B?bmNRc3VFNWtOQnJuNmVyOGVvaEl4MjNhYXNsajd4bTBXY2dEQUtwd2Fib0Jx?= =?utf-8?B?bE0yelZLQVVhL01OQTZ1cVdMUzNYMnVVVDZUeUQybVBjcHdwdFBXcHNRZnBw?= =?utf-8?B?b0ZJYTdjb3I5R3NiRTlRZi9QMTdyb3dWclB4Y2F5TllHUFh5L1lER21OVTJx?= =?utf-8?B?aEZmWVk2K3NDU2t2Uy9KOWlMWXhPakt2YW1oVlF5eWM5YnB0TStSbEVLWlhh?= =?utf-8?B?WEJxVjVPZFRPZ2piZ2VSNFcwUEMxOC8xMFFoclpWSWtqR29td3diVHZ5Ty83?= =?utf-8?B?R1R4SEQ2LzlFWURZLzJ4VjFUVUFDallvSXZQMDkwdW5teVdWNVdyTlpTVXU0?= =?utf-8?B?THNRNVR4cjRMWUx3RnhUY1ZzQVRONURCWTRjeG4rZDVBTy9zN0FGN3ZRaGQx?= =?utf-8?B?UGFBTXU3VlhuOEtzR1p4U0FlQlU4TUQ4RDZkY1FzUzNzUEZrUHRQL1FrbFFQ?= =?utf-8?B?Q00vNFh2RmFZOVhvbmpoSHdFSmpINnZUS0FSZkQ2NWFhUldlcGxVOXRoSXRR?= =?utf-8?B?MmlnUHhlRm92bVh2c0gxaHI4dVJ6ZXo5KytsWjQ0VS92Z2VDaVkvSXVYbjl4?= =?utf-8?B?UDkzOEFWKzNYSzBRNWNEVlpMa1pSN0xKaWxkSlRMTHF1QmV1MG5Sd21Pc0lX?= =?utf-8?B?MjBHTS9CaWhhbUpSRlVRVTd4VTh4dllMdDhHTTlxRXJ5c0pMUUhjZDBrWGMz?= =?utf-8?B?SXZJOXRZNzQ4R0hsTCtQVjZvY1NaYm8xb3d5VzN4cko5TExLWXVPbWYzN2pM?= =?utf-8?B?L0p3QXRnQTE1WE5LcDlVbUhhWE5ZOXVmVlJLMVdkR3dnSlJwUG9XdnV5ZEJN?= =?utf-8?B?REJvUi9NeXppbzlCQ3RBaS9aZjlJWWZsN0RqRDBFZmJ0NDJGdGViWnMrL3NU?= =?utf-8?B?VXpTN1cxMEpwTHRyNGRKdEJOUzltSWFKTVhVVVR4K0tZMWc5ZXAxNzBxenRE?= =?utf-8?B?a0J6N0pIOTMxektrVWFGTkRhNVpHUlBIMjZaZWRIM2hlWWRNK1FaMzdacUI5?= =?utf-8?B?VTljVUZmS084ME4wOEszVkRyalNIOUFScXpxMTg2Y2Jia3A4V1R3QnRqdzQ4?= =?utf-8?B?Q3RGbG1QN0V2aGIyb05FVXVLOUFCcVpuQ3Z1MnMzRFllN01hbkswZ1dwa3dt?= =?utf-8?B?bTRtaWovdFVEVGZ1SGMzL1V2WGRyaGZnelFUUmgrT0E0K04yamtPUGUrTi9E?= =?utf-8?B?QUtjZGdTT3BocUJRcER4YU5vV2kySTlaTjF2eFFBR0tMOUdRQUJuaWRuVGpF?= =?utf-8?Q?ezqGwKXxqWcbk=3D?= X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-Network-Message-Id: f6bbc625-de89-41a5-ee17-08d8962fce93 X-MS-Exchange-CrossTenant-AuthSource: VI1PR0802MB2510.eurprd08.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Dec 2020 19:32:14.9544 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 0bc7f26d-0264-416e-a6fc-8352af79c58f X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 0qdrhWjN9osgZOsWtOQKmgPWha2Y0ZVn8SnYUWw1iDN9cy2XyJLDG9j6LFZ/rkUeW5JZ6cujsEYt8fTscej0AwQFVhiIwuBebZJxzNiZhBc= X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR08MB3680 Received-SPF: pass client-ip=40.107.15.101; envelope-from=andrey.gruzdev@virtuozzo.com; helo=EUR01-DB5-obe.outbound.protection.outlook.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MSGID_FROM_MTA_HEADER=0.001, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 01.12.2020 15:24, Dr. David Alan Gilbert wrote: > * Andrey Gruzdev (andrey.gruzdev@virtuozzo.com) wrote: >> Implemented support for the whole RAM block memory >> protection/un-protection. Introduced higher level >> ram_write_tracking_start() and ram_write_tracking_stop() >> to start/stop tracking guest memory writes. >> >> Signed-off-by: Andrey Gruzdev >> --- >> include/exec/memory.h | 7 ++ >> include/qemu/userfaultfd.h | 29 +++++ >> migration/ram.c | 120 +++++++++++++++++++++ >> migration/ram.h | 4 + >> util/meson.build | 1 + >> util/userfaultfd.c | 215 +++++++++++++++++++++++++++++++++++++ >> 6 files changed, 376 insertions(+) >> create mode 100644 include/qemu/userfaultfd.h >> create mode 100644 util/userfaultfd.c >> >> diff --git a/include/exec/memory.h b/include/exec/memory.h >> index 0f3e6bcd5e..3d798fce16 100644 >> --- a/include/exec/memory.h >> +++ b/include/exec/memory.h >> @@ -139,6 +139,13 @@ typedef struct IOMMUNotifier IOMMUNotifier; >> /* RAM is a persistent kind memory */ >> #define RAM_PMEM (1 << 5) >> >> +/* >> + * UFFDIO_WRITEPROTECT is used on this RAMBlock to >> + * support 'write-tracking' migration type. >> + * Implies ram_state->ram_wt_enabled. >> + */ >> +#define RAM_UF_WRITEPROTECT (1 << 6) >> + >> static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn, >> IOMMUNotifierFlag flags, >> hwaddr start, hwaddr end, >> diff --git a/include/qemu/userfaultfd.h b/include/qemu/userfaultfd.h >> new file mode 100644 >> index 0000000000..fb843c76db >> --- /dev/null >> +++ b/include/qemu/userfaultfd.h >> @@ -0,0 +1,29 @@ >> +/* >> + * Linux UFFD-WP support >> + * >> + * Copyright Virtuozzo GmbH, 2020 >> + * >> + * Authors: >> + * Andrey Gruzdev >> + * >> + * This work is licensed under the terms of the GNU GPL, version 2 or >> + * later. See the COPYING file in the top-level directory. >> + */ >> + >> +#ifndef USERFAULTFD_H >> +#define USERFAULTFD_H >> + >> +#include "qemu/osdep.h" >> +#include "exec/hwaddr.h" >> +#include >> + >> +int uffd_create_fd(void); >> +void uffd_close_fd(int uffd); >> +int uffd_register_memory(int uffd, hwaddr start, hwaddr length, >> + bool track_missing, bool track_wp); >> +int uffd_unregister_memory(int uffd, hwaddr start, hwaddr length); >> +int uffd_protect_memory(int uffd, hwaddr start, hwaddr length, bool wp); >> +int uffd_read_events(int uffd, struct uffd_msg *msgs, int count); >> +bool uffd_poll_events(int uffd, int tmo); >> + >> +#endif /* USERFAULTFD_H */ >> diff --git a/migration/ram.c b/migration/ram.c >> index 7811cde643..3adfd1948d 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -56,6 +56,11 @@ >> #include "savevm.h" >> #include "qemu/iov.h" >> #include "multifd.h" >> +#include "sysemu/runstate.h" >> + >> +#ifdef CONFIG_LINUX >> +#include "qemu/userfaultfd.h" >> +#endif >> >> /***********************************************************/ >> /* ram save/restore */ >> @@ -298,6 +303,8 @@ struct RAMSrcPageRequest { >> struct RAMState { >> /* QEMUFile used for this migration */ >> QEMUFile *f; >> + /* UFFD file descriptor, used in 'write-tracking' migration */ >> + int uffdio_fd; >> /* Last block that we have visited searching for dirty pages */ >> RAMBlock *last_seen_block; >> /* Last block from where we have sent data */ >> @@ -3788,6 +3795,119 @@ static int ram_resume_prepare(MigrationState *s, void *opaque) >> return 0; >> } >> >> +/* >> + * ram_write_tracking_start: start UFFD-WP memory tracking >> + * >> + * Returns 0 for success or negative value in case of error >> + * >> + */ >> +int ram_write_tracking_start(void) > > Please split this stuff off into a separate patch; just make this one > the userfaultfd.[ch] and then a separate one for gluing it into ram.c > Yep, I'm separating it now - userfaultdf.c and ram_write_tracking stuff, they go to different patches. >> +{ >> +#ifdef CONFIG_LINUX >> + int uffd; >> + RAMState *rs = ram_state; >> + RAMBlock *bs; >> + >> + /* Open UFFD file descriptor */ >> + uffd = uffd_create_fd(); >> + if (uffd < 0) { >> + return uffd; >> + } >> + rs->uffdio_fd = uffd; >> + >> + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { >> + /* Nothing to do with read-only and MMIO-writable regions */ >> + if (bs->mr->readonly || bs->mr->rom_device) { >> + continue; >> + } >> + >> + bs->flags |= RAM_UF_WRITEPROTECT; >> + /* Register block memory with UFFD to track writes */ >> + if (uffd_register_memory(rs->uffdio_fd, (hwaddr) bs->host, >> + bs->max_length, false, true)) { >> + goto fail; >> + } >> + /* Apply UFFD write protection to the block memory range */ >> + if (uffd_protect_memory(rs->uffdio_fd, (hwaddr) bs->host, >> + bs->max_length, true)) { >> + goto fail; >> + } >> + >> + info_report("UFFD-WP write-tracking enabled: " >> + "block_id=%s page_size=%zu start=%p length=%lu " >> + "romd_mode=%i ram=%i readonly=%i nonvolatile=%i rom_device=%i", >> + bs->idstr, bs->page_size, bs->host, bs->max_length, >> + bs->mr->romd_mode, bs->mr->ram, bs->mr->readonly, >> + bs->mr->nonvolatile, bs->mr->rom_device); >> + } >> + >> + return 0; >> + >> +fail: >> + error_report("ram_write_tracking_start() failed: restoring initial memory state"); >> + >> + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { >> + if ((bs->flags & RAM_UF_WRITEPROTECT) == 0) { >> + continue; >> + } >> + /* >> + * In case some memory block failed to be write-protected >> + * remove protection and unregister all succeeded RAM blocks >> + */ >> + uffd_protect_memory(rs->uffdio_fd, (hwaddr) bs->host, bs->max_length, false); >> + uffd_unregister_memory(rs->uffdio_fd, (hwaddr) bs->host, bs->max_length); >> + /* Cleanup flags */ >> + bs->flags &= ~RAM_UF_WRITEPROTECT; >> + } >> + >> + uffd_close_fd(uffd); >> + rs->uffdio_fd = -1; >> + return -1; >> +#else >> + rs->uffdio_fd = -1; >> + error_setg(&migrate_get_current()->error, >> + "Background-snapshot not supported on non-Linux hosts"); >> + return -1; >> +#endif /* CONFIG_LINUX */ >> +} >> + >> +/** >> + * ram_write_tracking_stop: stop UFFD-WP memory tracking and remove protection >> + */ >> +void ram_write_tracking_stop(void) >> +{ >> +#ifdef CONFIG_LINUX >> + RAMState *rs = ram_state; >> + RAMBlock *bs; >> + assert(rs->uffdio_fd >= 0); >> + >> + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { >> + if ((bs->flags & RAM_UF_WRITEPROTECT) == 0) { >> + continue; >> + } >> + /* Remove protection and unregister all affected RAM blocks */ >> + uffd_protect_memory(rs->uffdio_fd, (hwaddr) bs->host, bs->max_length, false); >> + uffd_unregister_memory(rs->uffdio_fd, (hwaddr) bs->host, bs->max_length); >> + /* Cleanup flags */ >> + bs->flags &= ~RAM_UF_WRITEPROTECT; >> + >> + info_report("UFFD-WP write-tracking disabled: " >> + "block_id=%s page_size=%zu start=%p length=%lu " >> + "romd_mode=%i ram=%i readonly=%i nonvolatile=%i rom_device=%i", >> + bs->idstr, bs->page_size, bs->host, bs->max_length, >> + bs->mr->romd_mode, bs->mr->ram, bs->mr->readonly, >> + bs->mr->nonvolatile, bs->mr->rom_device); >> + } >> + >> + /* Finally close UFFD file descriptor */ >> + uffd_close_fd(rs->uffdio_fd); >> + rs->uffdio_fd = -1; >> +#else >> + error_setg(&migrate_get_current()->error, >> + "Background-snapshot not supported on non-Linux hosts"); >> +#endif /* CONFIG_LINUX */ >> +} >> + >> static SaveVMHandlers savevm_ram_handlers = { >> .save_setup = ram_save_setup, >> .save_live_iterate = ram_save_iterate, >> diff --git a/migration/ram.h b/migration/ram.h >> index 011e85414e..0ec63e27ee 100644 >> --- a/migration/ram.h >> +++ b/migration/ram.h >> @@ -79,4 +79,8 @@ void colo_flush_ram_cache(void); >> void colo_release_ram_cache(void); >> void colo_incoming_start_dirty_log(void); >> >> +/* Background snapshots */ >> +int ram_write_tracking_start(void); >> +void ram_write_tracking_stop(void); >> + >> #endif >> diff --git a/util/meson.build b/util/meson.build >> index f359af0d46..c64bfe94b3 100644 >> --- a/util/meson.build >> +++ b/util/meson.build >> @@ -50,6 +50,7 @@ endif >> >> if have_system >> util_ss.add(when: 'CONFIG_GIO', if_true: [files('dbus.c'), gio]) >> + util_ss.add(when: 'CONFIG_LINUX', if_true: files('userfaultfd.c')) >> endif >> >> if have_block >> diff --git a/util/userfaultfd.c b/util/userfaultfd.c >> new file mode 100644 >> index 0000000000..038953d7ed >> --- /dev/null >> +++ b/util/userfaultfd.c >> @@ -0,0 +1,215 @@ >> +/* >> + * Linux UFFD-WP support >> + * >> + * Copyright Virtuozzo GmbH, 2020 >> + * >> + * Authors: >> + * Andrey Gruzdev >> + * >> + * This work is licensed under the terms of the GNU GPL, version 2 or >> + * later. See the COPYING file in the top-level directory. >> + */ >> + >> +#include "qemu/osdep.h" >> +#include "qemu/bitops.h" >> +#include "qemu/error-report.h" >> +#include "qemu/userfaultfd.h" >> +#include >> +#include >> +#include >> + >> +/** >> + * uffd_create_fd: create UFFD file descriptor >> + * >> + * Returns non-negative file descriptor or negative value in case of an error >> + */ >> +int uffd_create_fd(void) >> +{ >> + int uffd; >> + struct uffdio_api api_struct; >> + uint64_t ioctl_mask = BIT(_UFFDIO_REGISTER) | BIT(_UFFDIO_UNREGISTER); >> + >> + uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); >> + if (uffd < 0) { >> + error_report("uffd_create_fd() failed: UFFD not supported"); > > Please include the errno (or strerror(errno)) > Ok. >> + return -1; >> + } >> + >> + api_struct.api = UFFD_API; >> + api_struct.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP; >> + if (ioctl(uffd, UFFDIO_API, &api_struct)) { >> + error_report("uffd_create_fd() failed: " >> + "API version not supported version=%llx errno=%i", >> + api_struct.api, errno); >> + goto fail; >> + } >> + >> + if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) { >> + error_report("uffd_create_fd() failed: " >> + "PAGEFAULT_FLAG_WP feature missing"); >> + goto fail; >> + } >> + >> + return uffd; >> + >> +fail: >> + close(uffd); >> + return -1; >> +} > > It would be great if we could find a way to share this with > migration/postcopy-ram.c - this duplicates a lor of > request_ufd_features. > Now I'm changing userfaultfd.c glue code to support also the postcopy requirenments - adding functionality to query UFFD feature support, glue for COPY_PAGE/ZERO_PAGE IOCTLs etc. >> + >> +/** >> + * uffd_close_fd: close UFFD file descriptor >> + * >> + * @uffd: UFFD file descriptor >> + */ >> +void uffd_close_fd(int uffd) >> +{ >> + assert(uffd >= 0); >> + close(uffd); >> +} >> + >> +/** >> + * uffd_register_memory: register memory range with UFFD >> + * >> + * Returns 0 in case of success, negative value on error >> + * >> + * @uffd: UFFD file descriptor >> + * @start: starting virtual address of memory range >> + * @length: length of memory range >> + * @track_missing: generate events on missing-page faults >> + * @track_wp: generate events on write-protected-page faults >> + */ >> +int uffd_register_memory(int uffd, hwaddr start, hwaddr length, >> + bool track_missing, bool track_wp) >> +{ >> + struct uffdio_register uffd_register; >> + >> + uffd_register.range.start = start; >> + uffd_register.range.len = length; >> + uffd_register.mode = (track_missing ? UFFDIO_REGISTER_MODE_MISSING : 0) | >> + (track_wp ? UFFDIO_REGISTER_MODE_WP : 0); >> + >> + if (ioctl(uffd, UFFDIO_REGISTER, &uffd_register)) { >> + error_report("uffd_register_memory() failed: " >> + "start=%0"PRIx64" len=%"PRIu64" mode=%llu errno=%i", > > PRIx64 for mode as well. > Ok. >> + start, length, uffd_register.mode, errno); >> + return -1; >> + } >> + >> + return 0; >> +} >> + >> +/** >> + * uffd_unregister_memory: un-register memory range with UFFD >> + * >> + * Returns 0 in case of success, negative value on error >> + * >> + * @uffd: UFFD file descriptor >> + * @start: starting virtual address of memory range >> + * @length: length of memory range >> + */ >> +int uffd_unregister_memory(int uffd, hwaddr start, hwaddr length) >> +{ >> + struct uffdio_range uffd_range; >> + >> + uffd_range.start = start; >> + uffd_range.len = length; >> + >> + if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_range)) { >> + error_report("uffd_unregister_memory() failed: " >> + "start=%0"PRIx64" len=%"PRIu64" errno=%i", >> + start, length, errno); >> + return -1; >> + } >> + >> + return 0; >> +} >> + >> +/** >> + * uffd_protect_memory: protect/unprotect memory range for writes with UFFD >> + * >> + * Returns 0 on success or negative value in case of error >> + * >> + * @uffd: UFFD file descriptor >> + * @start: starting virtual address of memory range >> + * @length: length of memory range >> + * @wp: write-protect/unprotect >> + */ >> +int uffd_protect_memory(int uffd, hwaddr start, hwaddr length, bool wp) >> +{ >> + struct uffdio_writeprotect uffd_writeprotect; >> + int res; >> + >> + uffd_writeprotect.range.start = start; >> + uffd_writeprotect.range.len = length; >> + uffd_writeprotect.mode = (wp ? UFFDIO_WRITEPROTECT_MODE_WP : 0); >> + >> + do { >> + res = ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect); >> + } while (res < 0 && errno == EINTR); >> + if (res < 0) { >> + error_report("uffd_protect_memory() failed: " >> + "start=%0"PRIx64" len=%"PRIu64" mode=%llu errno=%i", >> + start, length, uffd_writeprotect.mode, errno); >> + return -1; >> + } >> + >> + return 0; >> +} >> + >> +/** >> + * uffd_read_events: read pending UFFD events >> + * >> + * Returns number of fetched messages, 0 if non is available or >> + * negative value in case of an error >> + * >> + * @uffd: UFFD file descriptor >> + * @msgs: pointer to message buffer >> + * @count: number of messages that can fit in the buffer >> + */ >> +int uffd_read_events(int uffd, struct uffd_msg *msgs, int count) >> +{ >> + ssize_t res; >> + do { >> + res = read(uffd, msgs, count * sizeof(struct uffd_msg)); >> + } while (res < 0 && errno == EINTR); >> + >> + if ((res < 0 && errno == EAGAIN)) { >> + return 0; >> + } >> + if (res < 0) { >> + error_report("uffd_read_events() failed: errno=%i", errno); >> + return -1; >> + } >> + >> + return (int) (res / sizeof(struct uffd_msg)); >> +} >> + >> +/** >> + * uffd_poll_events: poll UFFD file descriptor for read >> + * >> + * Returns true if events are available for read, false otherwise >> + * >> + * @uffd: UFFD file descriptor >> + * @tmo: timeout in milliseconds, 0 for non-blocking operation, >> + * negative value for infinite wait >> + */ >> +bool uffd_poll_events(int uffd, int tmo) >> +{ >> + int res; >> + struct pollfd poll_fd = { .fd = uffd, .events = POLLIN, .revents = 0 }; >> + >> + do { >> + res = poll(&poll_fd, 1, tmo); >> + } while (res < 0 && errno == EINTR); >> + >> + if (res == 0) { >> + return false; >> + } >> + if (res < 0) { >> + error_report("uffd_poll_events() failed: errno=%i", errno); >> + return false; >> + } >> + >> + return (poll_fd.revents & POLLIN) != 0; >> +} >> -- >> 2.25.1 >> -- Andrey Gruzdev, Principal Engineer Virtuozzo GmbH +7-903-247-6397 virtuzzo.com