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 97DCDC5519F for ; Wed, 25 Nov 2020 08:28:01 +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 3C199206CA for ; Wed, 25 Nov 2020 08:28:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=virtuozzo.com header.i=@virtuozzo.com header.b="kPQ1TyWB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3C199206CA 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]:34126 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1khq9f-0003QJ-0T for qemu-devel@archiver.kernel.org; Wed, 25 Nov 2020 03:27:59 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:37922) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1khq8M-0002R3-P8 for qemu-devel@nongnu.org; Wed, 25 Nov 2020 03:26:38 -0500 Received: from mail-eopbgr80134.outbound.protection.outlook.com ([40.107.8.134]:36485 helo=EUR04-VI1-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 1khq8I-00074m-LD for qemu-devel@nongnu.org; Wed, 25 Nov 2020 03:26:37 -0500 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=NcLu6IzXg+zN7Stmrc4+/t58I8k/eQSW2iBn9QuSS5j6DtODxFER3jDsy+kB/LrBF1rFcrPilGxad/xt4q3XOtrbcGHZpuCo4obStVUZ1rb4i0R7hu9NrTfkdSpscVerkz7Yy+aYg0+jarxjCxgCoKqiORb48qyHbfxictmVtWqWkEpQv1ZgiLTqwxfF6/wTztdxIbs6eJXixq55qceErAkRtA6Dq+fnpfgFXir/0C5VkBAraW0fO7j3BGS9OTFHnzytAfCyhn4hGlcc/SNfVAWf/9VnWKFcFxTCvxqpiB13irXVx34YJV5LoHzYG9qbOzhfPydlI3V2412v+pL36g== 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=yvvYT2/UOfoOunTZzUuDy6uRJlkNgqOvSsR2gmqpUZY=; b=d7Wukoq0YmSHtJ6z1PLDp5jadFcM+ysQBQdhsaVYDERM1hlKiaPzeqtutfGKx0Ss4Hz4+1oy8Phfr00yLeTBTdC1k0/vbz8qH4hSd2EdjLu2Nw5nhqLWHrtIHvDF9Y6k5jV3oG1aEuZiYkV6ikFGObWAX0OqIHWrqd583GvvtWqOZJXy0PvY9+TaGy/ILXs/uxp/k6h30Iv1ysl4/0hiouu88p9sIWGVeNpPzdg23v+nTEHJKGI4vRzdH/Gs30Gr77mzgacCnBitvqjDxwJSYX7G18ukvPi0LgOkPyeHHQSXrKoFoR3dzaTP2VdLdlHrJOtjiEjkPaxkRZZadZFPJQ== 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=yvvYT2/UOfoOunTZzUuDy6uRJlkNgqOvSsR2gmqpUZY=; b=kPQ1TyWBBZv4uL7QzfsFu9f6p5nPwyKqPPCGlOFtGpqaDRTKhK2JEDDJi53+fI/iPVjd/hGIm0hYRpuUf4aoJQAdiZFoRItIActXs7/TCj8EVRefrnjgd2ot1MPEVUkWCrfOSz3vGZ9CmTi4L2wlqJL1LrR0Qb1c/alxErwXOQU= 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 VI1PR0801MB1789.eurprd08.prod.outlook.com (2603:10a6:800:52::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3589.25; Wed, 25 Nov 2020 08:11:26 +0000 Received: from VI1PR0802MB2510.eurprd08.prod.outlook.com ([fe80::8d6a:734c:e4a2:8543]) by VI1PR0802MB2510.eurprd08.prod.outlook.com ([fe80::8d6a:734c:e4a2:8543%7]) with mapi id 15.20.3589.030; Wed, 25 Nov 2020 08:11:26 +0000 Subject: Re: [PATCH v3 2/7] 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: <20201119125940.20017-1-andrey.gruzdev@virtuozzo.com> <20201119125940.20017-3-andrey.gruzdev@virtuozzo.com> <20201124175712.GM3366@work-vm> From: Andrey Gruzdev Message-ID: <24483c0d-107f-427e-87b1-f4e039bfe486@virtuozzo.com> Date: Wed, 25 Nov 2020 11:11:23 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 In-Reply-To: <20201124175712.GM3366@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: AM3PR07CA0075.eurprd07.prod.outlook.com (2603:10a6:207:4::33) 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 AM3PR07CA0075.eurprd07.prod.outlook.com (2603:10a6:207:4::33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3611.16 via Frontend Transport; Wed, 25 Nov 2020 08:11:25 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 160f839f-5788-426b-c86f-08d89119b445 X-MS-TrafficTypeDiagnostic: VI1PR0801MB1789: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:751; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: TKqfs19G+PymVdhsm1slM5tJFIDyS1SMngOXjare0xJ7OZ7q0eK1C3tfF+JhhNmwdYJx7KF8BcCtlZFylZyU+9cbvIo8x/Zxcji7XQ0fZh6rTLFSpQmQ0shNz/hFFLMxnF/5RUaxzxSe9LeGHZW+ULW4IJGiVDXlvp9PgNcN7fOTvDT1jjFlIv1/wbyvU5S9iqNK8Sp/nsPG83mxHgCyN0r4uR+HVH9Eym4zw3CRpJPa1lJCZW5ryNB2xVK2/cw3o85ChHLeAOgrmHpX2qqXy9H6urur2C6NbfCxVE/6cXJv34/6nwiOCH+C3/xlaBqE3gVtiGuoc0PVpNEZaqn7JBeAfiN+oRjICt4NrZkt20A8ha2L4V5wTjUMjuBUqUTa 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)(396003)(346002)(39830400003)(366004)(86362001)(66476007)(66556008)(316002)(2906002)(4326008)(36756003)(16576012)(26005)(66946007)(186003)(30864003)(31696002)(16526019)(2616005)(5660300002)(956004)(44832011)(54906003)(6486002)(478600001)(8936002)(53546011)(8676002)(83380400001)(52116002)(6916009)(31686004)(43740500002); DIR:OUT; SFP:1102; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?Y2wvOXlLeXZXWnZMTURNZGMvL0swTXVRL1A3eG1KVThJd2U4dFBHcEVjK21L?= =?utf-8?B?bEFYYzgyWTkwYnNaV0dWZm50enFQb2FNbW5ZdzV6QllpcnFaZ1g4ZG5oNGtG?= =?utf-8?B?Smx2UytiRmhvclpGTjB5S1NrQS9yWEdrbFZGOStuaGk2NjBQZVpEanFxNE5z?= =?utf-8?B?dXJLVkhvYUN1eVNjZ05tVTAydEtYWFNQc1Z5STl1R09nZUc4VmJoUFVJNVRJ?= =?utf-8?B?YXdraGZiNS9sYnVFSTVrR3JLVExidjd3S0ZieUVOU1dOQ2gvaU03K3hyVkp3?= =?utf-8?B?M0dIcWRqditCeGx0Wjg1ZTZVMVRvNnBPejFKaUwxM2dCRVZhSHZHUWJmTWhH?= =?utf-8?B?dTJrbENBN1pJbmo3VVB3NU16QW5TTXA5cklLZ203UjZMT01ia01ZV2pTV3U1?= =?utf-8?B?SzlDWUFJV1NjRG5sRUxhOHlqcGNuRHcybml3dk9rc1E0eW9jWHIreUZrRnhh?= =?utf-8?B?S1k3MVdoQ1BSa1Z3WHVibkcreGp5aHRuc0JhOURobnM0KzcrZllxOGQ5U2Rr?= =?utf-8?B?MkUweVMraGhjTHA5V1IzbnBQUjdPdm4wUHhRamNFR3VXYjhuY0RFMEdjR0pG?= =?utf-8?B?MkNwQ2VZdENvbkZueVFud1dEWmQ2WnBHUmFHZXpibWc5cmt1WW5TTjQvaEYx?= =?utf-8?B?S2dxSDJCbnFLMWhmcnMzWDV2Y2syUDYwb0ZOQkpLN3c3TmwvSXlaOUFXbitJ?= =?utf-8?B?dmJPTkpadjZ3VGZydTZ3NmN0RWYydW1qVitwRzNTZnZ3NDNSZkJCSXIwdEhZ?= =?utf-8?B?eTBMZmU0aWJoMXRQdUMxSVltNmRYa3ordi9WTENONFoxeTlPQWovbG0wNDh0?= =?utf-8?B?TFFGVC9vRDFQQm1XQm5yYWhwelpLbnZBc3BwaWt6V25ZNnpiY1ZCeU9xaVhF?= =?utf-8?B?dE5Kc3FRRzFYdXY1cmY1bFdLZ0xXK1owazFwckJaZ0JMZUhZTXVqMVB6Zzh6?= =?utf-8?B?RXNJV052OUxIVy9zM2UvclhWWi9iY3BSellEK1RvT0dLTGtaTzZTU1ZDYUl5?= =?utf-8?B?NS9YbUhDeklFRUJIY2xpbFhXWVdsdGZWVlVESm9PNDF4cTMxQUtFLzBleUZW?= =?utf-8?B?amUrWkxWT0NOTDc5ak54M250TEUrdHNXTC9mR1MxbnFJMHhJa3B5NXNZNTB1?= =?utf-8?B?SkpFNDdnUTJ2eUJLYm9kSzBXNzhabjNVTlIwMzl4cnF0WVNINmxMaExpNk9t?= =?utf-8?B?aGRGOVljZ2REL3NzSTJrNDlUZWNnN1AwSkJjL1NXandDVy8wa09yOTNKRmZx?= =?utf-8?B?eDAzcTJEb1EyWnczMXdWYjY3c1pBSDYrd2NnQUZqTGo2bU1QSklDcWlMbFZZ?= =?utf-8?Q?z+aM7LZXESSWE=3D?= X-OriginatorOrg: virtuozzo.com X-MS-Exchange-CrossTenant-Network-Message-Id: 160f839f-5788-426b-c86f-08d89119b445 X-MS-Exchange-CrossTenant-AuthSource: VI1PR0802MB2510.eurprd08.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Nov 2020 08:11:25.8846 (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: otMwo0jSmKXMmXzPS0dY4ztCaIIxEDTtENs2yGduW2gR7zb8QbEcBzTz/pANa6CUQM2nVx17cmhou/srVcQgfNWuOXQNMQC2LcIwtbVYi5E= X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0801MB1789 Received-SPF: pass client-ip=40.107.8.134; envelope-from=andrey.gruzdev@virtuozzo.com; helo=EUR04-VI1-obe.outbound.protection.outlook.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, 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 24.11.2020 20:57, 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 ++ >> migration/ram.c | 267 ++++++++++++++++++++++++++++++++++++++++++ >> migration/ram.h | 4 + >> 3 files changed, 278 insertions(+) >> >> 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/migration/ram.c b/migration/ram.c >> index 7811cde643..7f273c9996 100644 >> --- a/migration/ram.c >> +++ b/migration/ram.c >> @@ -56,6 +56,12 @@ >> #include "savevm.h" >> #include "qemu/iov.h" >> #include "multifd.h" >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include "sysemu/runstate.h" >> >> /***********************************************************/ >> /* ram save/restore */ >> @@ -298,6 +304,8 @@ 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 */ >> @@ -453,6 +461,181 @@ static QemuThread *decompress_threads; >> static QemuMutex decomp_done_lock; >> static QemuCond decomp_done_cond; >> >> +/** >> + * uffd_create_fd: create UFFD file descriptor >> + * >> + * Returns non-negative file descriptor or negative value in case of an error >> + */ >> +static int uffd_create_fd(void) >> +{ >> + int uffd; >> + struct uffdio_api api_struct; >> + uint64_t ioctl_mask = BIT(_UFFDIO_REGISTER) | BIT(_UFFDIO_UNREGISTER); > > You need to be a bit careful about doing this in migration/ram.c - it's > generic code; at minimum it needs ifdef'ing for Linux. > Yes, it's totally linux-specific, I think better to move this code out of migration/ram.c, as Peter proposed. >> + uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); >> + if (uffd < 0) { >> + error_report("uffd_create_fd() failed: UFFD not supported"); >> + 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; > > Should we be putting that somewher that we can share with postcopy? > Sure, maybe to util/uffd-wp.c + include/qemu/uffd-wp.h. What do you think? >> +fail: >> + close(uffd); >> + return -1; >> +} >> + >> +/** >> + * uffd_close_fd: close UFFD file descriptor >> + * >> + * @uffd: UFFD file descriptor >> + */ >> +static 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 >> + */ >> +static 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", >> + start, length, uffd_register.mode, 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 >> + */ >> +static 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; >> +} >> + >> +__attribute__ ((unused)) >> +static int uffd_read_events(int uffd, struct uffd_msg *msgs, int count); >> +__attribute__ ((unused)) >> +static bool uffd_poll_events(int uffd, int tmo); >> + >> +/** >> + * 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 >> + */ >> +static 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 >> + */ >> +static 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; >> +} >> + >> static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block, >> ram_addr_t offset, uint8_t *source_buf); >> >> @@ -3788,6 +3971,90 @@ 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) >> +{ >> + 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; >> + } >> + >> + /* 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; >> + } >> + bs->flags |= RAM_UF_WRITEPROTECT; >> + >> + 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: >> + uffd_close_fd(uffd); >> + rs->uffdio_fd = -1; >> + return -1; >> +} >> + >> +/** >> + * ram_write_tracking_stop: stop UFFD-WP memory tracking and remove protection >> + */ >> +void ram_write_tracking_stop(void) >> +{ >> + RAMState *rs = ram_state; >> + RAMBlock *bs; >> + assert(rs->uffdio_fd >= 0); >> + >> + RAMBLOCK_FOREACH_NOT_IGNORED(bs) { >> + if ((bs->flags & RAM_UF_WRITEPROTECT) == 0) { >> + continue; >> + } >> + 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); >> + /* Cleanup flags */ >> + bs->flags &= ~RAM_UF_WRITEPROTECT; >> + } >> + >> + /* >> + * Close UFFD file descriptor to remove protection, >> + * release registered memory regions and flush wait queues >> + */ >> + uffd_close_fd(rs->uffdio_fd); >> + rs->uffdio_fd = -1; >> +} >> + >> 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..3611cb51de 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); >> >> +/* Live snapshots */ >> +int ram_write_tracking_start(void); >> +void ram_write_tracking_stop(void); >> + >> #endif >> -- >> 2.25.1 >> -- Andrey Gruzdev, Principal Engineer Virtuozzo GmbH +7-903-247-6397 virtuzzo.com