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=-15.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 7AFDAC64E7A for ; Tue, 1 Dec 2020 12:26:00 +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 9AA8420679 for ; Tue, 1 Dec 2020 12:25:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LunY8uHf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9AA8420679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34514 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kk4jG-0000zo-9u for qemu-devel@archiver.kernel.org; Tue, 01 Dec 2020 07:25:58 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:42224) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kk4hy-0000Te-Ez for qemu-devel@nongnu.org; Tue, 01 Dec 2020 07:24:38 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:20570) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kk4hr-00006b-TA for qemu-devel@nongnu.org; Tue, 01 Dec 2020 07:24:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606825468; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=r+Ymo5vL//6oViFMBBvsIy6aeF9vmeS8S2FqVoo88dk=; b=LunY8uHfWs2pULmAR5dqKD1/bk+vbZUt6vhh0Q84x3iWRPZjYshlhf5cbSs55qx8SOns+K Ayr9S7z0dqif2WQ5OtFEnBFcUoP0JhwDL+K1NeOSaBhc0mPMe3btuQ8l2aQRz2fu3P/wsV j5zRl4kF6ZiSPR2mSIfVxU5U2o7LXO4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-498-Eny7E_DdO4ue1XboFcHqNQ-1; Tue, 01 Dec 2020 07:24:27 -0500 X-MC-Unique: Eny7E_DdO4ue1XboFcHqNQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4BA1F56C61; Tue, 1 Dec 2020 12:24:25 +0000 (UTC) Received: from work-vm (ovpn-115-1.ams2.redhat.com [10.36.115.1]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3B2DB60BE5; Tue, 1 Dec 2020 12:24:20 +0000 (UTC) Date: Tue, 1 Dec 2020 12:24:17 +0000 From: "Dr. David Alan Gilbert" To: Andrey Gruzdev Subject: Re: [PATCH v4 2/6] introduce UFFD-WP low-level interface helpers Message-ID: <20201201122417.GF4338@work-vm> References: <20201126151734.743849-1-andrey.gruzdev@virtuozzo.com> <20201126151734.743849-3-andrey.gruzdev@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20201126151734.743849-3-andrey.gruzdev@virtuozzo.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.497, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=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: , Cc: Juan Quintela , qemu-devel@nongnu.org, Peter Xu , Markus Armbruster , Paolo Bonzini , Den Lunev Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * 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 > +{ > +#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)) > + 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. > + > +/** > + * 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. > + 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 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK