2015-11-05 21:10:55 +03:00
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/*
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* Postcopy migration for RAM
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*
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* Copyright 2013-2015 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Dave Gilbert <dgilbert@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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/*
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* Postcopy is a migration technique where the execution flips from the
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* source to the destination before all the data has been copied.
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*/
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2016-01-26 21:16:54 +03:00
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#include "qemu/osdep.h"
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2017-04-24 21:50:19 +03:00
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#include "exec/target_page.h"
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2017-04-24 21:07:27 +03:00
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#include "migration.h"
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2017-04-20 19:52:18 +03:00
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#include "qemu-file.h"
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2017-04-20 15:48:46 +03:00
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#include "savevm.h"
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2017-04-20 14:12:24 +03:00
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#include "postcopy-ram.h"
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2017-04-17 21:26:27 +03:00
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#include "ram.h"
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2015-11-05 21:10:55 +03:00
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#include "sysemu/sysemu.h"
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2015-11-05 21:11:23 +03:00
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#include "sysemu/balloon.h"
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2015-11-05 21:10:55 +03:00
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#include "qemu/error-report.h"
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#include "trace.h"
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2015-11-05 21:11:02 +03:00
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/* Arbitrary limit on size of each discard command,
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* keeps them around ~200 bytes
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*/
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#define MAX_DISCARDS_PER_COMMAND 12
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struct PostcopyDiscardState {
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const char *ramblock_name;
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uint16_t cur_entry;
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/*
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* Start and length of a discard range (bytes)
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*/
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uint64_t start_list[MAX_DISCARDS_PER_COMMAND];
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uint64_t length_list[MAX_DISCARDS_PER_COMMAND];
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unsigned int nsentwords;
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unsigned int nsentcmds;
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};
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2015-11-05 21:10:55 +03:00
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/* Postcopy needs to detect accesses to pages that haven't yet been copied
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* across, and efficiently map new pages in, the techniques for doing this
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* are target OS specific.
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*/
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#if defined(__linux__)
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2015-11-05 21:11:17 +03:00
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#include <poll.h>
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2015-11-05 21:10:55 +03:00
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#include <sys/ioctl.h>
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#include <sys/syscall.h>
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#include <asm/types.h> /* for __u64 */
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#endif
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2016-02-23 19:09:15 +03:00
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#if defined(__linux__) && defined(__NR_userfaultfd) && defined(CONFIG_EVENTFD)
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#include <sys/eventfd.h>
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2015-11-05 21:10:55 +03:00
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#include <linux/userfaultfd.h>
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2017-10-30 16:16:30 +03:00
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2017-09-19 19:47:58 +03:00
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/**
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* receive_ufd_features: check userfault fd features, to request only supported
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* features in the future.
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*
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* Returns: true on success
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*
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* __NR_userfaultfd - should be checked before
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* @features: out parameter will contain uffdio_api.features provided by kernel
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* in case of success
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*/
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static bool receive_ufd_features(uint64_t *features)
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2015-11-05 21:10:55 +03:00
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{
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2017-09-19 19:47:58 +03:00
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struct uffdio_api api_struct = {0};
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int ufd;
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bool ret = true;
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/* if we are here __NR_userfaultfd should exists */
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ufd = syscall(__NR_userfaultfd, O_CLOEXEC);
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if (ufd == -1) {
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error_report("%s: syscall __NR_userfaultfd failed: %s", __func__,
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strerror(errno));
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return false;
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}
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2015-11-05 21:10:55 +03:00
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2017-09-19 19:47:58 +03:00
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/* ask features */
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2015-11-05 21:10:55 +03:00
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api_struct.api = UFFD_API;
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api_struct.features = 0;
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if (ioctl(ufd, UFFDIO_API, &api_struct)) {
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2017-09-19 19:47:57 +03:00
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error_report("%s: UFFDIO_API failed: %s", __func__,
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2015-11-05 21:10:55 +03:00
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strerror(errno));
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2017-09-19 19:47:58 +03:00
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ret = false;
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goto release_ufd;
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}
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*features = api_struct.features;
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release_ufd:
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close(ufd);
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return ret;
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}
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/**
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* request_ufd_features: this function should be called only once on a newly
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* opened ufd, subsequent calls will lead to error.
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*
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* Returns: true on succes
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*
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* @ufd: fd obtained from userfaultfd syscall
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* @features: bit mask see UFFD_API_FEATURES
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*/
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static bool request_ufd_features(int ufd, uint64_t features)
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{
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struct uffdio_api api_struct = {0};
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uint64_t ioctl_mask;
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api_struct.api = UFFD_API;
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api_struct.features = features;
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if (ioctl(ufd, UFFDIO_API, &api_struct)) {
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error_report("%s failed: UFFDIO_API failed: %s", __func__,
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strerror(errno));
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2015-11-05 21:10:55 +03:00
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return false;
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}
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ioctl_mask = (__u64)1 << _UFFDIO_REGISTER |
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(__u64)1 << _UFFDIO_UNREGISTER;
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if ((api_struct.ioctls & ioctl_mask) != ioctl_mask) {
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error_report("Missing userfault features: %" PRIx64,
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(uint64_t)(~api_struct.ioctls & ioctl_mask));
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return false;
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}
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2017-09-19 19:47:58 +03:00
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return true;
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}
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static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis)
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{
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uint64_t asked_features = 0;
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static uint64_t supported_features;
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/*
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* it's not possible to
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* request UFFD_API twice per one fd
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* userfault fd features is persistent
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*/
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if (!supported_features) {
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if (!receive_ufd_features(&supported_features)) {
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error_report("%s failed", __func__);
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return false;
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}
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}
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/*
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* request features, even if asked_features is 0, due to
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* kernel expects UFFD_API before UFFDIO_REGISTER, per
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* userfault file descriptor
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*/
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if (!request_ufd_features(ufd, asked_features)) {
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error_report("%s failed: features %" PRIu64, __func__,
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asked_features);
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return false;
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}
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2017-02-24 21:28:42 +03:00
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if (getpagesize() != ram_pagesize_summary()) {
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bool have_hp = false;
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/* We've got a huge page */
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#ifdef UFFD_FEATURE_MISSING_HUGETLBFS
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2017-09-19 19:47:58 +03:00
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have_hp = supported_features & UFFD_FEATURE_MISSING_HUGETLBFS;
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2017-02-24 21:28:42 +03:00
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#endif
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if (!have_hp) {
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error_report("Userfault on this host does not support huge pages");
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return false;
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}
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}
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2015-11-05 21:10:55 +03:00
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return true;
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}
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2017-03-07 21:36:37 +03:00
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/* Callback from postcopy_ram_supported_by_host block iterator.
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*/
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2017-05-17 19:58:10 +03:00
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static int test_ramblock_postcopiable(const char *block_name, void *host_addr,
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2017-03-07 21:36:37 +03:00
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ram_addr_t offset, ram_addr_t length, void *opaque)
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{
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2017-05-17 19:58:10 +03:00
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RAMBlock *rb = qemu_ram_block_by_name(block_name);
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size_t pagesize = qemu_ram_pagesize(rb);
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if (qemu_ram_is_shared(rb)) {
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2017-03-07 21:36:37 +03:00
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error_report("Postcopy on shared RAM (%s) is not yet supported",
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block_name);
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return 1;
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}
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2017-05-17 19:58:10 +03:00
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if (length % pagesize) {
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error_report("Postcopy requires RAM blocks to be a page size multiple,"
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" block %s is 0x" RAM_ADDR_FMT " bytes with a "
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"page size of 0x%zx", block_name, length, pagesize);
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return 1;
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}
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2017-03-07 21:36:37 +03:00
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return 0;
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}
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2015-11-05 21:11:22 +03:00
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/*
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* Note: This has the side effect of munlock'ing all of RAM, that's
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* normally fine since if the postcopy succeeds it gets turned back on at the
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* end.
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*/
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2017-09-19 19:47:56 +03:00
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bool postcopy_ram_supported_by_host(MigrationIncomingState *mis)
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2015-11-05 21:10:55 +03:00
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{
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long pagesize = getpagesize();
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int ufd = -1;
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bool ret = false; /* Error unless we change it */
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void *testarea = NULL;
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struct uffdio_register reg_struct;
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struct uffdio_range range_struct;
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uint64_t feature_mask;
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2017-03-21 11:09:14 +03:00
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if (qemu_target_page_size() > pagesize) {
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2015-11-05 21:10:55 +03:00
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error_report("Target page size bigger than host page size");
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goto out;
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}
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ufd = syscall(__NR_userfaultfd, O_CLOEXEC);
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if (ufd == -1) {
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error_report("%s: userfaultfd not available: %s", __func__,
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strerror(errno));
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goto out;
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}
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/* Version and features check */
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2017-09-19 19:47:58 +03:00
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if (!ufd_check_and_apply(ufd, mis)) {
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2015-11-05 21:10:55 +03:00
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goto out;
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}
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2017-03-07 21:36:37 +03:00
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/* We don't support postcopy with shared RAM yet */
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2017-05-17 19:58:10 +03:00
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if (qemu_ram_foreach_block(test_ramblock_postcopiable, NULL)) {
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2017-03-07 21:36:37 +03:00
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goto out;
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}
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2015-11-05 21:11:22 +03:00
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/*
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* userfault and mlock don't go together; we'll put it back later if
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* it was enabled.
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*/
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if (munlockall()) {
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error_report("%s: munlockall: %s", __func__, strerror(errno));
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return -1;
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}
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2015-11-05 21:10:55 +03:00
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/*
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* We need to check that the ops we need are supported on anon memory
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* To do that we need to register a chunk and see the flags that
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* are returned.
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*/
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testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE |
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MAP_ANONYMOUS, -1, 0);
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if (testarea == MAP_FAILED) {
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error_report("%s: Failed to map test area: %s", __func__,
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strerror(errno));
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goto out;
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}
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g_assert(((size_t)testarea & (pagesize-1)) == 0);
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reg_struct.range.start = (uintptr_t)testarea;
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reg_struct.range.len = pagesize;
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reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
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if (ioctl(ufd, UFFDIO_REGISTER, ®_struct)) {
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error_report("%s userfault register: %s", __func__, strerror(errno));
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goto out;
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}
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range_struct.start = (uintptr_t)testarea;
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range_struct.len = pagesize;
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if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) {
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error_report("%s userfault unregister: %s", __func__, strerror(errno));
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goto out;
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}
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feature_mask = (__u64)1 << _UFFDIO_WAKE |
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(__u64)1 << _UFFDIO_COPY |
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(__u64)1 << _UFFDIO_ZEROPAGE;
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if ((reg_struct.ioctls & feature_mask) != feature_mask) {
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error_report("Missing userfault map features: %" PRIx64,
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(uint64_t)(~reg_struct.ioctls & feature_mask));
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goto out;
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}
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/* Success! */
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ret = true;
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out:
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if (testarea) {
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munmap(testarea, pagesize);
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}
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if (ufd != -1) {
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close(ufd);
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}
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return ret;
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}
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|
2015-11-05 21:11:03 +03:00
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/*
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* Setup an area of RAM so that it *can* be used for postcopy later; this
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* must be done right at the start prior to pre-copy.
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* opaque should be the MIS.
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*/
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static int init_range(const char *block_name, void *host_addr,
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ram_addr_t offset, ram_addr_t length, void *opaque)
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{
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trace_postcopy_init_range(block_name, host_addr, offset, length);
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/*
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* We need the whole of RAM to be truly empty for postcopy, so things
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* like ROMs and any data tables built during init must be zero'd
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* - we're going to get the copy from the source anyway.
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* (Precopy will just overwrite this data, so doesn't need the discard)
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*/
|
2017-03-21 13:35:24 +03:00
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if (ram_discard_range(block_name, 0, length)) {
|
2015-11-05 21:11:03 +03:00
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return -1;
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}
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return 0;
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}
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|
|
/*
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* At the end of migration, undo the effects of init_range
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|
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* opaque should be the MIS.
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|
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*/
|
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|
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static int cleanup_range(const char *block_name, void *host_addr,
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|
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ram_addr_t offset, ram_addr_t length, void *opaque)
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|
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{
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|
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MigrationIncomingState *mis = opaque;
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|
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struct uffdio_range range_struct;
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|
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trace_postcopy_cleanup_range(block_name, host_addr, offset, length);
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/*
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* We turned off hugepage for the precopy stage with postcopy enabled
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* we can turn it back on now.
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|
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*/
|
2015-11-19 18:27:48 +03:00
|
|
|
qemu_madvise(host_addr, length, QEMU_MADV_HUGEPAGE);
|
2015-11-05 21:11:03 +03:00
|
|
|
|
|
|
|
/*
|
|
|
|
* We can also turn off userfault now since we should have all the
|
|
|
|
* pages. It can be useful to leave it on to debug postcopy
|
|
|
|
* if you're not sure it's always getting every page.
|
|
|
|
*/
|
|
|
|
range_struct.start = (uintptr_t)host_addr;
|
|
|
|
range_struct.len = length;
|
|
|
|
|
|
|
|
if (ioctl(mis->userfault_fd, UFFDIO_UNREGISTER, &range_struct)) {
|
|
|
|
error_report("%s: userfault unregister %s", __func__, strerror(errno));
|
|
|
|
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Initialise postcopy-ram, setting the RAM to a state where we can go into
|
|
|
|
* postcopy later; must be called prior to any precopy.
|
|
|
|
* called from arch_init's similarly named ram_postcopy_incoming_init
|
|
|
|
*/
|
|
|
|
int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages)
|
|
|
|
{
|
2017-03-21 13:35:24 +03:00
|
|
|
if (qemu_ram_foreach_block(init_range, NULL)) {
|
2015-11-05 21:11:03 +03:00
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* At the end of a migration where postcopy_ram_incoming_init was called.
|
|
|
|
*/
|
|
|
|
int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
|
|
|
|
{
|
2015-11-05 21:11:17 +03:00
|
|
|
trace_postcopy_ram_incoming_cleanup_entry();
|
|
|
|
|
|
|
|
if (mis->have_fault_thread) {
|
|
|
|
if (qemu_ram_foreach_block(cleanup_range, mis)) {
|
|
|
|
return -1;
|
|
|
|
}
|
2018-02-08 13:31:07 +03:00
|
|
|
/* Let the fault thread quit */
|
2018-02-08 13:31:06 +03:00
|
|
|
atomic_set(&mis->fault_thread_quit, 1);
|
2018-02-08 13:31:07 +03:00
|
|
|
postcopy_fault_thread_notify(mis);
|
|
|
|
trace_postcopy_ram_incoming_cleanup_join();
|
|
|
|
qemu_thread_join(&mis->fault_thread);
|
|
|
|
|
2015-11-05 21:11:17 +03:00
|
|
|
trace_postcopy_ram_incoming_cleanup_closeuf();
|
|
|
|
close(mis->userfault_fd);
|
2018-02-08 13:31:06 +03:00
|
|
|
close(mis->userfault_event_fd);
|
2015-11-05 21:11:17 +03:00
|
|
|
mis->have_fault_thread = false;
|
2015-11-05 21:11:03 +03:00
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:23 +03:00
|
|
|
qemu_balloon_inhibit(false);
|
|
|
|
|
2015-11-05 21:11:22 +03:00
|
|
|
if (enable_mlock) {
|
|
|
|
if (os_mlock() < 0) {
|
|
|
|
error_report("mlock: %s", strerror(errno));
|
|
|
|
/*
|
|
|
|
* It doesn't feel right to fail at this point, we have a valid
|
|
|
|
* VM state.
|
|
|
|
*/
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:17 +03:00
|
|
|
postcopy_state_set(POSTCOPY_INCOMING_END);
|
|
|
|
|
2015-11-05 21:11:10 +03:00
|
|
|
if (mis->postcopy_tmp_page) {
|
2017-02-24 21:28:35 +03:00
|
|
|
munmap(mis->postcopy_tmp_page, mis->largest_page_size);
|
2015-11-05 21:11:10 +03:00
|
|
|
mis->postcopy_tmp_page = NULL;
|
|
|
|
}
|
2017-02-24 21:28:36 +03:00
|
|
|
if (mis->postcopy_tmp_zero_page) {
|
|
|
|
munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
|
|
|
|
mis->postcopy_tmp_zero_page = NULL;
|
|
|
|
}
|
2015-11-05 21:11:17 +03:00
|
|
|
trace_postcopy_ram_incoming_cleanup_exit();
|
2015-11-05 21:11:03 +03:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:20 +03:00
|
|
|
/*
|
|
|
|
* Disable huge pages on an area
|
|
|
|
*/
|
|
|
|
static int nhp_range(const char *block_name, void *host_addr,
|
|
|
|
ram_addr_t offset, ram_addr_t length, void *opaque)
|
|
|
|
{
|
|
|
|
trace_postcopy_nhp_range(block_name, host_addr, offset, length);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Before we do discards we need to ensure those discards really
|
|
|
|
* do delete areas of the page, even if THP thinks a hugepage would
|
|
|
|
* be a good idea, so force hugepages off.
|
|
|
|
*/
|
2015-11-19 18:27:48 +03:00
|
|
|
qemu_madvise(host_addr, length, QEMU_MADV_NOHUGEPAGE);
|
2015-11-05 21:11:20 +03:00
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Userfault requires us to mark RAM as NOHUGEPAGE prior to discard
|
|
|
|
* however leaving it until after precopy means that most of the precopy
|
|
|
|
* data is still THPd
|
|
|
|
*/
|
|
|
|
int postcopy_ram_prepare_discard(MigrationIncomingState *mis)
|
|
|
|
{
|
|
|
|
if (qemu_ram_foreach_block(nhp_range, mis)) {
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
postcopy_state_set(POSTCOPY_INCOMING_DISCARD);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:04 +03:00
|
|
|
/*
|
|
|
|
* Mark the given area of RAM as requiring notification to unwritten areas
|
|
|
|
* Used as a callback on qemu_ram_foreach_block.
|
|
|
|
* host_addr: Base of area to mark
|
|
|
|
* offset: Offset in the whole ram arena
|
|
|
|
* length: Length of the section
|
|
|
|
* opaque: MigrationIncomingState pointer
|
|
|
|
* Returns 0 on success
|
|
|
|
*/
|
|
|
|
static int ram_block_enable_notify(const char *block_name, void *host_addr,
|
|
|
|
ram_addr_t offset, ram_addr_t length,
|
|
|
|
void *opaque)
|
|
|
|
{
|
|
|
|
MigrationIncomingState *mis = opaque;
|
|
|
|
struct uffdio_register reg_struct;
|
|
|
|
|
|
|
|
reg_struct.range.start = (uintptr_t)host_addr;
|
|
|
|
reg_struct.range.len = length;
|
|
|
|
reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
|
|
|
|
|
|
|
|
/* Now tell our userfault_fd that it's responsible for this area */
|
|
|
|
if (ioctl(mis->userfault_fd, UFFDIO_REGISTER, ®_struct)) {
|
|
|
|
error_report("%s userfault register: %s", __func__, strerror(errno));
|
|
|
|
return -1;
|
|
|
|
}
|
2017-02-24 21:28:44 +03:00
|
|
|
if (!(reg_struct.ioctls & ((__u64)1 << _UFFDIO_COPY))) {
|
|
|
|
error_report("%s userfault: Region doesn't support COPY", __func__);
|
|
|
|
return -1;
|
|
|
|
}
|
2015-11-05 21:11:04 +03:00
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Handle faults detected by the USERFAULT markings
|
|
|
|
*/
|
|
|
|
static void *postcopy_ram_fault_thread(void *opaque)
|
|
|
|
{
|
|
|
|
MigrationIncomingState *mis = opaque;
|
2015-11-05 21:11:17 +03:00
|
|
|
struct uffd_msg msg;
|
|
|
|
int ret;
|
|
|
|
RAMBlock *rb = NULL;
|
|
|
|
RAMBlock *last_rb = NULL; /* last RAMBlock we sent part of */
|
2015-11-05 21:11:04 +03:00
|
|
|
|
2015-11-05 21:11:17 +03:00
|
|
|
trace_postcopy_ram_fault_thread_entry();
|
2015-11-05 21:11:04 +03:00
|
|
|
qemu_sem_post(&mis->fault_thread_sem);
|
|
|
|
|
2015-11-05 21:11:17 +03:00
|
|
|
while (true) {
|
|
|
|
ram_addr_t rb_offset;
|
|
|
|
struct pollfd pfd[2];
|
|
|
|
|
|
|
|
/*
|
|
|
|
* We're mainly waiting for the kernel to give us a faulting HVA,
|
|
|
|
* however we can be told to quit via userfault_quit_fd which is
|
|
|
|
* an eventfd
|
|
|
|
*/
|
|
|
|
pfd[0].fd = mis->userfault_fd;
|
|
|
|
pfd[0].events = POLLIN;
|
|
|
|
pfd[0].revents = 0;
|
2018-02-08 13:31:06 +03:00
|
|
|
pfd[1].fd = mis->userfault_event_fd;
|
2015-11-05 21:11:17 +03:00
|
|
|
pfd[1].events = POLLIN; /* Waiting for eventfd to go positive */
|
|
|
|
pfd[1].revents = 0;
|
|
|
|
|
|
|
|
if (poll(pfd, 2, -1 /* Wait forever */) == -1) {
|
|
|
|
error_report("%s: userfault poll: %s", __func__, strerror(errno));
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (pfd[1].revents) {
|
2018-02-08 13:31:06 +03:00
|
|
|
uint64_t tmp64 = 0;
|
|
|
|
|
|
|
|
/* Consume the signal */
|
|
|
|
if (read(mis->userfault_event_fd, &tmp64, 8) != 8) {
|
|
|
|
/* Nothing obviously nicer than posting this error. */
|
|
|
|
error_report("%s: read() failed", __func__);
|
|
|
|
}
|
|
|
|
|
|
|
|
if (atomic_read(&mis->fault_thread_quit)) {
|
|
|
|
trace_postcopy_ram_fault_thread_quit();
|
|
|
|
break;
|
|
|
|
}
|
2015-11-05 21:11:17 +03:00
|
|
|
}
|
|
|
|
|
|
|
|
ret = read(mis->userfault_fd, &msg, sizeof(msg));
|
|
|
|
if (ret != sizeof(msg)) {
|
|
|
|
if (errno == EAGAIN) {
|
|
|
|
/*
|
|
|
|
* if a wake up happens on the other thread just after
|
|
|
|
* the poll, there is nothing to read.
|
|
|
|
*/
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
if (ret < 0) {
|
|
|
|
error_report("%s: Failed to read full userfault message: %s",
|
|
|
|
__func__, strerror(errno));
|
|
|
|
break;
|
|
|
|
} else {
|
|
|
|
error_report("%s: Read %d bytes from userfaultfd expected %zd",
|
|
|
|
__func__, ret, sizeof(msg));
|
|
|
|
break; /* Lost alignment, don't know what we'd read next */
|
|
|
|
}
|
|
|
|
}
|
|
|
|
if (msg.event != UFFD_EVENT_PAGEFAULT) {
|
|
|
|
error_report("%s: Read unexpected event %ud from userfaultfd",
|
|
|
|
__func__, msg.event);
|
|
|
|
continue; /* It's not a page fault, shouldn't happen */
|
|
|
|
}
|
|
|
|
|
|
|
|
rb = qemu_ram_block_from_host(
|
|
|
|
(void *)(uintptr_t)msg.arg.pagefault.address,
|
2016-05-26 11:07:50 +03:00
|
|
|
true, &rb_offset);
|
2015-11-05 21:11:17 +03:00
|
|
|
if (!rb) {
|
|
|
|
error_report("postcopy_ram_fault_thread: Fault outside guest: %"
|
|
|
|
PRIx64, (uint64_t)msg.arg.pagefault.address);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
2017-02-24 21:28:38 +03:00
|
|
|
rb_offset &= ~(qemu_ram_pagesize(rb) - 1);
|
2015-11-05 21:11:17 +03:00
|
|
|
trace_postcopy_ram_fault_thread_request(msg.arg.pagefault.address,
|
|
|
|
qemu_ram_get_idstr(rb),
|
2018-01-22 16:20:14 +03:00
|
|
|
rb_offset);
|
2015-11-05 21:11:17 +03:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Send the request to the source - we want to request one
|
|
|
|
* of our host page sizes (which is >= TPS)
|
|
|
|
*/
|
|
|
|
if (rb != last_rb) {
|
|
|
|
last_rb = rb;
|
|
|
|
migrate_send_rp_req_pages(mis, qemu_ram_get_idstr(rb),
|
2017-02-24 21:28:38 +03:00
|
|
|
rb_offset, qemu_ram_pagesize(rb));
|
2015-11-05 21:11:17 +03:00
|
|
|
} else {
|
|
|
|
/* Save some space */
|
|
|
|
migrate_send_rp_req_pages(mis, NULL,
|
2017-02-24 21:28:38 +03:00
|
|
|
rb_offset, qemu_ram_pagesize(rb));
|
2015-11-05 21:11:17 +03:00
|
|
|
}
|
|
|
|
}
|
|
|
|
trace_postcopy_ram_fault_thread_exit();
|
2015-11-05 21:11:04 +03:00
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
int postcopy_ram_enable_notify(MigrationIncomingState *mis)
|
|
|
|
{
|
2015-11-05 21:11:17 +03:00
|
|
|
/* Open the fd for the kernel to give us userfaults */
|
|
|
|
mis->userfault_fd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
|
|
|
|
if (mis->userfault_fd == -1) {
|
|
|
|
error_report("%s: Failed to open userfault fd: %s", __func__,
|
|
|
|
strerror(errno));
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Although the host check already tested the API, we need to
|
|
|
|
* do the check again as an ABI handshake on the new fd.
|
|
|
|
*/
|
2017-09-19 19:47:58 +03:00
|
|
|
if (!ufd_check_and_apply(mis->userfault_fd, mis)) {
|
2015-11-05 21:11:17 +03:00
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Now an eventfd we use to tell the fault-thread to quit */
|
2018-02-08 13:31:06 +03:00
|
|
|
mis->userfault_event_fd = eventfd(0, EFD_CLOEXEC);
|
|
|
|
if (mis->userfault_event_fd == -1) {
|
|
|
|
error_report("%s: Opening userfault_event_fd: %s", __func__,
|
2015-11-05 21:11:17 +03:00
|
|
|
strerror(errno));
|
|
|
|
close(mis->userfault_fd);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:04 +03:00
|
|
|
qemu_sem_init(&mis->fault_thread_sem, 0);
|
|
|
|
qemu_thread_create(&mis->fault_thread, "postcopy/fault",
|
|
|
|
postcopy_ram_fault_thread, mis, QEMU_THREAD_JOINABLE);
|
|
|
|
qemu_sem_wait(&mis->fault_thread_sem);
|
|
|
|
qemu_sem_destroy(&mis->fault_thread_sem);
|
2015-11-05 21:11:17 +03:00
|
|
|
mis->have_fault_thread = true;
|
2015-11-05 21:11:04 +03:00
|
|
|
|
|
|
|
/* Mark so that we get notified of accesses to unwritten areas */
|
|
|
|
if (qemu_ram_foreach_block(ram_block_enable_notify, mis)) {
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:23 +03:00
|
|
|
/*
|
|
|
|
* Ballooning can mark pages as absent while we're postcopying
|
|
|
|
* that would cause false userfaults.
|
|
|
|
*/
|
|
|
|
qemu_balloon_inhibit(true);
|
|
|
|
|
2015-11-05 21:11:17 +03:00
|
|
|
trace_postcopy_ram_enable_notify();
|
|
|
|
|
2015-11-05 21:11:04 +03:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2017-10-05 14:13:19 +03:00
|
|
|
static int qemu_ufd_copy_ioctl(int userfault_fd, void *host_addr,
|
2017-10-05 14:13:20 +03:00
|
|
|
void *from_addr, uint64_t pagesize, RAMBlock *rb)
|
2017-10-05 14:13:19 +03:00
|
|
|
{
|
2017-10-05 14:13:20 +03:00
|
|
|
int ret;
|
2017-10-05 14:13:19 +03:00
|
|
|
if (from_addr) {
|
|
|
|
struct uffdio_copy copy_struct;
|
|
|
|
copy_struct.dst = (uint64_t)(uintptr_t)host_addr;
|
|
|
|
copy_struct.src = (uint64_t)(uintptr_t)from_addr;
|
|
|
|
copy_struct.len = pagesize;
|
|
|
|
copy_struct.mode = 0;
|
2017-10-05 14:13:20 +03:00
|
|
|
ret = ioctl(userfault_fd, UFFDIO_COPY, ©_struct);
|
2017-10-05 14:13:19 +03:00
|
|
|
} else {
|
|
|
|
struct uffdio_zeropage zero_struct;
|
|
|
|
zero_struct.range.start = (uint64_t)(uintptr_t)host_addr;
|
|
|
|
zero_struct.range.len = pagesize;
|
|
|
|
zero_struct.mode = 0;
|
2017-10-05 14:13:20 +03:00
|
|
|
ret = ioctl(userfault_fd, UFFDIO_ZEROPAGE, &zero_struct);
|
|
|
|
}
|
|
|
|
if (!ret) {
|
|
|
|
ramblock_recv_bitmap_set_range(rb, host_addr,
|
|
|
|
pagesize / qemu_target_page_size());
|
2017-10-05 14:13:19 +03:00
|
|
|
}
|
2017-10-05 14:13:20 +03:00
|
|
|
return ret;
|
2017-10-05 14:13:19 +03:00
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:10 +03:00
|
|
|
/*
|
|
|
|
* Place a host page (from) at (host) atomically
|
|
|
|
* returns 0 on success
|
|
|
|
*/
|
2017-02-24 21:28:35 +03:00
|
|
|
int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
|
2017-10-05 14:13:18 +03:00
|
|
|
RAMBlock *rb)
|
2015-11-05 21:11:10 +03:00
|
|
|
{
|
2017-10-05 14:13:18 +03:00
|
|
|
size_t pagesize = qemu_ram_pagesize(rb);
|
2015-11-05 21:11:10 +03:00
|
|
|
|
|
|
|
/* copy also acks to the kernel waking the stalled thread up
|
|
|
|
* TODO: We can inhibit that ack and only do it if it was requested
|
|
|
|
* which would be slightly cheaper, but we'd have to be careful
|
|
|
|
* of the order of updating our page state.
|
|
|
|
*/
|
2017-10-05 14:13:20 +03:00
|
|
|
if (qemu_ufd_copy_ioctl(mis->userfault_fd, host, from, pagesize, rb)) {
|
2015-11-05 21:11:10 +03:00
|
|
|
int e = errno;
|
2017-02-24 21:28:35 +03:00
|
|
|
error_report("%s: %s copy host: %p from: %p (size: %zd)",
|
|
|
|
__func__, strerror(e), host, from, pagesize);
|
2015-11-05 21:11:10 +03:00
|
|
|
|
|
|
|
return -e;
|
|
|
|
}
|
|
|
|
|
|
|
|
trace_postcopy_place_page(host);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Place a zero page at (host) atomically
|
|
|
|
* returns 0 on success
|
|
|
|
*/
|
2017-02-24 21:28:35 +03:00
|
|
|
int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
|
2017-10-05 14:13:18 +03:00
|
|
|
RAMBlock *rb)
|
2015-11-05 21:11:10 +03:00
|
|
|
{
|
2017-02-24 21:28:35 +03:00
|
|
|
trace_postcopy_place_page_zero(host);
|
2015-11-05 21:11:10 +03:00
|
|
|
|
2017-10-05 14:13:18 +03:00
|
|
|
if (qemu_ram_pagesize(rb) == getpagesize()) {
|
2017-10-05 14:13:20 +03:00
|
|
|
if (qemu_ufd_copy_ioctl(mis->userfault_fd, host, NULL, getpagesize(),
|
|
|
|
rb)) {
|
2017-02-24 21:28:35 +03:00
|
|
|
int e = errno;
|
|
|
|
error_report("%s: %s zero host: %p",
|
|
|
|
__func__, strerror(e), host);
|
2015-11-05 21:11:10 +03:00
|
|
|
|
2017-02-24 21:28:35 +03:00
|
|
|
return -e;
|
|
|
|
}
|
|
|
|
} else {
|
2017-02-24 21:28:36 +03:00
|
|
|
/* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
|
|
|
|
if (!mis->postcopy_tmp_zero_page) {
|
|
|
|
mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
|
|
|
|
PROT_READ | PROT_WRITE,
|
|
|
|
MAP_PRIVATE | MAP_ANONYMOUS,
|
|
|
|
-1, 0);
|
|
|
|
if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
|
|
|
|
int e = errno;
|
|
|
|
mis->postcopy_tmp_zero_page = NULL;
|
|
|
|
error_report("%s: %s mapping large zero page",
|
|
|
|
__func__, strerror(e));
|
|
|
|
return -e;
|
|
|
|
}
|
|
|
|
memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
|
|
|
|
}
|
|
|
|
return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
|
2017-10-05 14:13:18 +03:00
|
|
|
rb);
|
2015-11-05 21:11:10 +03:00
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Returns a target page of memory that can be mapped at a later point in time
|
|
|
|
* using postcopy_place_page
|
|
|
|
* The same address is used repeatedly, postcopy_place_page just takes the
|
|
|
|
* backing page away.
|
|
|
|
* Returns: Pointer to allocated page
|
|
|
|
*
|
|
|
|
*/
|
|
|
|
void *postcopy_get_tmp_page(MigrationIncomingState *mis)
|
|
|
|
{
|
|
|
|
if (!mis->postcopy_tmp_page) {
|
2017-02-24 21:28:35 +03:00
|
|
|
mis->postcopy_tmp_page = mmap(NULL, mis->largest_page_size,
|
2015-11-05 21:11:10 +03:00
|
|
|
PROT_READ | PROT_WRITE, MAP_PRIVATE |
|
|
|
|
MAP_ANONYMOUS, -1, 0);
|
2016-07-29 12:48:25 +03:00
|
|
|
if (mis->postcopy_tmp_page == MAP_FAILED) {
|
|
|
|
mis->postcopy_tmp_page = NULL;
|
2015-11-05 21:11:10 +03:00
|
|
|
error_report("%s: %s", __func__, strerror(errno));
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return mis->postcopy_tmp_page;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:10:55 +03:00
|
|
|
#else
|
|
|
|
/* No target OS support, stubs just fail */
|
2017-09-19 19:47:56 +03:00
|
|
|
bool postcopy_ram_supported_by_host(MigrationIncomingState *mis)
|
2015-11-05 21:10:55 +03:00
|
|
|
{
|
|
|
|
error_report("%s: No OS support", __func__);
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:03 +03:00
|
|
|
int postcopy_ram_incoming_init(MigrationIncomingState *mis, size_t ram_pages)
|
|
|
|
{
|
|
|
|
error_report("postcopy_ram_incoming_init: No OS support");
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
|
|
|
|
{
|
|
|
|
assert(0);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:20 +03:00
|
|
|
int postcopy_ram_prepare_discard(MigrationIncomingState *mis)
|
|
|
|
{
|
|
|
|
assert(0);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:04 +03:00
|
|
|
int postcopy_ram_enable_notify(MigrationIncomingState *mis)
|
|
|
|
{
|
|
|
|
assert(0);
|
|
|
|
return -1;
|
|
|
|
}
|
2015-11-05 21:11:10 +03:00
|
|
|
|
2017-02-24 21:28:35 +03:00
|
|
|
int postcopy_place_page(MigrationIncomingState *mis, void *host, void *from,
|
2017-10-05 14:13:18 +03:00
|
|
|
RAMBlock *rb)
|
2015-11-05 21:11:10 +03:00
|
|
|
{
|
|
|
|
assert(0);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
2017-02-24 21:28:35 +03:00
|
|
|
int postcopy_place_page_zero(MigrationIncomingState *mis, void *host,
|
2017-10-05 14:13:18 +03:00
|
|
|
RAMBlock *rb)
|
2015-11-05 21:11:10 +03:00
|
|
|
{
|
|
|
|
assert(0);
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
void *postcopy_get_tmp_page(MigrationIncomingState *mis)
|
|
|
|
{
|
|
|
|
assert(0);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:10:55 +03:00
|
|
|
#endif
|
|
|
|
|
2015-11-05 21:11:02 +03:00
|
|
|
/* ------------------------------------------------------------------------- */
|
|
|
|
|
2018-02-08 13:31:07 +03:00
|
|
|
void postcopy_fault_thread_notify(MigrationIncomingState *mis)
|
|
|
|
{
|
|
|
|
uint64_t tmp64 = 1;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Wakeup the fault_thread. It's an eventfd that should currently
|
|
|
|
* be at 0, we're going to increment it to 1
|
|
|
|
*/
|
|
|
|
if (write(mis->userfault_event_fd, &tmp64, 8) != 8) {
|
|
|
|
/* Not much we can do here, but may as well report it */
|
|
|
|
error_report("%s: incrementing failed: %s", __func__,
|
|
|
|
strerror(errno));
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2015-11-05 21:11:02 +03:00
|
|
|
/**
|
|
|
|
* postcopy_discard_send_init: Called at the start of each RAMBlock before
|
|
|
|
* asking to discard individual ranges.
|
|
|
|
*
|
|
|
|
* @ms: The current migration state.
|
|
|
|
* @offset: the bitmap offset of the named RAMBlock in the migration
|
|
|
|
* bitmap.
|
|
|
|
* @name: RAMBlock that discards will operate on.
|
|
|
|
*
|
|
|
|
* returns: a new PDS.
|
|
|
|
*/
|
|
|
|
PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
|
|
|
|
const char *name)
|
|
|
|
{
|
|
|
|
PostcopyDiscardState *res = g_malloc0(sizeof(PostcopyDiscardState));
|
|
|
|
|
|
|
|
if (res) {
|
|
|
|
res->ramblock_name = name;
|
|
|
|
}
|
|
|
|
|
|
|
|
return res;
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* postcopy_discard_send_range: Called by the bitmap code for each chunk to
|
|
|
|
* discard. May send a discard message, may just leave it queued to
|
|
|
|
* be sent later.
|
|
|
|
*
|
|
|
|
* @ms: Current migration state.
|
|
|
|
* @pds: Structure initialised by postcopy_discard_send_init().
|
|
|
|
* @start,@length: a range of pages in the migration bitmap in the
|
|
|
|
* RAM block passed to postcopy_discard_send_init() (length=1 is one page)
|
|
|
|
*/
|
|
|
|
void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds,
|
|
|
|
unsigned long start, unsigned long length)
|
|
|
|
{
|
2017-03-21 11:09:14 +03:00
|
|
|
size_t tp_size = qemu_target_page_size();
|
2015-11-05 21:11:02 +03:00
|
|
|
/* Convert to byte offsets within the RAM block */
|
2017-03-22 17:18:04 +03:00
|
|
|
pds->start_list[pds->cur_entry] = start * tp_size;
|
2017-03-21 11:09:14 +03:00
|
|
|
pds->length_list[pds->cur_entry] = length * tp_size;
|
2015-11-05 21:11:02 +03:00
|
|
|
trace_postcopy_discard_send_range(pds->ramblock_name, start, length);
|
|
|
|
pds->cur_entry++;
|
|
|
|
pds->nsentwords++;
|
|
|
|
|
|
|
|
if (pds->cur_entry == MAX_DISCARDS_PER_COMMAND) {
|
|
|
|
/* Full set, ship it! */
|
2016-01-15 06:37:42 +03:00
|
|
|
qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
|
|
|
|
pds->ramblock_name,
|
2015-11-05 21:11:02 +03:00
|
|
|
pds->cur_entry,
|
|
|
|
pds->start_list,
|
|
|
|
pds->length_list);
|
|
|
|
pds->nsentcmds++;
|
|
|
|
pds->cur_entry = 0;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* postcopy_discard_send_finish: Called at the end of each RAMBlock by the
|
|
|
|
* bitmap code. Sends any outstanding discard messages, frees the PDS
|
|
|
|
*
|
|
|
|
* @ms: Current migration state.
|
|
|
|
* @pds: Structure initialised by postcopy_discard_send_init().
|
|
|
|
*/
|
|
|
|
void postcopy_discard_send_finish(MigrationState *ms, PostcopyDiscardState *pds)
|
|
|
|
{
|
|
|
|
/* Anything unsent? */
|
|
|
|
if (pds->cur_entry) {
|
2016-01-15 06:37:42 +03:00
|
|
|
qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
|
|
|
|
pds->ramblock_name,
|
2015-11-05 21:11:02 +03:00
|
|
|
pds->cur_entry,
|
|
|
|
pds->start_list,
|
|
|
|
pds->length_list);
|
|
|
|
pds->nsentcmds++;
|
|
|
|
}
|
|
|
|
|
|
|
|
trace_postcopy_discard_send_finish(pds->ramblock_name, pds->nsentwords,
|
|
|
|
pds->nsentcmds);
|
|
|
|
|
|
|
|
g_free(pds);
|
|
|
|
}
|
2017-04-24 17:50:35 +03:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Current state of incoming postcopy; note this is not part of
|
|
|
|
* MigrationIncomingState since it's state is used during cleanup
|
|
|
|
* at the end as MIS is being freed.
|
|
|
|
*/
|
|
|
|
static PostcopyState incoming_postcopy_state;
|
|
|
|
|
|
|
|
PostcopyState postcopy_state_get(void)
|
|
|
|
{
|
|
|
|
return atomic_mb_read(&incoming_postcopy_state);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Set the state and return the old state */
|
|
|
|
PostcopyState postcopy_state_set(PostcopyState new_state)
|
|
|
|
{
|
|
|
|
return atomic_xchg(&incoming_postcopy_state, new_state);
|
|
|
|
}
|