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[Qemu-devel] [PATCH v6 25/47] postcopy: OS support test
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PATCH v6 25/47] postcopy: OS support test |
Date: |
Tue, 14 Apr 2015 18:03:51 +0100 |
From: "Dr. David Alan Gilbert" <address@hidden>
Provide a check to see if the OS we're running on has all the bits
needed for postcopy.
Creates postcopy-ram.c which will get most of the other helpers we need.
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
include/migration/postcopy-ram.h | 19 +++++
migration/Makefile.objs | 2 +-
migration/postcopy-ram.c | 157 +++++++++++++++++++++++++++++++++++++++
savevm.c | 5 ++
4 files changed, 182 insertions(+), 1 deletion(-)
create mode 100644 include/migration/postcopy-ram.h
create mode 100644 migration/postcopy-ram.c
diff --git a/include/migration/postcopy-ram.h b/include/migration/postcopy-ram.h
new file mode 100644
index 0000000..d81934f
--- /dev/null
+++ b/include/migration/postcopy-ram.h
@@ -0,0 +1,19 @@
+/*
+ * Postcopy migration for RAM
+ *
+ * Copyright 2013 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Dave Gilbert <address@hidden>
+ *
+ * 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 QEMU_POSTCOPY_RAM_H
+#define QEMU_POSTCOPY_RAM_H
+
+/* Return true if the host supports everything we need to do postcopy-ram */
+bool postcopy_ram_supported_by_host(void);
+
+#endif
diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index d929e96..0cac6d7 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -1,7 +1,7 @@
common-obj-y += migration.o tcp.o
common-obj-y += vmstate.o
common-obj-y += qemu-file.o qemu-file-buf.o qemu-file-unix.o qemu-file-stdio.o
-common-obj-y += xbzrle.o
+common-obj-y += xbzrle.o postcopy-ram.o
common-obj-$(CONFIG_RDMA) += rdma.o
common-obj-$(CONFIG_POSIX) += exec.o unix.o fd.o
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
new file mode 100644
index 0000000..7704bc1
--- /dev/null
+++ b/migration/postcopy-ram.c
@@ -0,0 +1,157 @@
+/*
+ * Postcopy migration for RAM
+ *
+ * Copyright 2013-2015 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Dave Gilbert <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+/*
+ * Postcopy is a migration technique where the execution flips from the
+ * source to the destination before all the data has been copied.
+ */
+
+#include <glib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "qemu-common.h"
+#include "migration/migration.h"
+#include "migration/postcopy-ram.h"
+#include "sysemu/sysemu.h"
+#include "qemu/error-report.h"
+#include "trace.h"
+
+/* Postcopy needs to detect accesses to pages that haven't yet been copied
+ * across, and efficiently map new pages in, the techniques for doing this
+ * are target OS specific.
+ */
+#if defined(__linux__)
+
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <asm/types.h> /* for __u64 */
+#endif
+
+#if defined(__linux__) && defined(__NR_userfaultfd)
+#include <linux/userfaultfd.h>
+
+static bool ufd_version_check(int ufd)
+{
+ struct uffdio_api api_struct;
+ uint64_t feature_mask;
+
+ api_struct.api = UFFD_API;
+ if (ioctl(ufd, UFFDIO_API, &api_struct)) {
+ error_report("postcopy_ram_supported_by_host: UFFDIO_API failed: %s",
+ strerror(errno));
+ return false;
+ }
+
+ feature_mask = (__u64)1 << _UFFDIO_REGISTER |
+ (__u64)1 << _UFFDIO_UNREGISTER;
+ if ((api_struct.ioctls & feature_mask) != feature_mask) {
+ error_report("Missing userfault features: %" PRIx64,
+ (uint64_t)(~api_struct.ioctls & feature_mask));
+ return false;
+ }
+
+ return true;
+}
+
+bool postcopy_ram_supported_by_host(void)
+{
+ long pagesize = getpagesize();
+ int ufd = -1;
+ bool ret = false; /* Error unless we change it */
+ void *testarea = NULL;
+ struct uffdio_register reg_struct;
+ struct uffdio_range range_struct;
+ uint64_t feature_mask;
+
+ if ((1ul << qemu_target_page_bits()) > pagesize) {
+ error_report("Target page size bigger than host page size");
+ goto out;
+ }
+
+ ufd = syscall(__NR_userfaultfd, O_CLOEXEC);
+ if (ufd == -1) {
+ error_report("%s: userfaultfd not available: %s", __func__,
+ strerror(errno));
+ goto out;
+ }
+
+ /* Version and features check */
+ if (!ufd_version_check(ufd)) {
+ goto out;
+ }
+
+ /*
+ * We need to check that the ops we need are supported on anon memory
+ * To do that we need to register a chunk and see the flags that
+ * are returned.
+ */
+ testarea = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE |
+ MAP_ANONYMOUS, -1, 0);
+ if (testarea == MAP_FAILED) {
+ error_report("%s: Failed to map test area: %s", __func__,
+ strerror(errno));
+ goto out;
+ }
+ g_assert(((size_t)testarea & (pagesize-1)) == 0);
+
+ reg_struct.range.start = (uintptr_t)testarea;
+ reg_struct.range.len = pagesize;
+ reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
+
+ if (ioctl(ufd, UFFDIO_REGISTER, ®_struct)) {
+ error_report("%s userfault register: %s", __func__, strerror(errno));
+ goto out;
+ }
+
+ range_struct.start = (uintptr_t)testarea;
+ range_struct.len = pagesize;
+ if (ioctl(ufd, UFFDIO_UNREGISTER, &range_struct)) {
+ error_report("%s userfault unregister: %s", __func__, strerror(errno));
+ goto out;
+ }
+
+ feature_mask = (__u64)1 << _UFFDIO_WAKE |
+ (__u64)1 << _UFFDIO_COPY |
+ (__u64)1 << _UFFDIO_ZEROPAGE;
+ if ((reg_struct.ioctls & feature_mask) != feature_mask) {
+ error_report("Missing userfault map features: %" PRIx64,
+ (uint64_t)(~reg_struct.ioctls & feature_mask));
+ goto out;
+ }
+
+ /* Success! */
+ ret = true;
+out:
+ if (testarea) {
+ munmap(testarea, pagesize);
+ }
+ if (ufd != -1) {
+ close(ufd);
+ }
+ return ret;
+}
+
+#else
+/* No target OS support, stubs just fail */
+
+bool postcopy_ram_supported_by_host(void)
+{
+ error_report("%s: No OS support", __func__);
+ return false;
+}
+
+#endif
+
diff --git a/savevm.c b/savevm.c
index 79bbded..23cc99e 100644
--- a/savevm.c
+++ b/savevm.c
@@ -33,6 +33,7 @@
#include "qemu/timer.h"
#include "audio/audio.h"
#include "migration/migration.h"
+#include "migration/postcopy-ram.h"
#include "qemu/sockets.h"
#include "qemu/queue.h"
#include "sysemu/cpus.h"
@@ -1113,6 +1114,10 @@ static int
loadvm_postcopy_handle_advise(MigrationIncomingState *mis,
return -1;
}
+ if (!postcopy_ram_supported_by_host()) {
+ return -1;
+ }
+
if (remote_hps != getpagesize()) {
/*
* Some combinations of mismatch are probably possible but it gets
--
2.1.0
- [Qemu-devel] [PATCH v6 15/47] Return path: Send responses from destination to source, (continued)
- [Qemu-devel] [PATCH v6 15/47] Return path: Send responses from destination to source, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 14/47] Return path: Control commands, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 17/47] ram_debug_dump_bitmap: Dump a migration bitmap as text, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 18/47] Move loadvm_handlers into MigrationIncomingState, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 16/47] Return path: Source handling of return path, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 19/47] Rework loadvm path for subloops, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 20/47] Add migration-capability boolean for postcopy-ram., Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 22/47] MIG_CMD_PACKAGED: Send a packaged chunk of migration stream, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 23/47] migrate_init: Call from savevm, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 24/47] Modify save_live_pending for postcopy, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 25/47] postcopy: OS support test,
Dr. David Alan Gilbert (git) <=
- [Qemu-devel] [PATCH v6 26/47] migrate_start_postcopy: Command to trigger transition to postcopy, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 21/47] Add wrappers and handlers for sending/receiving the postcopy-ram migration messages., Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 27/47] MIGRATION_STATUS_POSTCOPY_ACTIVE: Add new migration state, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 28/47] Add qemu_savevm_state_complete_postcopy, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 32/47] Postcopy: Postcopy startup in migration thread, Dr. David Alan Gilbert (git), 2015/04/14
- [Qemu-devel] [PATCH v6 30/47] postcopy: Incoming initialisation, Dr. David Alan Gilbert (git), 2015/04/14