4:47 a.m.
This patch adds save/restore functionality to the libxl driver.
It is a v2 of this patch:
https://www.redhat.com/archives/libvir-list/2011-April/msg00338.html
v2:
* header is now padded and has a version field
* the correct restore function from libxl is used
* only create the restore event once in libxlVmStart
However I ran into a reproducible segfault.
Assume you saved a vm with:
# virsh save domU foo.img
If you restore the save image,
destroy the vm and restore it again, a segfault occurs:
# virsh restore foo.img
# virsh destroy domU
# virsh restore foo.img
# segfault
If you restart libvirt between the restores no segfault occurs:
# virsh restore foo.img
# virsh destroy domU
# restart libvirt
# virsh restore foo.img
According to a gdb backtrace a memcpy from the function xc_domain_restore
is causing the segfault.
Then I saved a vm with the xl tool (which also uses the libxenlight interface)
and restored it twice. No segfault occured.
So I figured something must went wrong in libvirt.
However I was unable to identify the responsible part of code.
Now I am hoping that a review will possibly solve this issue.
Here is the gdb backtrace:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x42ba1950 (LWP 23813)]
0x00007f1bc17d906b in memcpy () from /lib/libc.so.6
(gdb) bt
#0 0x00007f1bc17d906b in memcpy () from /lib/libc.so.6
#1 0x00007f1bc2b49346 in xc_domain_restore () from /usr/lib/libxenguest.so.4.0
#2 0x00007f1bc31a80f3 in ?? () from /usr/lib/libxenlight.so.1.0
#3 0x00007f1bc31a105e in ?? () from /usr/lib/libxenlight.so.1.0
#4 0x000000000049389a in libxlVmStart (driver=0x7f1bb8003e80, vm=0x7f1bb8053400,
start_paused=false, restore_fd=20) at libxl/libxl_driver.c:531
#5 0x00000000004945c5 in libxlDomainRestore (conn=<value optimized out>,
from=<value optimized out>) at libxl/libxl_driver.c:1745
#6 0x00007f1bc1f85a4b in virDomainRestore (conn=0x20a4d40, from=0x7f1bb804d260
"/root/tt.img") at libvirt.c:2330
#7 0x000000000042c5b8 in remoteDispatchDomainRestore (server=<value optimized out>,
client=<value optimized out>, conn=0xaf0, hdr=<value optimized out>,
rerr=0x42ba0e20,
args=0xffffffff, ret=0x42ba0f00) at remote.c:2616
#8 0x0000000000431cb7 in remoteDispatchClientRequest (server=0x209fe90, client=0x20a4ad0,
msg=0x20b1aa0) at dispatch.c:524
#9 0x000000000041dd53 in qemudWorker (data=0x20a8018) at libvirtd.c:1622
#10 0x00007f1bc1cb9fc7 in start_thread () from /lib/libpthread.so.0
#11 0x00007f1bc182b64d in clone () from /lib/libc.so.6
#12 0x0000000000000000 in ?? ()
Cheers,
Markus
---
src/libxl/libxl_conf.h | 14 +++
src/libxl/libxl_driver.c | 228 ++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 225 insertions(+), 17 deletions(-)
diff --git a/src/libxl/libxl_conf.h b/src/libxl/libxl_conf.h
index 8c87786..e7dd3a1 100644
--- a/src/libxl/libxl_conf.h
+++ b/src/libxl/libxl_conf.h
@@ -1,5 +1,6 @@
/*---------------------------------------------------------------------------*/
/* Copyright (c) 2011 SUSE LINUX Products GmbH, Nuernberg, Germany.
+ * Copyright (C) 2011 Univention GmbH.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@@ -17,6 +18,7 @@
*
* Authors:
* Jim Fehlig <jfehlig(a)novell.com>
+ * Markus Groß <gross(a)univention.de>
*/
/*---------------------------------------------------------------------------*/
@@ -85,6 +87,18 @@ struct _libxlDomainObjPrivate {
int eventHdl;
};
+#define LIBXL_SAVE_MAGIC "libvirt-xml\n \0 \r"
+#define LIBXL_SAVE_VERSION 1
+
+typedef struct _libxlSavefileHeader libxlSavefileHeader;
+typedef libxlSavefileHeader *libxlSavefileHeaderPtr;
+struct _libxlSavefileHeader {
+ char magic[sizeof(LIBXL_SAVE_MAGIC)-1];
+ uint32_t version;
+ uint32_t xmlLen;
+ /* 24 bytes used, pad up to 64 bytes */
+ uint32_t unused[10];
+};
# define libxlError(code, ...) \
virReportErrorHelper(VIR_FROM_LIBXL, code, __FILE__, \
diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index 247d78e..56a62c9 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -29,6 +29,7 @@
#include <sys/utsname.h>
#include <math.h>
#include <libxl.h>
+#include <fcntl.h>
#include "internal.h"
#include "logging.h"
@@ -60,11 +61,10 @@
static libxlDriverPrivatePtr libxl_driver = NULL;
-
/* Function declarations */
static int
-libxlVmStart(libxlDriverPrivatePtr driver,
- virDomainObjPtr vm, bool start_paused);
+libxlVmStart(libxlDriverPrivatePtr driver, virDomainObjPtr vm,
+ bool start_paused, int restore_fd);
/* Function definitions */
@@ -188,7 +188,7 @@ libxlAutostartDomain(void *payload, const void *name
ATTRIBUTE_UNUSED,
virResetLastError();
if (vm->autostart && !virDomainObjIsActive(vm) &&
- libxlVmStart(driver, vm, false) < 0) {
+ libxlVmStart(driver, vm, false, -1) < 0) {
err = virGetLastError();
VIR_ERROR(_("Failed to autostart VM '%s': %s"),
vm->def->name,
@@ -378,7 +378,7 @@ static void libxlEventHandler(int watch,
break;
case SHUTDOWN_reboot:
libxlVmReap(driver, vm, 0);
- libxlVmStart(driver, vm, 0);
+ libxlVmStart(driver, vm, 0, -1);
break;
default:
VIR_INFO("Unhandled shutdown_reason %d",
info.shutdown_reason);
@@ -504,8 +504,8 @@ cleanup:
* virDomainObjPtr should be locked on invocation
*/
static int
-libxlVmStart(libxlDriverPrivatePtr driver,
- virDomainObjPtr vm, bool start_paused)
+libxlVmStart(libxlDriverPrivatePtr driver, virDomainObjPtr vm,
+ bool start_paused, int restore_fd)
{
libxl_domain_config d_config;
virDomainDefPtr def = vm->def;
@@ -524,12 +524,23 @@ libxlVmStart(libxlDriverPrivatePtr driver,
//TODO: Balloon dom0 ??
//ret = freemem(&d_config->b_info, &d_config->dm_info);
- ret = libxl_domain_create_new(&priv->ctx, &d_config,
- NULL, &child_console_pid, &domid);
+ if (restore_fd < 0)
+ ret = libxl_domain_create_new(&priv->ctx, &d_config,
+ NULL, &child_console_pid, &domid);
+ else
+ ret = libxl_domain_create_restore(&priv->ctx, &d_config, NULL,
+ &child_console_pid, &domid,
+ restore_fd);
+
if (ret) {
- libxlError(VIR_ERR_INTERNAL_ERROR,
- _("libxenlight failed to create new domain '%s'"),
- d_config.c_info.name);
+ if (restore_fd < 0)
+ libxlError(VIR_ERR_INTERNAL_ERROR,
+ _("libxenlight failed to create new domain
'%s'"),
+ d_config.c_info.name);
+ else
+ libxlError(VIR_ERR_INTERNAL_ERROR,
+ _("libxenlight failed to restore domain '%s'"),
+ d_config.c_info.name);
goto error;
}
@@ -562,7 +573,9 @@ libxlVmStart(libxlDriverPrivatePtr driver,
goto error;
event = virDomainEventNewFromObj(vm, VIR_DOMAIN_EVENT_STARTED,
- VIR_DOMAIN_EVENT_STARTED_BOOTED);
+ restore_fd < 0 ?
+ VIR_DOMAIN_EVENT_STARTED_BOOTED :
+ VIR_DOMAIN_EVENT_STARTED_RESTORED);
libxlDomainEventQueue(driver, event);
libxl_domain_config_destroy(&d_config);
@@ -1046,7 +1059,8 @@ libxlDomainCreateXML(virConnectPtr conn, const char *xml,
goto cleanup;
def = NULL;
- if (libxlVmStart(driver, vm, (flags & VIR_DOMAIN_START_PAUSED) != 0) < 0) {
+ if (libxlVmStart(driver, vm, (flags & VIR_DOMAIN_START_PAUSED) != 0,
+ -1) < 0) {
virDomainRemoveInactive(&driver->domains, vm);
vm = NULL;
goto cleanup;
@@ -1566,6 +1580,186 @@ libxlDomainGetInfo(virDomainPtr dom, virDomainInfoPtr info)
}
static int
+libxlDomainSave(virDomainPtr dom, const char * to)
+{
+ libxlDriverPrivatePtr driver = dom->conn->privateData;
+ virDomainObjPtr vm;
+ libxlDomainObjPrivatePtr priv;
+ virDomainEventPtr event = NULL;
+ libxlSavefileHeader hdr;
+ libxl_domain_suspend_info s_info;
+ char *xml;
+ uint32_t xml_len;
+ int fd;
+ int ret = -1;
+
+ libxlDriverLock(driver);
+ vm = virDomainFindByUUID(&driver->domains, dom->uuid);
+
+ if (!vm) {
+ char uuidstr[VIR_UUID_STRING_BUFLEN];
+ virUUIDFormat(dom->uuid, uuidstr);
+ libxlError(VIR_ERR_NO_DOMAIN,
+ _("No domain with matching uuid '%s'"), uuidstr);
+ goto cleanup;
+ }
+
+ if (!virDomainObjIsActive(vm)) {
+ libxlError(VIR_ERR_OPERATION_INVALID, "%s", _("Domain is not
running"));
+ goto cleanup;
+ }
+
+ priv = vm->privateData;
+
+ if (vm->state != VIR_DOMAIN_PAUSED) {
+ memset(&s_info, 0, sizeof(s_info));
+
+ if ((fd = virFileOpenAs(to, O_CREAT|O_TRUNC|O_WRONLY, S_IRUSR|S_IWUSR,
+ getuid(), getgid(), 0)) < 0) {
+ virReportSystemError(-fd,
+ _("Failed to create domain save file
'%s'"),
+ to);
+ goto cleanup;
+ }
+
+ if ((xml = virDomainDefFormat(vm->def, 0)) == NULL)
+ goto cleanup;
+ xml_len = strlen(xml) + 1;
+
+ memset(&hdr, 0, sizeof(hdr));
+ memcpy(hdr.magic, LIBXL_SAVE_MAGIC, sizeof(hdr.magic));
+ hdr.version = LIBXL_SAVE_VERSION;
+ hdr.xmlLen = xml_len;
+
+ if (safewrite(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) {
+ libxlError(VIR_ERR_OPERATION_FAILED,
+ _("Failed to write save file header"));
+ goto cleanup;
+ }
+
+ if (safewrite(fd, xml, xml_len) != xml_len) {
+ libxlError(VIR_ERR_OPERATION_FAILED,
+ _("Failed to write xml description"));
+ goto cleanup;
+ }
+
+ if (libxl_domain_suspend(&priv->ctx, &s_info, dom->id, fd) != 0) {
+ libxlError(VIR_ERR_INTERNAL_ERROR,
+ _("Failed to save domain '%d' with
libxenlight"),
+ dom->id);
+ goto cleanup;
+ }
+
+ event = virDomainEventNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
+ VIR_DOMAIN_EVENT_STOPPED_SAVED);
+
+ if (libxlVmReap(driver, vm, 1) != 0) {
+ libxlError(VIR_ERR_INTERNAL_ERROR,
+ _("Failed to destroy domain '%d'"),
dom->id);
+ goto cleanup;
+ }
+
+ if (!vm->persistent) {
+ virDomainRemoveInactive(&driver->domains, vm);
+ vm = NULL;
+ }
+ ret = 0;
+ }
+cleanup:
+ VIR_FREE(xml);
+ if (VIR_CLOSE(fd) < 0)
+ virReportSystemError(errno, "%s", _("cannot close file"));
+ if (vm)
+ virDomainObjUnlock(vm);
+ if (event)
+ libxlDomainEventQueue(driver, event);
+ libxlDriverUnlock(driver);
+ return ret;
+}
+
+static int
+libxlDomainRestore(virConnectPtr conn, const char * from)
+{
+ libxlDriverPrivatePtr driver = conn->privateData;
+ virDomainDefPtr def = NULL;
+ virDomainObjPtr vm = NULL;
+ libxlSavefileHeader hdr;
+ char *xml = NULL;
+ int fd;
+ int ret = -1;
+
+ libxlDriverLock(driver);
+
+ if ((fd = virFileOpenAs(from, O_RDONLY, 0, getuid(), getgid(), 0)) < 0) {
+ libxlError(VIR_ERR_OPERATION_FAILED,
+ "%s", _("cannot read domain image"));
+ goto cleanup;
+ }
+
+ if (saferead(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) {
+ libxlError(VIR_ERR_OPERATION_FAILED,
+ "%s", _("failed to read libxl header"));
+ goto cleanup;
+ }
+
+ if (memcmp(hdr.magic, LIBXL_SAVE_MAGIC, sizeof(hdr.magic))) {
+ libxlError(VIR_ERR_INVALID_ARG, "%s", _("image magic is
incorrect"));
+ goto cleanup;
+ }
+
+ if (hdr.version > LIBXL_SAVE_VERSION) {
+ libxlError(VIR_ERR_OPERATION_FAILED,
+ _("image version is not supported (%d > %d)"),
+ hdr.version, LIBXL_SAVE_VERSION);
+ goto cleanup;
+ }
+
+ if (hdr.xmlLen <= 0) {
+ libxlError(VIR_ERR_OPERATION_FAILED,
+ _("invalid XML length: %d"), hdr.xmlLen);
+ goto cleanup;
+ }
+
+ if (VIR_ALLOC_N(xml, hdr.xmlLen) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ if (saferead(fd, xml, hdr.xmlLen) != hdr.xmlLen) {
+ libxlError(VIR_ERR_OPERATION_FAILED, "%s", _("failed to read
XML"));
+ goto cleanup;
+ }
+
+ if (!(def = virDomainDefParseString(driver->caps, xml,
+ VIR_DOMAIN_XML_INACTIVE)))
+ goto cleanup;
+
+ if (virDomainObjIsDuplicate(&driver->domains, def, 1) < 0)
+ goto cleanup;
+
+ if (!(vm = virDomainAssignDef(driver->caps, &driver->domains, def, true)))
+ goto cleanup;
+
+ def = NULL;
+
+ if ((ret = libxlVmStart(driver, vm, false, fd)) < 0 &&
+ !vm->persistent) {
+ virDomainRemoveInactive(&driver->domains, vm);
+ vm = NULL;
+ }
+
+cleanup:
+ VIR_FREE(xml);
+ virDomainDefFree(def);
+ if (VIR_CLOSE(fd) < 0)
+ virReportSystemError(errno, "%s", _("cannot close file"));
+ if (vm)
+ virDomainObjUnlock(vm);
+ libxlDriverUnlock(driver);
+ return ret;
+}
+
+static int
libxlDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
unsigned int flags)
{
@@ -2036,7 +2230,7 @@ libxlDomainCreateWithFlags(virDomainPtr dom,
goto cleanup;
}
- ret = libxlVmStart(driver, vm, (flags & VIR_DOMAIN_START_PAUSED) != 0);
+ ret = libxlVmStart(driver, vm, (flags & VIR_DOMAIN_START_PAUSED) != 0, -1);
cleanup:
if (vm)
@@ -2672,8 +2866,8 @@ static virDriver libxlDriver = {
NULL, /* domainSetBlkioParameters */
NULL, /* domainGetBlkioParameters */
libxlDomainGetInfo, /* domainGetInfo */
- NULL, /* domainSave */
- NULL, /* domainRestore */
+ libxlDomainSave, /* domainSave */
+ libxlDomainRestore, /* domainRestore */
NULL, /* domainCoreDump */
libxlDomainSetVcpus, /* domainSetVcpus */
libxlDomainSetVcpusFlags, /* domainSetVcpusFlags */
--
1.7.1