Markus Groà wrote: > 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 > Hi Markus, Finally found time to try your patch. Thanks for the patience :-). > > However I ran into a reproducible segfault. > Assume you saved a vm with: > # virsh save domU foo.img > I think the problem actually lies in the save function. The domain does not appear to be cleaned up properly. From xl's perspective after virsh save domU foo.img xen33: # xl list Name ID Mem VCPUs State Time(s) Domain-0 0 2023 8 r----- 330.0 (null) 11 1 2 --pssd 27.1 The orphaned domain disappears after libvirtd restart. I tinkered with the cleanup code path with no success, but wanted to let you know my findings before knocking off for the night. I'll continue poking around tomorrow. Cheers, Jim > 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@xxxxxxxxxx> > + * Markus Groà <gross@xxxxxxxxxxxxx> > */ > /*---------------------------------------------------------------------------*/ > > @@ -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 > > -- > libvir-list mailing list > libvir-list@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/libvir-list -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list